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Cranial endocasts are one of the most direct tools available to obtain information about the endocranial cavity of fossil mammals, but few anatomical comparisons have analyzed endocranial data within a phylogenetic framework. Our study combines analyses of new digital endocasts from high-resolution X-ray micro-computed tomography (µCT) for two notoungulates, Cochilius sp. and Notostylops murinus, with data from published anatomical descriptions and endocasts (prior µCT digital endocasts and natural and extracted plaster endocasts), resulting in 22 endocranial characters (11 new) scored on 20 notoungulates and five outgroups. These data permitted a comparative study of cranial endocasts of notoungulates, an enigmatic group of extinct South American mammals, shedding light on several important issues concerning their phylogenetic relationships. The new endocranial data were integrated into a craniodental and postcranial matrix, resulting in 259 characters across 65 taxa, the most comprehensive character and taxon sampling to date and the only one including a substantial suite of endocranial characters. We further performed ancestral state reconstructions for endocranial characters using parsimony optimization on the resulting phylogenetic trees. Body mass estimates and endocranial volumes were used to calculate Encephalization Quotients (EQs) and Phylogenetic Encephalization Quotients (PEQs), which then were optimized onto the phylogenies. Endocast data from ancestral character state reconstructions bear on relationships among meridiungulates, revealing that many endocast characters may be synapomorphies for Notoungulata and other clades within the group. Notoungulates, in general, display relatively low EQs when compared with Holarctic herbivorous mammals, potentially due to their long history of evolution in isolation in South America during the Cenozoic.

Tooth size variation within fossil assemblages can be associated with intra- or interspecific variation, functional, developmental, and geographical factors, and/or sexual dimorphism. Understanding these sources of variation is necessary to develop diagnoses for fossil mammals, where teeth are usually the most frequent remains. Tremacyllus (Ameghino, 1891) (Hegetotheriidae, Notoungulata) is a genus of small-sized herbivorous mammals abundant in late Miocene to Pliocene outcrops of southern South America. Its simplified, euhypsodont dentition and size variability have hampered systematics studies and led, for instance, to an overestimation of the number of species. I analyzed tooth size variations within assemblages of Tremacyllus in a quantitative framework to test three hypotheses: (1) magnitudes of size variation are different among tooth loci and assemblages; (2) tooth size follows a geographical pattern within the analyzed sample (Bergmann’s rule), but is also associated with taxonomy; and (3) there is a correlation between size variation and sexual dimorphism reflected in distinguishable subgroups. Results indicate that patterns of variation might be associated with eruption time and/or functional position. Northwestern forms are larger than southwestern-Pampean ones, not conforming to Bergmann’s rule but revealing a strong influence of latitude. Size differences between assemblages agree with dental features that distinguish T. incipiens and T. impressus, allowing expanded species diagnoses. Two size subgroups might reflect sexual dimorphism in the absence of biostratigraphic or morphological differences between them. This interpretation indicates that northwestern specimens referred to T. diminutus should be referred to T. incipiens.

Studies focused on deciduous dentition, ontogenetic series, and tooth eruption and replacement patterns in fossil mammals have lately increased due to the recognized taxonomic and phylogenetic weight of these aspects. A study of the deciduous and permanent dentition of Interatherium and Protypotherium (Interatheriinae) is presented, based mainly on unpublished materials. Deciduous cheek teeth are brachydont and placed covering the apex of the respective permanent tooth; in addition, some morphological and metrical differences are observed along the crown height. Five dental ontogenetic stages are distinguished among the juvenile specimens on the basis of the degree of wear, the replacement of the deciduous premolars, and the eruption of the molars. The crown height and the wear degree of different Interatheriinae taxa show: (1) eruption pattern of molars in an anterior–posterior direction (M/m1 to M/m3); (2) pattern of replacement of deciduous premolars and eruption of permanent premolars in a posterior–anterior direction (dP/dp4 to dP/dp2 and P/p4 to P/p2); and (3) eruption of M/m3 before the replacement of dP/dp4. Results allow evaluating the diagnostic dental characteristics used to describe some interatheriines, as well as reinterpreting some taxonomic assumptions: the holotype of Protypotherium diversidens Ameghino, 1891 is recognized as a juvenile of another species of the genus, and the species is not validated, considering it as Protypotherium sp.; the holotype of Eudiastatus lingulatus Ameghino, 1891 falls in the variability of Protypotherium, becoming P. lingulatus new combination, tentatively maintaining the species and implying the synonymy between Eudiastatus and Protypotherium; and the holotype of Eopachyrucos ranchoverdensis Reguero, Ubilla, and Perea, 2003 is reinterpreted as bearing deciduous premolars.

A remarkable diversity of plant-eating mammals known as South American native ungulates (SANUs) flourished in South America for most of the Cenozoic. Although some of these species likely filled ecological niches similar to those of modern hoofed mammals, others differed substantially from extant artiodactyls and perissodactyls in their skull and limb anatomy and probably also in their ecology. Notoungulates and litopterns were the longest-lived and most diverse SANU clades and survived into the Quaternary; astrapotheres went extinct in the late Miocene, whereas other SANU groups were restricted to the Paleogene. Neogene notoungulates were quite specialized in craniodental structure, but many were rather unspecialized postcranially; in contrast, litopterns evolved limb specializations early in their history while maintaining more conservative dentitions. In this article, we review the current understanding of SANU evolutionary relationships and paleoecology, provide an updated compilation of genus temporal ranges, and discuss possible directions for future research. ▪ South American native ungulates (SANUs) were a diverse, long-lived, and independent radiation of mammals into varied terrestrial plant-eater niches. ▪ We review origins, evolution, and paleoecology of the major SANU clades: Notoungulata, Litopterna, Astrapotheria, Xenungulata, and Pyrotheria. ▪ At their peak, during the Eocene and Oligocene, more than 40 genera of native ungulates inhabited South America at any one time. ▪ SANUs ranged from

Interatheriinae is one of the most derived subfamilies of South American notoungulates. Several interatheriines have been described since the 19th century, but most of them have not been revised, o...

The arrangement of the tarsus has been used to differentiate afrotherian and laurasiatherian ungulates for more than a century, and it is often present in morphological matrices that include appendicular features. Traditionally, it has two states: (i) an alternating tarsus, where proximal elements are interlocked with central and distal elements positioned like the bricks of a wall; and (ii) a serial tarsus, where elements are not interlocked. Over the years, these states became synonymous with the presence or absence of an astragalocuboid contact. Within the South American order Notoungulata, a third disposition was recognized: the reversed alternating tarsus, associated with a calcaneonavicular contact. This state was considered to be a synapomorphy of ‘advanced’ Toxodontia families (Notohippidae, Leontiniidae and Toxodontidae), but a further inspection of its distribution shows that it occurs throughout Mammalia. Additionally, it overlaps the serial tarsus condition as originally defined, and it probably has no functional or phylogenetic significance. Calcaneonavicular and astragalocuboid contacts are non-exclusive, and their presence within a species, genus or family is not constant. Serial and alternating imply movements of the articulations of the mid-tarsus in the transverse axis, while reverse alternating refers to a small calcaneonavicular contact that sometimes occurs in a serial condition or to a significant displacement of the tarsal articulations in a different (proximodistal) axis. The proximodistal arrangement of the joints could be functionally significant. Two new states are observed and defined: (i) ‘flipped serial’, present in Macropodidae, in which the calcaneocuboid articulation is medially displaced and significantly larger than the astragalonavicular contact, but the relationships between proximal and central elements are one to one; and (ii) ‘distal cuboid’, an extreme proximodistal displacement of the astragalonavicular joint. Serial and alternating, as originally defined (i.e. without any reference to which bone contacts which), seem to be the best states for classifying tarsal arrangement though as the disposition of distal or central bones in relationship to proximal bones. Fil: Lorente, Malena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina

Hegetotheriidae is one of the most derived families of South American notoungulates, which are known from the late Oligocene to Pliocene. Several genera of hegetotheriids have been described; most of them have been recently re-examined, but the Miocene taxa Hegetotherium and Pachyrukhos have not been revised for more than a century. Numerous species of both genera were described mainly from the Santa Cruz Formation, Santa Cruz Province, but also from the Colhuehuapian beds in Chubut Province, and the Colloncuran beds in Neuquén and Río Negro provinces, Argentina. Recently, Hegetotherium was recorded in Bolivia and Chile. Sinclair was the first reviewer to postulate some synonymies, in the first decade of the twentieth century. The present contribution provides a re-evaluation of these genera, including the study of previously unpublished materials. We conclude that Hegetotherium mirabile and Pachyrukhos moyani are the only hegetotheres in the Santa Cruz Formation (Santacrucian SALMA) with Hegetotherium novum and Pachyrukhos politus in the Colhuehuapian SALMA. Additionally, H. convexum, H. anceps, H. minum and H. andinum are proposed as synonyms of H. mirabile; H. novum is removed from Prohegetotherium; and Hegetotherium arctum is excluded from Hegetotheriidae. This taxonomic revision led to a new phylogenetic analysis of Hegetotheriidae, based on a previous data matrix, but enlarged and corrected, as some taxonomic issues concerning other genera were revealed. The analysis supports the monophyly of Hegetotheriidae and the subfamily Pachyrukhinae, as well as the monophyly of the genera Hemihegetotherium and Paedotherium, if the proposed removal of Pd. kakai from the latter is admitted. In contrast, Hegetotheriinae and Hegetotherium appear to be paraphyletic. The position of H. novum supports its removal from the genus Prohegetotherium, in which it was recently included. Fil: Seoane, Federico Damián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geologicas. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cerdeño Serrano, Maria Esperanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

A new basal notoungulate, Nanolophodon tutuca gen. et sp. nov., is described. This is represented by maxillary and dental fragments and by isolated teeth. The holotype and referred material were found at the “1968 Fissure” of the Itaborai Basin, Rio de Janeiro State, Brazil. This basin has been regarded as early Eocene in recent contributions. The generalized appearance and brachydonty of the studied specimens, together with the presence of certain typical traits (poorly developed entolophid, well-developed metacone column, etc.) indicate that N. tutuca can be considered among the group of genera traditionally known as henricosborniids, easily distinguishable from Typotheria by the absence of crista 1 and from Toxodontia by the absence of crista intermedia. It is also different from all other henricosborniids by a combination of characters, such as the presence of a long crochet, the development of two small cristae in the ectoloph, and the large paraconid, among others. In the context of a phylogenetic analysis performed, we do not find conclusive evidence about the synonymy between Itaboraitherium atavum and Othnielmarshia pristina. In turn, we question the reference of these forms as henricosborniids, based on the complex occlusal dental pattern observed in both cases. Finally, based on the observations made in the present study, we discuss the identification of the paraconid in notoungulates, which may be associated with some cusps located mesially to the metaconid and identified as pseudoparaconids in past studies.

We revise the mammal fossils from the Fray Bentos Formation previously assigned to Notoungulata, as well as some new remains recovered from levels cropping out in Corrientes Province (Argentina). In some cases, previous determinations have been completed to the species level, but others have been substantially modified, identifying different families. At present, identified taxa are: “Prohegetotherium” schiaffinoi (Hegetotheriidae), an undetermined interatheriid that is hypothesized as representing the upper teeth of Eopachyrucos ranchoverdensis, and Argyrohyrax proavus (Interatheriidae), cf. Archaeohyrax suniensis (Archaeohyracidae), cf. Mendozahippus fierensis (“Notohippidae”), a Leontiniidae indet., and some undetermined Notoungulata. The presence of Leontiniidae is based on the specimen CTES-PZ 7871, but those previously assigned to this family are herein discarded as such and reinterpreted (notohippid and undetermined taxon). The Mesotheriidae are discarded among the revised materials, but they are present in the Fray Bentos Formation in Corrientes Province with Trachytherus spegazzinianus (= Ameghinotherium curuzucuatiense). The revised sample presents affinities with the fauna from the type locality of the Fray Bentos Formation, in Uruguay, and the Deseadan assemblages from Quebrada Fiera (Mendoza Province, Argentina), Patagonia (Argentina), and Salla (Bolivia). These similarities are important from a paleobiogeographic point of view, especially by the recognition of cf. M. fierensis, a species only known from Mendoza up to now. Only the finding of new material from Fray Bentos Formation in Corrientes Province will allow us to corroborate these tentative determinations and a possible eastward extension of up-to-now exclusive taxa from Quebrada Fiera.

This contribution details new records of Notoungulata and Astrapotheria from the exposures of the Santa Cruz Formation in the Río Santa Cruz (Early-Middle Miocene; Province of Santa Cruz). The astrapothere Astrapotherium sp. Burmeister, the notoungulate toxodonts Homalodotherium sp. Flower, Nesodon sp. Owen and Adinotherium sp. Ameghino, and the typotheres Hegetotherium mirabile Ameghino, Interatherium sp. Ameghino, Protypotherium sp. Ameghino, P. attenuatum Ameghino, P. australe Ameghino and P. praerutilum Ameghino are recognized in the localities Barrancas Blancas and Segundas Barrancas Blancas. Nesodon imbricatus Owen was recorded in the former and Adinotherium ovinum (Owen) in the latter locality. The typothere Pachyrukhos moyani Ameghino was identified only in Segundas Barrancas Blancas, but with numerous specimens. Only the large ungulates Astrapotherium magnum (Owen) and Adinotherium sp. were recorded in Yaten Huageno. At a generic level, Barrancas Blancas and Segundas Barrancas Blancas only differ by the presence of Pachyrukhos Ameghino in the latter; at Yaten Huageno the Typotheria, Homalodotheriidae and Nesodon have not been recorded. The general faunal composition, including the larger samples from Barrancas Blancas and Segundas Barrancas Blancas, matches the record from the better-known Santacrucian localities from the Atlantic coast. This faunal similarity implies that similar environmental conditions prevailed in the two areas, indicating that the localities from Río Santa Cruz, as the Atlantic coastal localities, would have constituted a complex mosaic of open and closed habitats. Esta contribución involucra un reporte faunístico de los nuevos registros de Notoungulata y Astrapotheria provenientes de los yacimientos de la Formación Santa Cruz del Río Santa Cruz (Mioceno Temprano–Medio; provincia de Santa Cruz). El astrapoterio Astrapotherium sp., los notoungulados toxodontes Homalodotherium sp. Flower, Nesodon sp. Owen y Adinotherium sp. Ameghino, y los tipoterios Hegetotherium mirabile Ameghino, Interatherium sp. Ameghino, Protypotherium sp. Ameghino, P. attenuatum Ameghino, P. australe Ameghino y P. praerutilum Ameghino fueron reconocidos en Barrancas Blancas y Segunda Barrancas Blancas. Las especies Nesodon imbricatus Owen y Adinotherium ovinum (Owen) fueron identificados en la primera y en la segunda localidad, respectivamente. El tipoterio Pachyrukhos moyani Ameghino fue identificado únicamente en Segundas Barrancas Blancas, pero a través de numerosos ejemplares. Solo los ungulados de gran talla Astrapotherium magnum (Owen) y Adinotherium sp. fueron reconocidos en Yaten Huageno. A un nivel supraespecífico, Barrancas Blancas y Segundas Barrancas Blancas difieren por la presencia de Pachyrukhos Ameghino en la segunda, mientras que en Yaten Huageno los Typotheria, Homalodotheriidae y Nesodon no han sido identificados. La composición faunística general, incluyendo las grandes muestras provenientes de Barrancas Blancas y Segundas Barrancas Blancas, coincide con la registrada en las localidades Santacrucenses más conocidas de la costa Atlántica. Esta similitud faunística permite inferir, preliminarmente, similares condiciones ambientales, indicando que las localidades del Río Santa Cruz podrían haber constituido un complejo mosaico de ambientes abiertos y cerrados. Fil: Fernández, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina Fil: Muñoz, Nahuel Antu. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina

Old and new specimens from the early Miocene middle member of the Mariño Formation (Mendoza, Argentina) allow for a reinterpretation of a controversial Mesotheriidae taxon. Earlier known remains come from the Divisadero Largo locality and were, depending on the specimen, either previously described as Trachytherus? mendocensis or referred to a coeval taxon from Chile, Altitypotherium chucalensis. Based on new specimens, here described in detail for the first time, we propose that all mesotheriid material from Divisadero Largo, as well as new material from the Potrerillos locality belong to a new mesotheriid taxon. Recognition of the same taxon from these two localities establishes a sound biostratigraphic correlation. The combination of morphological characters leads to the proposal of a new generic name, Rusconitherium, for Trachytherus? mendocensis, establishing Rusconitherium mendocense New genus and New Combination. This nomenclatural act is due to the fact that T.? mendocensis, formerly thought as a Trachytheriinae from the Paleogene Divisadero Largo Formation, actually comes from the Mariño Formation and belongs to the same taxon as the new material. The missing holotype of T.? mendocensis prompts us to propose a neotype and a new diagnosis for this species, which better characterize the Santacrucian mesotheriids from Mendoza. A phylogenetic analysis does not support a close relationship between this species and Altitypotherium (or any other mesotheriine genus) counter to a previous hypothesis. An unnamed new taxon from the Chinches Formation (San Juan Province) could belong to Rusconitherium, but its full description is pending, as well as a thorough revision of most Mesotheriinae members. Sediments at Potrerillos reveal two paleoenvironmental scenarios: dune fields, influenced by volcanic events, and capillary water that provided humid conditions encouraging vegetation and fauna. Fil: Cerdeño Serrano, Maria Esperanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Vera, Bárbara Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Combina, Ana María. Universidad Nacional de La Rioja; Argentina

Here we describe three new notohippid notoungulate species from the early Oligocene-aged Tinguiririca Fauna (Tinguirirican SALMA), recovered from volcaniclastic deposits of the Abanico Formation in the central Chilean Andes, two of which are known from material sufficiently complete to warrant formal naming. These include Eomorphippus bondi, sp. nov., a form of moderate size distinguished by hypsodont incisors and cheekteeth, as well as distinctive proportions of the upper incisors. A closely similar but more diminutive form is described as Eomorphippus neilopdykei, sp. nov. A third previously unrecognized notohippid in the Tinguiririca Fauna, best represented by a large, low-crowned, lower incisor battery, almost certainly represents a new taxon, but remains too fragmentary to warrant naming now. We also propose a new binomial for a previously named notohippid, ?Eomorphippus pascuali, originally described from Gran Barranca in Argentina but which is now also recorded in Chile. This taxon, here named Rosendo pascuali, is markedly less hypsodont than E. bondi and E. neilopdykei and retains lingual cingula on at least p4-m1. As least one leontiniid notoungulate occurs in the Tinguiririca Fauna, Termastherium flacoensis, gen. et sp. nov., best represented by two partial upper cheek toothrows and a tentatively referred maxillary fragment bearing three deciduous teeth. Collectively, description of these new fossils from Termas del Flaco, Chile helps to more fully characterize the Tinguiririca Fauna, facilitating correlation and comparison to other South American land mammal faunas spanning the Eocene-Oligocene transition.

The Neogene outcrops in Northwestern Argentina have provided many fossil mammals, particularly notoungulates. However, the fossil record of the early stages of the late Miocene is scarce. The present study describes two mesotheriine specimens from Las Arcas Formation (underlying the Chiquimil Formation dated at 9.14 ± 0.09 Ma; Catamarca Province) and Saladillo Formation (dated at 10 ± 0.3 Ma; Tucumán Province), represented by a left maxillary fragment with complete M1–3 and a right isolated M3, respectively. The main feature of these pieces is their small size, significantly smaller than that of the Miocene genera Eutypotherium, Typotheriopsis, and Pseudotypotherium, recorded in Argentina. In contrast, these mesotheriines are closer to specimens known from Bolivia. The comparative analysis allows us to refer the material herein described to Plesiotypotherium aff. P. achirense and Mesotheriinae indet., with all cautions inherent to the incompleteness of the material. In turn, the paleobiogeographic implication of these new records is approached. A relationship concerning phylogenetic aspects, size, temporal range, and distribution pattern is proposed, taking into account the small size of the studied material in a temporal context of medium to large-sized mesotheriines. Fil: Armella, Matías Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentina Fil: Nasif, Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentina Fil: Cerdeño Serrano, Maria Esperanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina

A new mammalian assemblage from the Late Miocene Palo Pintado Formation in Northwestern Argentina is described. Specimens were exhumed from the lower levels of the unit cropping out at Tonco Valley, Salta Province. The association includes representatives of seven families and three orders: Cingulata (Macrochorobates, Vetelia, Euphractini gen et sp. indet. a and b), Notoungulata (Paedotherium, Protypotherium, Typotheriopsis), and Rodentia (Caviidae gen et sp. indet. a and b, Procardiomys, Protabrocoma, Prolagostomus, Lagostomus). This assemblage, together with stratigraphical information, suggests a Late Miocene age, probably intermediate between Chasicoan and Huayquerian SALMAs for the fossiliferous levels of the Palo Pintado Formation in Tonco Valley. Paleoecological data discernible from the faunal association suggest grassland and marsh communities that developed in the flood-plain setting under a seasonal climate with a conspicuous dry season. Fil: Zimicz, Ana Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Payrola Bosio, Patricio Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: del Papa, Cecilia Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina

Although the extinct Quaternary megafauna is widely recorded in northeastern Brazil, geochronological studies carried out on its fossiliferous deposits are still scarce. In this study, Electron Spin Resonance (ESR) was applied to date 12 tooth fragments of Toxodon platensis (Mammalia, Notoungulata) collected in the tank deposit of Lago do Rumo, Baixa Grande, state of Bahia, Brazil. The results obtained in the geochronological analysis performed here reveal ages from around 60 ka to 34 ka for T. platensis in Lagoa do Rumo; and, considering the integration data in the paleontological literature, our results evidence the largest time-averaging ever recorded for tank deposits: around 51 thousand years.

The fossil record from Cenozoic sediments provides a great deal of information that has direct bearing on the early assembling of modern Patagonian ecosystems. In this synthesis, we revise selected fossil marine and terrestrial records from the last 66 Ma with the aim of understanding major shifts of Patagonian biotas. From the Paleocene to the mid Eocene this region supported outstandingly diverse terrestrial assemblages that show strong connections to modern-day Australasia (e.g. gum trees, casuarinas, monotremes). Nearshore marine biotas confirm peak warmth conditions, with tropical species with Tethyan affinities. The late Eocene and early Oligocene marks the onset of a period of overall regional cooling, drying, and increasingly variable ecological conditions. The rise of palm-dominated flammable biomes in hinterlands and the prevalence of Gondwanan gallery forest (e.g. southern beeches and podocarps) along river-sides supported the existence of mosaic habitats maintained by edaphic and regional climatic conditions. This shift in landscapes reflects the evolution of a wide range of herbivorous mammals (e.g. Notoungulata, Litopterna, and Astrapotheria). The late Oligocene and early-to-mid Miocene witnessed a dramatic modification of landscapes including the incursion of high sea-level episodes, the emergence of specialized coastal (i.e. salt-marsh) plant taxa and the expansion of large herbivorous mammals with predominantly high-crowned teeth (e.g. Notoungulata: Hegetotheriidae, Interatheriidae, and Mesotheriidae). The cooling trend of this interval was interrupted by a mid-Miocene transient warming event, with the dispersion of terrestrial (e.g. platyrrhine monkeys, palms) and marine (e.g. Tuberculodinium vancampoae) elements with tropical affinity into southernmost South American regions. Seasonally-dry conditions increased towards the end of the Miocene, yet subtropical species persisted either in terrestrial (e.g. malpighs, passion vines, capybaras), and marine (e.g. Subtropical and Caribbean molluscs) environments. The increasing aridity caused by the Andean uplift wiped out most of the forest species and promoted the diversification of open-habitat species; the emergence of the current grass-dominated Patagonian Steppe occurred later on, probably during the Quaternary.

Bahia state is widely known for the presence of fossiliferous deposits of Late Pleistocene – early Holocene. Although most studies in the state have been carried out on cave environments, studies concerning natural tank deposits have been expanded in the last few years, particularly in other states of Northeast Brazil. Therefore, the present work aims to study two new natural tanks: “Lagoa das Abelhas” and “Lagoa do Rancho”, in Guanambi municipality, south-central Bahia, Brazil. The identified taxa include representatives of Xenarthra (Eremotherium laurillardi, cf. Glossotherium sp., Pachyarmatherium brasiliense, Glyptodontinae, Propraopus sulcatus, Pampatherium humboldti, and Holmesina paulacoutoi), Notoungulata (Toxodontidae), Proboscidea, Perissodactyla (Tapirus terrestris and Equus (Amerhippus) neogaeus), and Cetartiodactyla (Camelidae). The taphonomic analysis allowed the fossiliferous deposit from Lagoa das Abelhas to be classified as an ex situ assemblage, while the Lagoa do Rancho deposit was interpreted as a peripheral assemblage. Based on its paleofaunal composition, the landscape of the Guanambi region would have comprised open areas with pastures and patches with arboreal elements. The 14C radiocarbon dating results point to ages of 22,230 ± 55 years for the Lagoa das Abelhas and 16,020 ± 40 years for the Lagoa do Rancho tanks, indicating that the Guanambi paleofauna lived during the Last Glacial Maximum, in a drier phase of the Late Pleistocene.

Paedotherium was the last representative of the pachyrukhines (Notoungulata, Hegetotheriidae), a small rabbit- or caviomorph rodent-like clade, with hypsodont and simplified dentition. In contrast to the Pliocene Paedotherium species, the Miocene species are less known and mainly represented by teeth. Different systematic studies of Paedotherium based on the same set of subtle trait variations of the cheek teeth have arrived at different proposals. With the aim of testing the validity and analysing the morphological variation of Paedotherium species, and assessing the definition and diagnostic value of teeth traits, we performed a dual approach: a traditional qualitative study and exploratory geometric morphometric analyses of the upper and lower cheek teeth (both, partial and complete series). In addition, the configurations of cheek tooth shape were used as landmark characters, in combination with traditional characters, to perform a phylogenetic analysis. We propose the validity of the late Miocene P. borrelloi Zetti, and the assignment of north-western Argentinian representatives of Paedotherium to P. aff. minor. Paedotherium borrelloi is morphologically more similar and phylogenetically more closely related to the Pliocene P. bonaerense than to other Paedotherium species. Our results suggest that during the late Miocene the coexistence of two Paedotherium lineages was already established, whose main morphological differences persisted or even intensified in Pliocene representatives, supporting a more complex evolutionary scenario than previously believed. Fil: Ercoli, Marcos Darío. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Candela, Adriana Magdalena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rasia, Luciano Luis. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ramirez, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina

Quaternary continental deposits of South America are characterized by the abundance and diversity of vertebrate remains preserved in different environmental contexts. However, the studies focused on interpreting the origin of the assemblages are scarce. The taphonomic features of the mammal specimensfrom the Río Bermejo Formation, Formosa Province (Argentina), are analyzed. The bearing levels belong to the Upper Pleistocene-lower Holocene, and were interpreted as swampy deposits that filled channels of the ancient Bermejo River, an environmental context little evaluated from the taphonomic point ofview. The assemblage includes Xenarthra, Notoungulata, Carnivora, Artiodactyla and Proboscidea. The evidence suggests that the assemblage is composed by specimens preserved in the place of death or close to it, with short time of subaerial exposure and little or no transport. After burial, the specimens werealso affected by diverse processes directly related to the swamp deposits where they were buried. In this case, the taphonomic evidence, along with the sedimentary characteristics of the bearing levels allowed the recognition of the channel-fill mode for this assemblage. Also, this study provides new information for an area that was very important in the evolution of vertebrates in Northeastern Argentina since the Late Pleistocene. Fil: Méndez, Cecilia Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Montalvo, Claudia Inés. Universidad Nacional de La Pampa; Argentina Fil: Tomassini, Rodrigo Leandro. Universidad Nacional del Sur; Argentina Fil: Zurita, Alfredo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Friedrichs, Juan. Museo Provincial de Ciencias Naturales; Argentina

Until now, only one Cenozoic fossil mammal from the Chilean Precordillera (Arica and Parinacota Region) has been reported, Caraguatypotherium munozi (Mesotheriidae: Notoungulata). In this study, we describe a fourth specimen of C. munozi and a new armadillo species, Epipeltephilus caraguensis (Peltephilidae: Cingulata), both collected from a new site closer to the fossiliferous outcrops of the Caragua area (Serravallian – Tortonian). E. caraguensis differs from other members of the family in having: two sulci in the articular surface of the mobile osteoderm; having a tubular, rough and raised anterior edge; a conspicuous transverse depression; and four widely spaced foramina. This taxon represents the youngest known peltephilid from intermediate latitudes and indicates a wide geographic distribution (Patagonia to Central Andes) of the family just prior to its extinction. The new mesothere specimen is 19% larger than previous records. The revision of the dental features of C. munozi allowed the identification of an ambiguous trait in its original diagnosis, i.e. an enamel fracture was misinterpreted with the presence of a posterior sulcus on the talonid of the m3, suggesting that further taxonomic and systematic revision for the Caragua mesothere is necessary. Although the fossil record from the Caragua area is still scarce, mesotheriines seem to be abundant at this latitude, just as has been observed at several early to late Miocene sites such as Chucal (Chile), Cerdas and Nazareno (Bolivia), as well as in southern regions such as Arroyo Chasico and Mendoza (Argentina). The presence of a new peltephilid species in Caragua sustains the hypothesis of provincialism during the Miocene in intermediate latitudes. Our findings also provide further support for probable faunal movements between intermediate and higher latitudes rather than to lower ones.

El orden Notoungulata es uno de los de mayor extensión temporal y constituye el grupo de ungulados sudamericanos más abundante y diverso, en cuanto a formas y tamaño corporal. Se reconocen las familias Hernicosborniidae Ameghino y Notostylopidae Ameghino, sin relaciones claras con los demás taxones, y los subórdenes Toxodontia Owen y Typotheria Zittel. Los Toxodontia incluyen las familias Isotemniidae Ameghino, Homalodotheriidae Gregory, Leontiniidae Ameghino, Notohippidae Ameghino y Toxodontidae Gervais. Los Typotheria incluyen las familias Oldfieldthomasiidae Simpson, Archeopitheciidae Ameghino, Archaeohyracidae Ameghino, Interatheriidae Simpson, Mesotheriidae Alston y Hegetotheriidae Ameghino. Hasta el momento no han sido analizados con un enfoque biomecánico ni contrastado estadísticamente considerando una contraparte en mamíferos vivientes. En este trabajo se interpreta la mecánica de la locomoción de los taxones del orden Notoungulata. Los objetivos particulares son: a) reconocer caracteres relevantes para interpretar adaptaciones locomotoras en los Notoungulata; b) reconocer variables morfométricas en los grupos fósiles y en análogos vivientes que permitan caracterizar funcionalmente las extremidades en relación con la mecánica de la locomoción; c) evaluar la utilización de ungulados y roedores caviomorfos actuales como análogos para comparar modos de locomoción de ungulados nativos; d) realizar una primera estimación de la masa corporal de los representantes fósiles y evaluar la influencia sobre la estructura de las extremidades; y e) interpretar características locomotoras asociadas con la conformación de las superficies articulares y disposición de los miembros. Se describen los elementos óseos del esqueleto apendicular para cada uno de los taxones del orden representado con material de postcráneo, y se comparan e interpretan morfofuncionalmente dentro de cada familia, teniendo en cuenta los principales accidentes óseos y la correspondiente interpretación muscular, acorde a lo observado en mamíferos vivientes, principalmente ungulados, roedores y carnívoros. Se realiza un análisis morfométrico y morfofuncional, para el que se incluyen 94 ejemplares de mamíferos actuales, proboscídeos (2), ungulados (artiodáctilos y perisodáctilos) (40), y roedores caviomorfos (52), y 892 ejemplares representantes del orden Notoungulata. Se tomaron 113 medidas, correspondientes a longitudes funcionales, longitudes relativas a accidentes óseos, áreas articulares, diámetros de los huesos de las extremidades, y ángulos articulares; además algunas medidas dentarias. Se estima la masa corporal de los taxones sobre la base de ecuaciones alométricas construidas en mamíferos vivientes, considerando medidas del esqueleto apendicular y medidas dentarias. Se construyen 78 índices, algunos que han mostrado tener relevancia en la interpretación funcional del esqueleto apendicular y otros con posible significado funcional en la locomoción. Las variables se analizan en los grupos de mamíferos actuales (ungulados y proboscidios por un lado, y roedores por otro) para someter a prueba su significado funcional, y se utilizan para interpretar funcionalmente las variaciones morfológicas del esqueleto apendicular de los taxones fósiles. El análisis estadístico incluye correlaciones entre los índices, con la masa corporal, y análisis de componentes principales en los grupos de mamíferos vivientes y fósiles. Se compara el promedio de los índices para cada uno de los taxones fósiles dentro de cada familia, se evalúa su utilización para la identificación de los géneros con material de postcráneo y se interpretan acorde a los resultados de los análisis previos.

Interatherium supernum Ameghino, 1887b Holotype. Not located, probably lost. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1887b: 15). ��� Tama��o mayor que el de la precedente [I. rodens]. Longitud de las siete muelas inferiores, 29 mm. Muelas inferiores m��s anchas. m3 con el l��bulo tercero apenas aparente ���. English translation. Larger in size than the previous species [I. rodens]. Length of the seven lower cheek teeth, 29 mm. Lower cheek teeth wider. m3 with the third lobe barely apparent. Comments. Ameghino (1887b) founded and characterised this species based on a mandibular fragment with at least all of its cheek teeth, but he did not illustrate it. Later, Ameghino (1889, plate 15: figs. 17���19) notably expanded the original description based on fragmented mandibles and, mainly, a partial maxilla, all of them collected by C. Ameghino in Santa Cruz River in 1887 (Fernicola 2011). In contrast to the original description, Ameghino���s catalogue states that the maxilla MACN-A 424 is ��� tipo 1 ��� (1 st type), an old and informal term used to refer to an holotype (C. Scioscia, pers. comm.), and that the partial mandibles MACN-A 357 (alveoli of right i1 and left i1 ���dp1 with complete p2���m1 series), MACN-A 358 (alveoli of left i1 ���dp1 and complete p2���3 series) and MACN-A 359 (broken left p2 and complete p3���m2 series) are ��� tipo 2 ���, an informal and antique expression used to refer to a paratype (C. Scioscia, pers. comm.). Within the Ameghino Collection, MACN-A 424, MACN-A 357 and MACN-A 540 (right fragmented mandible with dp2���m1) correspond to figures 17, 18 and 19, respectively, of Ameghino���s Atlas (1889: plate 15). Nevertheless, none of these mandibular fragments is the holotype of the species, because they do not, either alone or combined, recreate the original dp1���p2���m3 series. Besides, as they do not present any evidence of recent break, it is inferred that they have not lost any dental piece through time in the collection. In addition, these materials do not present wide lower molariforms as originally described by Ameghino (1887b). Regarding the maxilla MACN- A 424, it is also discarded as type material due to the fact that Ameghino (1887b) only described lower dentition of I. supernum. As a matter of fact, if he had had the maxilla at hand, he would have compared and contrasted I. supernum and I. rodens not only based on lower teeth but also on upper teeth, which he did in detail in 1889, when he even recognised that the lower dentition of I supernum did not present anything in particular except its size and more continuous anterior dentition. On the other hand, Mones (1986) indicated MLP 12-1846 (right mandibular fragment with p4���m3), MLP 12- 1878 (incomplete left maxilla with P3���M2), MLP 12-1879 (right maxilla with broken P3, P4���M2, and broken M3), MLP 12-1885 (left mandibular fragment with p3���m1), MLP 12-1886 (right mandibular fragment with dp4���m2), MLP 1887 (right mandibular fragment with p3���m1) and MLP 12-1921 (left mandibular fragment with p4���m2 and broken m3) as the type specimens of I. supernum. In the collection of MLP, all these specimens are labelled as paratypes of I. supernum. However, MLP 12-1878 and MLP 12-1879 are discarded as type materials because they are maxillae. The same conclusion is inferred for the fragmented mandibles, because they do not exhibit the tooth row mentioned in the original diagnosis (Ameghino 1887b) and there is no evidence of any recent break. In the case of MLP 12-1846, which is the only specimen with complete m3, it does not exhibit the characteristics originally mentioned by Ameghino (1887b). It is worth mentioning that when comparing the labels of these specimens (indicating them as paratypes) with the Old Collections catalogue, which was written 30 years before the labelling (M. Reguero, pers. comm.), we noticed that there are many inconsistencies that make us question the veracity of the labelled information. On the one hand, none of the materials labelled as ��� paratype ��� is indicated as such in the Old Collections catalogue; in fact, the term is a modern expression that was never used by Florentino Ameghino. On the other hand, in contrast to the labels, there is no information in Old Collections catalogue concerning the collector and/or provenance of these specimens. Due to all of these facts and that there is no original tag that validates their status as paratypes or even confirms that any of these materials was actually collected by Carlos Ameghino in 1887 and used by Florentino Ameghino to describe I. supernum, they are all rejected as the paratypes of the species. In summary, the holotype of I. supernum has not been located either in MACN-A and MLP collections or in any other collection revised by mean of photographs (e.g., AMNH, FMNH and YPM)., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 200-201, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1887 b) Enumeracion sistematica de las especies de mamiferos fosiles coleccionados por Carlos Ameghino en los terrenos eocenos de la Patagonia austral y depositados en el Museo La Plata. Boletin del Museo de La Plata, 1, 1 - 26.","Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Interatherium rodens Ameghino, 1887a Interatherium rodens Moreno, 1882: 117, nomen nudum. Ameghino, 1887a: 63, ex Moreno 1882. Holotype. MLP 12-2826 (Fig. 1 A), right maxilla with alveolus of dP1, dP2 and P3���M3 series. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1887a: 63). ��� Talla comparable a la de una liebre. Paladar profundo, c��ncavo, liso y con un peque��o agujero palatino en la sutura anterior del palatino con el maxilar. Sutura anterior del palatino con el maxilar al nivel del P4. ��ltimo molar superior implantado con su eje mayor en direcci��n de la serie dentaria. Ap��fisis cigom��tica del maxilar con un proceso descendiente suborbitario. ��rbita del ojo, grande. Serie dentaria superior formando un arco muy pronunciado. [���] De este animal s��lo se conoce el maxilar superior derecho con todas sus muelas, menos el pm. 1 , recogido por Moreno durante su viaje de 1876���1877 ���. English translation. Size similar to that of a hare. The palate is deep, concave, smooth and presents a small palatine foramen anterior to the palatine-maxilla suture. This suture is at the level of P4. The last upper molar is implanted with its major axis in the same direction as the dental series. The zygomatic process of the maxilla presents a suborbital descending process. The orbits are large. Upper dental series forms a very pronounced arch. [...] This animal is only known by a right maxilla with all its cheek teeth, except for its P1, which has been collected by Moreno during his 1876 ��� 1877 exploration. Comments. Ameghino (1887a) described this species based on a right maxilla collected by Francisco P. Moreno in 1876 ��� 1877. The same year, Ameghino (1887b) included other characteristics regarding I2 ��� C and provided the length of dp1���p2���m3 series. Subsequently, Ameghino (1889: plate 15, figs. 20���26) significantly expanded his previous descriptions by studying some mandibular and cranial fragments that he also illustrated, including a maxilla herein reproduced (Fig. 1 B). Florentino indicated that this specimen was in fact the maxilla used by Moreno to erect I. rodens and that it was deposited in the MLP at that time. Despite Ameghino���s acknowledgment regarding the status of the maxilla, he stated in his personal catalogue that MACN-A 377 to MACN-A 387 were the type materials of I. rodens. In contrast, Mones (1986) indicated the maxilla MLP 12-2826 as the type material of the species. This specimen is in fact the maxilla originally described and later illustrated by Ameghino (1887a, 1889) and, as a result, it is confirmed as the holotype of I. rodens. On the contrary, MACN-A 377 to MACN-A 387 are discarded as paratypes of I. rodens because, when reconstructing the history of these materials, they were given to Florentino by his brother Carlos in September of 1887, that is after the publication on the maxilla in April of 1887., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 198-199, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1887 a) Observaciones generales sobre el orden de mamiferos extinguidos sub-americanos llamados Toxodontes (Toxodontia) y sinopsis de los generos y especies hasta ahora conocidos. Anales del Museo de La Plata, 1 (1), 1 - 66.","Moreno, F. P. (1882) Patagonia, resto de un antiguo continente hoy sumergido. Contribuciones al estudio de las colecciones del Museo Antropologico y Arqueologico de Buenos Aires. Anales de la Sociedad Cientifica Argentina, 14, 97 - 131.","Ameghino, F. (1887 b) Enumeracion sistematica de las especies de mamiferos fosiles coleccionados por Carlos Ameghino en los terrenos eocenos de la Patagonia austral y depositados en el Museo La Plata. Boletin del Museo de La Plata, 1, 1 - 26.","Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Interatherium dentatum Ameghino, 1894a Holotype. MACN-A 9863 (Fig. 1 E), anterior cranial fragment and an almost complete mandible in anatomical connection. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� Par la taille se rapproche de 1��� I. supernum; il s'en distingue pour poss��der une pr��molaire de plus �� la m��choire sup��rieure, c'est-��-dire cinq au lieu de quatre. Les deux premi��res pr��molaires sont coniques, la premi��re ou ant��rieure ��tant s��par��e de la deuxi��me. La s��rie dentaire sup��rieure compl��te occupe un espace de 41 mm ���. English translation. It is close to I. supernum by its size; it differs from it in having an additional premolar in the maxilla, which means five instead of four. The first two premolars are conical, the first (or anterior) being separated from the second. The complete upper dental series occupies a space of 41 mm. Comments. Ameghino (1894a) did not add any illustration to the original description. No specimen is indicated as the type material of I. dentatum in Ameghino���s catalogue, and Mones (1986) wrote ���MACN?���, which means doubts or lack of information regarding the type that could be housed at the MACN. There are three specimens assigned to I. dentatum within the Ameghino Collection: the articulated skull and mandible MACN-A 9863, and two fragmented maxillae, MACN-A 9864 and MACN-A 9865, corresponding to two different individuals. These maxillae lack its anterior portion, so the region that should contain the extra premolar is not preserved in any of them; as the areas of breakage are not recent, both specimens are discarded as the type. Instead, MACN-A 9863 matches the original description (Ameghino 1894a) as it presents an extra alveolus between C and dP1, which is separated from the latter by a distinct diastema. The length of left I1 ���M3 series (41.3 mm) also matches the only measurement provided by Ameghino (1894a). Consequently, MACN-A 9863 is considered the holotype of I. dentatum., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 202, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus hegetotheroides Ameghino, 1894a Holotype. MACN-A 9855 (Figs. 6 D���E), anterior cranial fragment, and MACN-A 9856 (Figs. 6 F���G), an incomplete mandible, both of the same individual. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 17). ��� Cette esp��ce se distingue par le grand d��veloppement de la paire d'incisives internes sup��rieures (i. 1 ), comparables sous ce rapport �� celles du genre Hegetotherium. Ces incisives sont convexes en avant, concaves en arri��re, et avec la surface de la couronne en arc de cercle. La deuxi��me incisive est petite, et la troisi��me incisive ainsi que la canine sont atrophi��es. La partie ant��rieure du cr��ne est tr��s raccourcie et proportionnellement tr��s large. La couronne de chacune des incisives internes a 5 mm. 5 de diam��tre transverse en ligne droite. Le palais au niveau des canines a 13 mm. de largeur, et la distance du bord ant��rieur de la p. 1 au coin interne de l'i. 1 est de seulement 46 mm ���. English translation. This species is distinguished by the great development of the internal upper incisors (I1), similar in this aspect to those of the genus Hegetotherium. These incisors are labially convex, lingually concave, and with an arched surface of the crown. The second incisor is small, and the third incisor and the canine are atrophied. The anterior part of the skull is very short and proportionally very broad. The crown of each internal incisor measures 5 mm. 5 of transverse diameter in a straight line. The palate is 13 mm wide at the level of the canines, and the distance from the anterior part of P1 to the internal part of I1 is only 46 mm. Comments. Ameghino (1894a) did not illustrate any specimen of this species. According to Ameghino���s catalogue and Mones (1986), MACN-A 9855 (anterior portion of a skull) and MACN-A 9856 (incomplete mandible), which belong to the same individual, are the type specimens of the species. The measurements of MACN-A 9855 (MDL of I1 = 5.5���5.7 mm; width of the palate at the C level = 13.2 mm; length of I1 ���dP1 = 16.3 mm) match approximately those provided by Ameghino (1894a). Therefore, MACN-A 9855 and MACN-A 9856 are confirmed as the holotype of Ic. hegetotheroides., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 215-216, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus senilis Ameghino, 1894a Holotype. MACN-A 3596 (Fig. 4 C), incomplete skull, MACN-A 3597 (Fig. 4 D), complete mandible, and MACN-A 3598 to MACN-A 3630, postcranial elements, all of them from the same individual. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 15). ��� Cette esp��ce est de la taille de l��� I. extensus, mais un peu plus robuste; elle se distingue facilement par la deuxi��me pr��molaire inf��rieure qui n'est pas bilob��e, mais de contour elliptique et par cons��quent sans sillon vertical, ni sur la face interne ni sur l'externe. La troisi��me et quatri��me pr��molaire inf��rieure ainsi que les vraies molaires, sont plus larges que dans les autres esp��ces. La deuxi��me pr��molaire sup��rieure est aussi de contour elliptique et sans sillon. Il y a un diast��me assez long entre la canine inf��rieure et la premi��re pr��molaire. Longueur des sept molaires inf��rieures, 32 mm ���. English translation. This species is of the size of Ic. extensus, but it is a little more robust; it is easily distinguished by the second lower premolar that is not bilobated but elliptical and, subsequently, without internal and external vertical grooves. The third and fourth lower premolars, as well as the true molars, are wider than in the other species. The second upper premolar is also elliptical and without groove. There is a rather long diastema between the lower canine and the first premolar. Length of the seven lower molars, 32 mm. Comments. Ameghino (1894a) did not illustrate any specimen of this species. According to Ameghino���s catalogue and Mones (1986), MACN-A 3596 to MACN-A 3630, an almost complete individual, constitute the type specimen of this species. The mandible MACN-A 3597 and the skull MACN-A 3596 present the respective p2 and P2 elliptical in cross section with very shallow lingual and labial grooves. In addition, the dimensions of MACN-A 3597 (length of the diastema c���dp1 = 2 mm; length of the lower tooth row = 32 mm) match those provided by Ameghino (1894a). Therefore, MACN-A 3596 to MACN-A 3630 are confirmed as the holotype of Ic. senilis., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 209, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus robustus Ameghino, 1891 Holotype. MACN-A 3454 (Fig. 4A) to MACN-A 3505, complete skull and mandible of the same individual, with associated postcranial elements. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1891: 393). ��� Del tama��o de Icochilus extensus, del que se distingue por el cr��neo m��s ancho y por los frontales que se prolongan adelante entre los nasales ���. English translation. Of the same size as Icochilus extensus, from which it is distinguished by presenting a wider skull and the frontals extended forward between the nasals. Comments. Ameghino (1891: 393, figs. 95���97) briefly described this species in a footnote, stating that he had the entire skeleton of an individual. He also illustrated a foot, a right hand and an almost complete skull. According to Ameghino���s catalogue and Mones (1986), MACN-A 3454 to MACN-A 3505, an almost complete individual, constitute the type specimen of the species. MACN-A 3454 is indeed the illustrated complete skull (Ameghino 1891: fig. 97), herein reproduced (Fig. 4 B), although it has suffered many breaks. Regarding the right manus and foot, only some elements (basipodia, metapodia and phalanges) are present. At the beginning of the current study, all of these materials were in different uncovered containers, so it is assumed that different elements have been missed over the years. Therefore, MACN 3454 to MACN-A 3505 are confirmed as elements of the holotype of Ic. robustus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 209, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Interatherium brevifrons Ameghino, 1894a Holotype. Not located, probably lost. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� Esp��ce de taille beaucoup plus petite que le I. rodens et avec toute la denture en s��rie continue, sans diast��mes. La partie ant��rieure du cr��ne est tr��s raccourcie. L'i. 1 est tr��s grande et les i. 2 et 3 tr��s petites. La canine est bien d��velopp��e. Longueur de la partie ant��rieure de l'i. 1 �� la partie post��rieure de la m 3 , 27 mm ���. English translation. Species much smaller in size than I. rodens and with all the dentition in continuous series, without diastemata. The anterior part of the skull is very short. I1 is very large and I2���3 are very small. The canine is well developed. Length from the anterior part of I1 to the posterior part of m3, 27 mm. Comments. Ameghino (1894a) did not add any illustration to the original description of the species. According to Ameghino���s catalogue, the cranial fragment MACN-A 3440 is the type specimen of I. brevifrons. Instead, Mones (1986) indicates the fragmented maxilla MACN-A 3441 as such. MACN-A 3440 does not match the original description because it does not exhibit a complete dental series and it presents two diastemata, anterior and posterior to the upper canine. Therefore, it is discarded as the type specimen of the species. On the other hand, MACN-A 3441 can neither be considered the type material, because it is a very fragmented specimen with only three molariforms (Ameghino���s catalogue indicates ��� tres muelas ��� [three cheek teeth], so there is no option of having lost any dental piece through time). Unfortunately, no material that matches the original description (Ameghino 1894a) was located within the studied collections., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 201, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Interatherium Ameghino, 1887a Interatherium Moreno, 1882: 117, nomen nudum. Ameghino, 1887a: 63, ex Moreno 1882. Type species. Interatherium rodens Ameghino, 1887a: 63., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 198, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1887 a) Observaciones generales sobre el orden de mamiferos extinguidos sub-americanos llamados Toxodontes (Toxodontia) y sinopsis de los generos y especies hasta ahora conocidos. Anales del Museo de La Plata, 1 (1), 1 - 66.","Moreno, F. P. (1882) Patagonia, resto de un antiguo continente hoy sumergido. Contribuciones al estudio de las colecciones del Museo Antropologico y Arqueologico de Buenos Aires. Anales de la Sociedad Cientifica Argentina, 14, 97 - 131."]}

Icochilus truncus Ameghino, 1894a Holotype. MACN-A 3635 (Figs. 5 J���K), right fragmented mandible with alveoli of i1 ���dp1 and the series p2���m1. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 16). ��� A peu pr��s de la m��me taille que l��� I. extensus. Elle se distingue par la pr��sence de la premi��re pr��molaire inf��rieure tr��s petite, et par l'absence de la canine inf��rieure. A la place de la canine il y a un diast��me assez ��tendu qui s��pare l'incisive externe de la premi��re pr��molaire ���. English translation. Size almost the same as Ic. extensus. It is distinguished by the presence of a very small first lower premolar, and by the absence of the lower canine. In the place of the lower canine there is a rather extensive diastema that separates the external incisor from the first premolar. Comments. Ameghino (1894a) did not add any illustration to the brief description of I. truncus. According to Ameghino���s catalogue and Mones (1986), MACN-A 3635, a broken symphysis with a fragmented right mandibular ramus, is the type material of the species. This specimen has a small alveolus of dp1 and a diastema between i3 and dp1, whose length (2.2 mm) falls within the range (1 to 3 mm) that Ameghino provided for any gap between adjacent teeth (Ameghino 1894a: 15���18). These characteristics are consistent with Ameghino���s (1894a) description and, consequently, MACN-A 3635 is confirmed as the holotype of Ic. truncus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 213, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus rotundatus Ameghino, 1889 Syntypes. MACN-A 371 (Fig. 3 N), incomplete left maxilla with P3���M3; MACN-A 372 (Fig. 3 O), left mandibular fragment with p3���m1. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1889: 473���474). ��� La talla de esta especie es apenas un poco menor que la del I. extensus, y con muelas que re��nen en parte los caract��res de las tres precedentes. Los premolares superiores tienen las dos aristas perpendiculares d�� la parte anterior de la cara externa, apenas un poco desiguales, la segunda algo mas desarrollada que la primera, pero sin tomar la forma de columna saliente que presenta en los premolares del I. extensus. Adem��s, detr��s de la segunda arista existe la depresi��n �� surco perpendicular medio, que falta en los mismos dientes de la especie mencionada. Los verdaderos molares presentan las dos aristas anteriores casi confundidas, con la ranura que las separa poco profunda �� rudimentaria, pero sin que se levanten tanto encima de la superficie de la cara externa como en el I. excavatus. Detr��s de esta arista, viene la depresi��n perpendicular mediana, bastante ancha, pero poco profunda. La ��ltima muela superior es apenas un poco mas peque��a que la pen��ltima y casi del mismo ancho. La s��rie dentaria es ligeramente arqueada. [���] De la mand��bula inferior conozco un fragmento de la rama horizontal del lado izquierdo, con los dos ��ltimos premolares y el primer verdadero molar. Cada muela consta de dos prismas el��pticos casi iguales, apenas un poco mas angostos sobre el lado interno, con su di��metro mayor en sentido transversal. El p. 3 tiene 0 m 0 0 35 de di��metro ��ntero-posterior y 0 m 0 0 25 de di��metro transverso. El p. 4 y el m. 1 tienen cada uno 4 mil��metros de di��metro ��ntero-posterior y 3 mil��metros de di��metro transverso. El agujero mentoniano posterior es de tama��o mucho mayor que en las otras especies, pero est�� igualmente colocado debajo de la parte anterior del p. 4 . La rama horizontal debajo del p. 4 tiene 17 mil��metros de alto ���. English translation. This species is slightly smaller in size than Ic. extensus, and presents cheek teeth that partially combine the characters of the preceding three species. Upper premolars have the two antero-external perpendicular edges slightly dissimilar; the second is somewhat more developed than the first, but without taking the form of a protruding column as in Ic. extensus. In addition, behind the second edge there is a median and perpendicular depression or sulcus, which is absent in the same teeth of the already mentioned species. True upper molars present the two anterior edges nearly confused in a single column, with the groove that separates them being shallow or rudimentary, but without rising above the surface of the external face as much as in Ic. excavatus. Behind this edge, there is the median perpendicular depression fairly broad but shallow. The last upper molar is just a little smaller than the second molar and almost of the same width. The dental series is slightly arched. [...] I know from the mandible a fragment of the left horizontal ramus, with the last two premolars and the first true molar. Each cheek tooth consists of two almost equal and elliptical prisms, just a little narrower on the inner side, with its greater diameter in transverse direction. The p3 has 0.0035 m of antero-posterior diameter and 0.0025 m of transverse diameter. The p4 and m1 have 4 millimetres of antero-posterior diameter and 3 millimetres of transverse diameter. The posterior mental foramen is much larger in size than in the other species, but it is also placed below the anterior part of p4. The horizontal ramus below p4 is 17 millimetres high. Comments. Ameghino (1889: 473���474) erected and described this species based on a maxilla and a mandible, both incomplete (Ameghino 1889, plate 15: figs. 15���16). Later, Ameghino (1894a: 15) extended the original description based on a skull that he did not illustrate. According to Ameghino���s catalogue and Mones (1986), the incomplete skull MACN-A 3588 is the type specimen. MACN-A 3588 corresponds to the skull described by Ameghino (1894a), because it lacks the upper canine and exhibits a long diastema between I3 and dP1. However, it does not match any of the illustrations provided by Ameghino (1889, plate 15: figs. 15���16) and does not exhibit the diagnostic characteristics stated in the original description. Consequently, MACN-A 3588 is neither the holotype nor part of the type series of the species. On the other hand, MACN-A 371, left maxillary fragment with P3���M3, and MACN-A 372, left mandibular fragment with p3���m1, match the original illustrations (Ameghino 1889: plate 15, figs. 15���16), which are herein reproduced in Figures. 3 P���Q. It is worth mentioning that it cannot be guaranteed that both specimens belong to the same individual because they do not articulate to each other and there is no mention of this in Ameghino���s catalogue���as he used to do when this was the case���. Therefore, MACN-A 370 and MACN-A 371 are considered here as the syntypes of Ic. rotundatus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 208-209, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Notoungulata Roth, 1903 Typotheria Zittel, 1893, Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 198, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Roth, S. (1903) Los ungulados sudamericanos. Anales del Museo de La Plata, 5, 1 - 36.","Zittel, K. A. (1893) Handbuch der Palaeontologie. Vol 4. Vertebrata (Mammalia). Oldenbourg, Munchen, 293 pp."]}

Icochilus ulter Ameghino, 1899 Holotype. MACN-A 11601 (Figs. 6 H���I), right mandibular fragment with p3���m3 and left mandibular fragment with p4���m1 series. Age and provenance of the type material. Astrapothericulan beds (presumably the Pinturas Formation), early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1899: 5). ��� De la talla del Icochilus extensus, pero de rama mandibular m��s alta (20 mil��metros debajo de la quinta muela) ���. English translation. With the size of Icochilus extensus, but with a highest mandibular ramus (20 millimetres below the fifth molar). Comments. Ameghino (1899) briefly described this species without illustrating it, but he did not mention it in his catalogue. There is no specimen indicated as type of Ic. ulter in the Ameghino Collection. Despite this, Mones (1986) indicated, but with doubts, ���MACN-A 10601?��� as type specimen; however, this specimen is also indicated by the author as the type of the isotemnid Eochalicotherium crassidens. MACN-A 10601 is in fact a lot constituted by three mandibular fragments���with one tooth each���that belong to the latter species; consequently, it is discarded as the holotype of Ic. ulter. On the other hand, the lot MACN-A 11601, which is composed of two mandibular fragments of the same individual, with right p3���m3 and left p4���m1, is the only material assigned by F. Ameghino to Ic. ulter within the Ameghino Collection. The right fragment matches the only measurement (length of the mandibular ramus below m1 = 20 mm) given by Ameghino (1899). It is worth mentioning that there are two pieces of paper inside the container with Ameghino���s handwriting: one that reproduces the original description of the species and another with the name ��� Icochilus ulter ���. In the latter, it is also written ���10601��� but with someone else���s handwriting (probably from M. Soria; A. Kramarz, pers. comm.), and the first ���0��� was crossed out and replaced by ���1���; it is very likely that this mistake led Mones to mention ���MACN-A 10601?��� as the type of the species. As a result, MACN-A 11601 is identified as the holotype of Ic. ulter., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 216, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1899) Sinopsis geologico-paleontologica de la Argentina. Suplemento (Adiciones y correcciones). Imprenta La Libertad, La Plata, pp. 1 - 13.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus extensus Ameghino, 1889 Lectotype (this contribution). MACN-A 1083 (Figs. 2 A���B) and MACN-A 1084 (Figs. 2 C���D), an almost complete skull and mandible with complete dentitions, both belonging to the same individual. Paralectotypes (this contribution). Four isolated teeth, not located (see below). Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1889: 471���472). ��� Esta es la especie de mayor tama��o, cuya talla era un poco superior �� la del conejo. Los premolares 2 , 3 y 4 se distinguen f��cilmente de los de las dem��s especies, por presentar sobre la parte anterior de la cara externa dos aristas estrechas separadas por una ranura angosta y profunda; de estas dos aristas, la anterior que forma el ��ngulo ��ntero-externo de cada diente es mas peque��a y mas baja, y la posterior mas ancha y considerablemente mas elevada tomando la forma de una columna perpendicular saliente. La parte posterior externa detr��s de la columna mencionada es mas baja y plana, uni��ndose �� la cara posterior formando un ��ngulo redondeado. Los verdaderos molares superiores tienen las dos aristas de la parte anterior de la cara externa mas estrechas y de tama��o mas igual, sin que la segunda tome la forma de columna perpendicular saliente. Detr��s de esta segunda ��rista viene una depresi��n perpendicular colocada sobre la mitad del ancho de la cara externa de la muela, de fondo c��ncavo pero poco profunda. Cada uno de los verdaderos molares superiores presenta sobre el borde externo de la corona dos c��spides �� cerros puntiagudos, formados por el prolongamiento de las ondulaciones convexas perpendiculares de la cara externa. En la mand��bula inferior, los dos l��bulos que forman cada muela, son de forma mas distinta entre s�� que en las otras especies; el l��bulo anterior tiene el lado interno mucho mas estrecho y en forma de arista perpendicular angosta y saliente dirijida hacia atr��s, y el lado externo mas ancho y redondeado, con su eje mayor dirijido oblicuamente de afuera hacia adentro y de adelante hacia atr��s, presentando la cara posterior de un ancho considerable; el l��bulo posterior es tambi��n igualmente muy estrecho sobre el borde interno y mas grueso sobre el externo, pero presenta su parte anterior que se une al l��bulo que lo precede considerablemente mas angosta que la posterior. La mand��bula inferior presenta tres agujeros mentonianos, el anterior mas grande, colocado debajo de la barra que separa el p. 1 del c. 1 en el punto en que la s��nfisis se comprime transversalmente para tomar la forma de pico, el segundo mucho mas peque��o est�� colocado debajo del p. 2 , y el tercero igualmente peque��o, se encuentra debajo de la parte anterior del p. 4 . La cara externa de la rama horizontal debajo de los premolares es gruesa y convexa. La rama ascendente presenta el borde anterior con la base que sale del lado externo de la ��ltima muela levant��ndose hacia arriba formando una peque��a curva c��ncava, pero su parte superior que constitu��a la ap��fisis coronoides se inclina h��cia adelante ���. English translation. This is the largest species, being a little larger in size than a rabbit. P2���4 are easily distinguishable from those of the other species, because they have two narrow edges separated from each other by a narrow and deep groove on the antero-external face; of these two edges, the anterior one, which forms the anteroexternal angle of each tooth, is smaller and lower, while the posterior is wider and considerably higher resembling a perpendicular projecting column. The postero-external region behind this column is lower and flat, joining the posterior face in a rounded angle. M1���3 also presents two antero-external edges but both are narrower and of equal size, and the posterior edge does not take the form of a perpendicular projecting column. Behind this second edge, there is a perpendicular depression, concave but shallow, placed about half the width of the external face of the molar. Each molar has two pointed cusps or hills on the external margin of the crown which are formed by the prolongation of the convex and perpendicular undulations of the external face. In the mandible, the two lobes that constitute each tooth, are more distinct from each other than in the other species; the inner side of the anterior lobe is much narrower than the external and similar to a narrow, perpendicular and protruding edge which directs backwards, whereas the external side is broader and rounded with its major axis obliquely directed, with the posterior face being considerable wide; the posterior lobe is also very narrow on the inner face and thicker on the external, but the anterior part that joins the preceding lobe is considerably narrower than the posterior lobe. The mandible has three mental foramina, the anterior is the largest and it is placed below the diastema that separates p1 from c at the point where the symphysis is transversely compressed acquiring the shape of a beak, the second is much smaller in size and it is placed below p2, and the third is equally smaller and is placed below the anterior margin of p4. Below the lower premolars, the external face of the horizontal mandibular ramus is thick and convex. The ascending ramus of the mandible presents its anterior border with the base that emerges from the external side of m3 rising upwards forming a small concave curve, but its upper part, which constitutes the coronoid process, slopes forwards. Comments. Ameghino (1889: 471���472, plate 15: figs. 4���5) described and illustrated this species based on a partial skull and mandible of the same individual, along with four isolated teeth���I1, right upper premolar, right upper molar and left lower molariform���(Ameghino 1889, plate 15: figs. 6���9). According to Ameghino���s catalogue and Mones (1986), the skull MACN-A 1083 and the mandible MACN-A 1084 are the type specimens of Ic. extensus. Following Ameghino���s catalogue, both are part of the same animal, which is confirmed by us because they articulate to each other. MACN-A 1083 and MACN-A 1084 correspond to figures 4 and 5, respectively, of the Atlas (Ameghino 1889: plate 15), and are herein reproduced (Figs. 2 E���H). The isolated teeth (Ameghino 1889: plate 15, figs. 6���9), which were not even mentioned in the written catalogue, were not located in the collection and, due to the fact that MACN-A 1083 and MACN-A 1084 already exhibit these teeth, we conclude that they do not belong to the same individual as the skull and mandible; nevertheless, these teeth would be part of the original syntypes. As the original diagnosis was based on the characteristics of the skull and mandible, we designate MACN-A 1083 plus MACN-A 1084 as the lectotype of Ic. extensus. Consequently, the remaining syntypes become paralectotypes (ICZN 2000: Art. 73.2.2)., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 203-205, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625.","ICZN (2000) Codigo internacional de nomenclatura zoologica. 4 th edition, CSIC-MNCN Madrid, Caja Espana, The International Comission on Zoological Nomenclature and Sociedad de Amigos del MNCN (eds), Madrid, 156 pp."]}

Icochilus trilineatus Ameghino, 1894a Syntypes. MACN-A 3633 (Fig. 5 B), fragmented left maxilla with M2; and MACN-A 3651 to MACN-A 3657 (Figs. 5 C���H), isolated cheek teeth. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 16). ��� Cette esp��ce est de la m��me taille que l��� I. extensus, dont elle se distingue facilement aussi bien que des autres esp��ces, par la forme de ses molaires et pr��molaires sup��rieures. Chacune de ces dents porte sur sa face externe un sillon large et profond qui la divise en deux lobules, et sur chaque lobule il y a un sillon ��troit et profond qui le divise en deux colonnettes verticales; on voit ainsi sur la face externe de chaque dent, quatre colonnettes s��par��es par trois sillons, dont celui du milieu beaucoup plus large et les autres deux tr��s ��troits ���. English translation. This species has the same size as Ic. extensus, from which it is easily distinguished, as well as from the other species, by the morphology of its upper molars and premolars. Each tooth presents a broad and deep groove on its external face, which divides it into two lobules, and on each lobule there is a narrow and deep groove that divides it into two vertical columns; as a result, the external face of each tooth exhibits four columns separated by three grooves, the second being the widest whereas the other two are very narrow. Comments. Ameghino (1894a) did not illustrate this species. According to Ameghino���s catalogue and Mones (1986), MACN-A 3633, a small maxillary fragment with M2, is the type specimen of the species. The ectoloph of this M2 exhibits three perpendicular grooves, one in the middle and one at each lateral lobe, resulting in an ectoloph with four columns as indicated by Ameghino (1894a). Nonetheless, when describing the species, Ameghino (1894a: 16) alluded to the form of its upper molars and premolars, which implies that he had more than one tooth at hand, and therefore MACN-A 3633 cannot be the only type specimen. In this context, in the Ameghino Collection, the lot MACN-A 3651 to MACN-A 3657 contains six isolated teeth (instead of seven as corresponding inventory numbers), five of which (two M3, and three upper molariforms, probably P4 and/or M1/2) show the characteristics mentioned by Ameghino (1894a); thus, we consider them as part of the type series. As the specimens in the lot lack individual labels, it is not possible to identify which is the missing seventh tooth. Therefore, MACN-A 3633 and MACN-A 3651 to MACN-A 3657 (one currently missing) are considered the syntypes of Ic. trilineatus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 211, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Interatherium interruptum Ameghino, 1894a Holotype. MACN-A 3445 (Fig. 1 D), left maxilla with the alveolus of dP1, and series dP2���3 and P4���M3. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� De la taille de 1��� I. supernum. Cette esp��ce se distingue facilement par la pr��sence de la premi��re pr��molaire sup��rieure qui est plac��e contre la partie ant��rieure de la deuxi��me, et par la disparition compl��te de la canine. Il y a une longue barre qui s��pare la premi��re pr��molaire de l'incisive externe; le bord de cette barre porte un sillon longitudinal profond qui suit la m��me direction de la s��rie dentaire. Longueur des sept molaires sup��rieures, 25 mm ���. English translation. With the same size as I. supernum. This species is easily distinguished by the presence of the first upper premolar that is placed against the anterior part of the second, and by the complete absence of the upper canine. There is a long diastema that separates the first premolar from the external incisor; the margin of this diastema shows a deep longitudinal groove that has the same direction as the dental series. Length of the seven upper molars, 25 mm. Comments. Ameghino (1894a) did not illustrate this species. According to Ameghino���s catalogue and Mones (1986), the left maxilla MACN-A 3445 is the type specimen of the species. This material lacks the canine and, instead, exhibits a long diastema placed anteriorly to the alveolus of dP1 (L = 4.1 mm). It also shows the groove described by Ameghino, and the length of dP1���M3 is 24.8 mm. All of this coincides with Ameghino���s (1894a) description and, consequently, MACN-A 3445 is confirmed as the holotype of I. interruptum., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 202, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus excavatus Ameghino, 1889 Syntypes. MACN-A 9681 (Fig. 3 A), incomplete right maxilla with alveoli of C and dP1, and series P2���M3; MACN-A 177 (Figs. 3 B���C), mandibular symphysis with alveoli of both i1 and left series i2 ���p2; MACN-A 178 (Figs. 3 D���E), left mandibular fragment with c���m1; and MACN-A 179 (Fig. 3 F), right partial maxilla with two molariforms (probably M1���2). MACN-A 180 (maxillary or mandibular fragment according to the catalogue) and an unnumbered isolated m3 (originally illustrated) are currently missing. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1889: 472���473). ��� Esta especie era de un tercio mas peque��a que la precedente [Icochilus extensus], de la que se distingue por la conformaci��n de la cara externa de los premolares y molares superiores, que es bastante diferente. Los premolares 2 , 3 y 4 , presentan las dos aristas perpendiculares de la parte anterior de la cara externa, mas estrechas, y de tama��o igual, sin que la segunda tome la forma de una columna saliente como en la especie anterior; adem��s la parte posterior externa de cada uno de estos dientes en vez de ser plana como en los del I. extensus es excavada por un surco perpendicular que viene inmediatamente detr��s de la segunda arista, como sucede con los verdaderos molares de la especie mencionada. Los verdaderos molares superiores del I. excavatus tienen las dos aristas perpendiculares de la parte anterior de la cara externa, casi confundidas en una sola, que toma el aspecto de una columna ancha en la que apenas se v�� un peque��o vestigio de la ranura que en los premolares y en los molares de la otra especie la dividen en dos aristas. Detr��s de esta columna, sobre la parte media de la cara externa, viene el surco perpendicular, mas estrecho y mas profundo que en los de la otra especie. Las muelas forman una s��rie dentaria mas arqueada, pero mas corta, pues las siete muelas superiores juntas solo ocupan un espacio longitudinal en l��nea recta de 22 mil��metros. La mand��bula inferior se distingue por un tama��o un poco menor, por la parte sinfisaria mas comprimida transversalmente, por el diastema entre el canino y el premolar todav��a bastante mas corto, y por los dos prismas que componen cada muela que son mas el��pticos y de consiguiente menos prism��ticos y menos oblicuos que en la otra especie ���. English translation. This species was a third smaller in size than the previous one [Icochilus extensus], and it is distinguished from it by some characteristics of the external face of upper premolars and molars. P2���4 present the two antero-external perpendicular edges narrower and equal in size, the second edge that does not acquire the form of a projecting column as in the previous species; in addition, the postero-external region of each of these teeth, instead of being flat as in those of Ic. extensus, is excavated by a perpendicular groove that appears immediately behind the second edge, as it happens with the true molars of the previous species. M1���3 of Ic. excavatus have the two perpendicular edges of the anterior part of the external face almost confused in a single one, which takes on the appearance of a broad column in which barely a small vestige of a groove is visible, in the premolars and molars of the other species this is a groove that divides the column into two edges. A perpendicular depression appears behind this column, on the middle part of the external face of the tooth, and it is narrower and deeper than in the other species. The cheek tooth series is arranged in a more arched position, but it is shorter because the space occupied, in straight line, by the seven upper molars is only 22 millimetres. The mandible is distinguished by a quite smaller size, by its symphyseal region being more transversally compressed, by the diastema between the canine and the premolar that is still quite shorter, and by the two prisms that constitute each tooth which are more elliptical and, consequently, less prismatic and less oblique than in the other species. Comments. Ameghino (1889: 472���473, plate 15: figs. 10���13) described and illustrated this taxon based on different characteristics of the upper and lower cheek teeth. According to Ameghino���s catalogue and Mones (1986), MACN-A 177 to MACN-A 180 are the type material of the species. The mandibular symphysis MACN-A 177 and the fragmented mandible MACN-A 178 match the original figures 12 and 13, respectively (Ameghino 1889: plate 15), which are herein reproduced (Figs. 3 G���K). Fortunately, we could locate the right maxilla MACN-A 9681, which matches figure 11 of the Atlas (Ameghino 1889) herein reproduced in Figure 3 G. On the other hand, even though the fragmented maxilla MACN-A 179 (Fig. 6 F) and missing MACN-A 180, a mandibular or maxillary fragment according to the inventory, were not originally illustrated, they cannot be discarded as syntypes because both are part of the same lot as MACN-A 177 and MACN-A 178. Unfortunately, it was not possible to find an m3 that matches the figure 10 of the Atlas (Ameghino 1889: plate 15), but it is also considered as part of the type series of the species. Consequently, MACN- A 177 to MACN-A 180 and MACN-A 9681 are the syntypes of Ic. excavatus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 205-206, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Interatherium anguliferum Ameghino, 1894a Holotype. MACN-A 3444 (Fig. 1 C), a fragmented right maxilla with C and P2���M1 series. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� De taille interm��diaire entre celle de 1��� I. rodens et celle de 1��� I. supernum dont elle se distingue par l'absence de la premi��re pr��molaire sup��rieure. La canine sup��rieure est bien d��velopp��e et isol��e par des diast��mesen avant et en arri��re. Les p. 2 �� 4 ont les deux ar��tes perpendiculaires de l'angle ant��rieur externe tr��s fortes. Longueur du bord ant��rieur de la canine au bord post��rieur de la premi��re vraie molaire sup��rieure, 17 mm ���. English translation. Size intermediate between I. rodens and I. supernum, from which it is distinguished by the absence of the first upper premolar. The upper canine is well developed and anteriorly and posteriorly isolated by diastemata. P2���4 have the two perpendicular columns of the antero-external angle very strong. Length from the anterior region of the upper canine to the posterior border of the first true upper molar, 17 mm. Comments. Ameghino (1894a) did not illustrate any specimen of this species. According to Ameghino���s catalogue and Mones (1986), the maxilla MACN-A 3444 is the type specimen of the species. This material matches the original description provided by Ameghino (1894a) because its dP1 is absent, there are diastemata anterior and posterior to C, and the series C���M1 is 17.3 mm long. Therefore, MACN-A 3444 is confirmed as the holotype of I. anguliferum., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 201, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus undulatus Ameghino, 1889 Holotype. MACN-A 373 (Fig. 3 L), an incomplete left maxilla with P3���M3. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1889: 473). ��� Esta especie era de talla intermediaria entre las dos precedentes [Icochilus extensus and Icochilus excavatus], de las que se distingue por los molares y premolares superiores de una conformaci��n bastante distinta, particularmente sobre la cara externa. Los premolares superiores tienen las dos aristas perpendiculares de la parte anterior de la cara externa un poco mas anchas, pero mas bajas, sin levantarse sobre el plano de la cara externa como sucede con las dos especies precedentes, separadas por una ranura poco profunda, y la segunda arista seguida hacia atr��s de una ranura id��ntica �� la precedente, de donde resulta que la cara externa de estos dientes presentan tres elevaciones perpendiculares poco elevadas, separadas por dos surcos poco profundos, que dan �� la superficie externa de la muela un aspecto ligeramente ondulado, muy diferente del que caracteriza los mismos dientes del I. extensus y el I. excavatus. Los verdaderos molares difieren todav��a mas que los premolares, pues las dos aristas externas anteriores est��n completamente confundidas en una sola columna convexa bastante ancha; cada muela superior presenta as�� sobre el lado externo dos columnas �� l��bulos perpendiculares poco salientes que corresponden �� los dos l��bulos internos, estando separados por una peque��a depresi��n perpendicular poco profunda, opuesta al pliegue y profundo surco perpendicular del lado interno. Las ��ltimas muelas superiores, y sobre todo el ��ltimo verdadero molar, se distingue por una corona muy comprimida. La serie dentaria era casi recta ���. English translation. Intermediate in size between the two previous species (Icochilus extensus and Icochilus excavatus), from which it is distinguished by presenting upper premolars and molars with a quite different conformation, particularly on the external face. Upper premolars have the two antero-external perpendicular edges separated by a shallow groove, which are a little wider, but lower, without rising above the plane of the external face, as it happens in the two preceding species; behind the second edge there is an identical depression to that of the preceding one, leading to the external face of these teeth have three slightly elevated perpendicular elevations, separated by two shallow sulci; as a result, the external surface of the premolars is slightly undulated, what markedly differs from Ic. extensus and Ic. excavatus. True molars differ even more than the premolars as the two antero-external edges are completely confused in a single, very wide and convex column; thus, each upper molar has two perpendicular columns or lobes on the external side, which are not very prominent and correspond to the two internal lobes, being separated from each other by a small and shallow perpendicular depression, opposite to the fold and the deep perpendicular groove of the inner side. The last upper molars, particularly M3, are distinguished by a very compressed crown. The dental series was almost straight. Comments. Ameghino (1889: 473) founded this species based on a maxillary fragment illustrated in his Atlas (Ameghino 1889, plate 15: fig. 14). According to Ameghino���s catalogue and Mones (1986), the incomplete maxilla MACN-A 373 is the type specimen of the species. This material matches the original diagnosis and illustration provided by Ameghino (1889, plate 15: fig. 14), herein reproduced (Fig. 3 M), and it is confirmed as the holotype of Ic. undulatus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 206-208, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

Icochilus Ameghino, 1889 Type species (this contribution). Icochilus extensus Ameghino, 1889: 471 ���472. Comments. Ameghino (1889) did not designate the type species of genus Icochilus among the four species originally defined within this taxon. Neither Sinclair (1909), who was the first reviewer, nor Mones (1986) noticed this omission. As a result, this nomenclatural act was pending until now, because for genera described before 1930, the reviewer must select the type species among those included within the genus when it was described (ICZN 2000: Art. 69). In this case, Ameghino (1889) defined Ic. extensus, Ic. excavatus, Ic. undulatus and Ic. rotundatus along with the generic description. As there is no priority criterion regarding the pages, the priority is determined by the reviewer (ICZN 2000: Art. 69). Therefore, we choose Ic. extensus as the type species, because its type material involves an almost complete individual with reliable and recognizable dental and craneo-mandibular features. In addition, the original diagnosis of the genus was based on this species due to its completeness, and was used by Ameghino as a reference for describing the remaining three., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 202-203, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i-xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625.","ICZN (2000) Codigo internacional de nomenclatura zoologica. 4 th edition, CSIC-MNCN Madrid, Caja Espana, The International Comission on Zoological Nomenclature and Sociedad de Amigos del MNCN (eds), Madrid, 156 pp."]}

Icochilus anomalus Ameghino, 1894a Holotype. MACN-A 3634 (Fig. 5 I), mandibular right fragment with c and p2���3, currently missing. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 16). ��� De la m��me taille que l��� Icochilus extensus. Cette esp��ce se distingue facilement par l'atrophie et la disparition de plusieurs dents. L'incisive inf��rieure externe est tr��s petite. La canine inf��rieure est extr��mement petite, et isol��e en avant et en arri��re par des diast��mes assez longs, tandis que dans presque toutes les autres esp��ces du m��me genre cette dent est au contraire bien d��velopp��e et couch��e en avant sur les incisives, dont elle en a la forme. La premi��re pr��molaire inf��rieure a compl��tement disparu. La deuxi��me pr��molaire inf��rieure est bien d��velopp��e et avec deux sillons perpendiculaires oppos��s, l'un interne et l'autre externe ���. English translation. With the same size as Icochilus extensus. This species is easily distinguished by the atrophy and disappearance of several teeth. The external lower incisor is very small. The lower canine is extremely small and is anteriorly and posteriorly isolated by rather long diastemata, whereas in almost all the other species of the genus this tooth is instead, well developed and leaned on the incisors. The first lower premolar is absent. The second lower premolar is well developed and exhibits two opposite, internal and external, perpendicular grooves. Comments. Ameghino (1894a) described this species, but did not illustrate any specimen of it. Ameghino���s catalogue and Mones (1986) indicate the mandibular fragment MACN-A 3634 as the type specimen of the species. This is the only material assigned to this species in Ameghino���s catalogue, but unfortunately, it could not be found in the Ameghino Collection. Nevertheless, when studying Scott���s photographic catalogue published by Vizca��no et al. (2017), it was possible to identify the photograph No. 309 (Fig. 5 I) as the fragmented mandible assigned to Ic. anomalus by Ameghino (1894a). That specimen matches the original description, because it exhibits a reduced lower canine, diastemata anterior and posterior to this tooth, and the absence of dp1. Taking into consideration that MACN-A 3634 was the only specimen assigned to this species, it is highly probable that the photograph No. 309 corresponds to the currently missing specimen. Therefore, if this was the case, it should be considered the holotype of Ic. anomalus, but unfortunately it has not been located., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 211-212, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625.","Vizcaino, S. F., de Iuliis, G., Brinkman, P. D., Kay, R. F. & Brinkman, D. L. (2017) On an album of photographs recording fossils in the \" Old Collections \" of the Museo de la Plata and Ameghino's private Collection at the beginning of the XXth century \". Publicacion Electronica de la Asociacion Paleontologica Argentina, 17, 14 - 24. https: // doi. org / 10.5710 / PEAPA. 21.06.2017.244"]}

Icochilus curtus Ameghino, 1894a Holotype. Not located, probably lost. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 17). ��� De la m��me taille que l��� I. extensus. Cette esp��ce se distingue facilement par le grand raccourcissement de la derni��re molaire inf��rieure qui est �� peine un peu plus longue que l'avant-derni��re, et par son lobe post��rieur qui est convexe sur le c��t�� externe, sans vestige du sillon perpendiculaire qu'on voit sur la m��me dent des autres esp��ces. La derni��re molaire inf��rieure a pr��s de 5 mm. de longueur, et les deux derni��res molaires occupent un espace de 9 mm. de long ���. English translation. With the same size as Ic. extensus. This species is easily distinguished by the great shortening of the last lower molar, which is just a little longer than m2, and by its posterior lobe that is convex on the external side and it does not exhibit the perpendicular groove seen on the same tooth in the other species. The last lower molar is nearly 5 mm long, and the last two molars occupy a space of 9 mm. Comments. Ameghino (1894a) did not illustrate this species. According to Ameghino���s catalogue and Mones (1986), the mandibular fragment MACN-A 9852 is the type material of the species. However, MACN-A 9852 does not match the original description, because its m3 exhibits a labial groove in the talonid as in other species of Icochilus. Among the remaining specimens assigned to this species within the Ameghino Collection, other two fragmented mandibles, MACN-A 9853 and MACN-A 9854, neither present the diagnostic characteristics described for the m3. In addition, no material labelled as Icochilus sp., Interatherium sp., Icochilini, Icochilinae and Interatheriidae indet. matches the original description provided by Ameghino (1894a). As a result, the type specimen of Ic. curtus has not been located., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 215, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}

The first known Interatheriinae (Interatheriidae, Notoungulata) were described by Florentino Ameghino based on fossils collected by his brother Carlos in diverse Argentinean early Miocene outcrops in the Santa Cruz Province, which are housed at different institutions. In order to perform a systematic study of the subfamily, it is essential to revise as much specimens as possible, but first of all the type material of the species under study. Due to the fact that Florentino Ameghino never referred to any type specimens with a collection number in any of his publications, their identification becomes a complex task. In consequence, when studying the species erected by Ameghino within the genera Interatherium and Icochilus, we identified a lack of correspondence between some materials catalogued as type specimens and the original descriptions. In this contribution, we present the type specimens of 18 out of the 21 Santacrucian species of Interatherium (4) and Icochilus (14) within the paleontological collection of the Museo de La Plata and Ameghino National Collection at the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”. Four case studies are presented: a) specimens correctly identified; b) materials erroneously catalogued as type specimens; c) specimens catalogued as type, whose status cannot be evaluated because they are lost; and d) specimens not catalogued as types, but herein recognised as such. As the selection of the type species of Icochilus was pending, Ic. extensus is herein designated as such. The lectotypes of Ic. extensus and Ic. multidentatus are selected among their identified syntypes.

In this work, there were analyzed dental remains of a Toxodon sp. (Mammalia, Notoungulata) specimen rescued from the riverbank of the Ypane River in Paraguay. Several techniques were used to analyze the different geological aspects of the samples, thus providing keys to the understanding of fossilization processes and the implications of paleoenvironmental conditions in the apatites present in the dental remains. The identification of the chemical substances present in the sample was made by Raman and Fourier Transform Infrared (FTIR) spectroscopy, the chemical composition of the samples was determined using energy dispersive X-ray fluorescence (EDXRF) and X-ray photoelectron spectroscopy (XPS), and the mineralogy by X-ray Diffraction (XRD). It is worth mentioning that this work is the first in the area of Paleometry carried out in Paraguay.

Members of the Order Notoungulata are among the most diverse and common mammals in South America during the Cenozoic. Several lineages within notoungulates (e.g., suborders Typotheria and Toxodontia) show a tendency for increased body sizes and hypsodonty during the last 50 Myr. However, the timing, evolutionary mode, and drivers of such tendencies are not entirely understood. In this paper, we use an extensive database of notoungulate fossil occurrences and body mass and hypsodonty estimates to characterize the evolutionary mode of these two phenotypic traits over time, test the extent to which several factors (e.g., development of open environments in the south of South America) have influenced it through time, and investigate whether large trait values were selected through elevated origination or reduced extinction rates. Our results demonstrate that most of the major notoungulate clades evolved toward larger body sizes (up 1500 kg) and higher tooth crown, from a small and low-crowned tooth ancestor, in a punctuated mode. We also show that body mass and the hypsodonty in typotherians and toxodonts had a coupled evolutionary history. Species sorting was a relevant macroevolutionary process in some notoungulate clades, as taxa with high teeth crown and body mass had lower extinction rates. Finally, the development of the hypsodonty in notoungulates must reflect repeated and quick instances of adaptive responses to the increased availability of volcanic or other terrigenous particles, within the broad context of the SSA Cenozoic Andean mountain building.

Hegetotheriidae is one of the most advanced clades within the endemic South American placental Order Notoungulata. The species Hegetotheriopsis sulcatus Kramarz & Paz, 2013 Kramarz, A. & Paz, E. R. 2013. Un Hegetotheriidae (Mammalia, Notoungulata) basal del Mioceno temprano de Patagonia. Revista Mexicana de Ciencias Geológicas, 30, 186–195. [Web of Science ®], [Google Scholar] differs from all other known hegetotheriids in having a peculiar combination of cranial and dental features, some of them shared with Archaeohyracidae (sister group of Hegetotheriidae). A previous cladistic analysis supported H. sulcatus as the earliest diverging hegetotheriid. Nevertheless, a more recent analysis, based on a different data matrix, concluded that this species is an advanced form within the family, with the little-known Prohegetotherium sculptum Ameghino, 1897 Ameghino, F. 1897. Les mammifères crétacés de l'Argentine. Deuxième contribution à la connaissance de la faune mammalogique des couches à Pyrotherium. Boletín del Instituto Geográfico Argentino, 18, 406–521. [Google Scholar] (late Oligocene) being the most basal taxon. Here we present a revision of the concept and the content of P. sculptum based on a re-examination of the type specimens. We find that this material exhibits several dental and cranial characters not recognized in all previous studies; we conclude that no specimen other than the types can be assigned to P. sculptum, and that all the synonymies previously proposed (i.e. P. shumwayi and P. crassus) are unfounded. A new cladistic analysis, combining characters from the two aforementioned analyses, confirms the position of H. sulcatus as the earliest diverging hegetotheriid. The taxon was originally described based on remains from early Miocene deposits in central and northern Patagonia (Sarmiento, Chichinales and Cerro Bandera formations). Here we report new material from the late Oligocene of Cabeza Blanca (central Patagonia), and reassign other material previously attributed to Prohegetotherium from presumably equivalent levels at Quebrada Fiera (central West Argentina). These remains extend the occurrence of H. sulcatus back to the late Oligocene, and fill an important gap of the early record of Hegetotheriidae. Fil: Kramarz, Alejandro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Bond, Mariano. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The Paleogene vertebrate-bearing sites of Brazil are restricted to few formations such as Maria Farinha (Late Cretaceous-early Paleocene), Itaborai (early Eocene), Entre-Corregos (Eocene-Oligocene), and Tremembe (late Oligocene-early Miocene). A new Paleogene fauna is reported from an outcrop of the Guabirotuba Formation located at Curitiba, Parana State, southern Brazil. The Guabirotuba Formation is a stratigraphic unit of the Curitiba Basin, which belongs to the Cenozoic continental rift system of southeastern Brazil, a predominantly half-graben and horst system. The sedimentary facies indicate a fluvial distributary depositional system associated with floodplain, generated under humid climate conditions alternating with drier periods. This new Paleogene fauna, here named the Guabirotuba Fauna, has invertebrate and vertebrate taxa, including mammals (Cingulata, Notoungulata, Astrapotheria, and Metatheria). The fossil remains of seven armored xenarthrans are identified, including the description of a new species and genus named Proeocoleophorus carlinii. The Guabirotuba ungulates are assigned to Interatheriidae, Oldfieldthomasiidae, and Astrapotheria. The metatherian mammals are represented by a sparassodont, a palaeothentoid, and an argyrolagoid. This new mammalian fauna preliminarily suggests a late middle Eocene age (Barrancan South American Land Mammal Age) for the Guabirotuba Formation.

Thomas H. Huxley (1870) mentioned as Homalodotherium some fossils sent to him by Dr. Robert O. Cunningham, and sent these remains to William H. Flower to be described. Flower presented at the same time at the Royal Society of London (reception May 30, and presentation June 19, 1873) a short abstract (Flower, 1873) and a full description (Flower, 1874), which were, however, published with different date, being the abstract previous to the complete work. This fact gave place to subsequent nomenclatural changes because the author used a different generic name in the paper published in 1874, Homalodontotherium instead of Homalodotherium. Besides, Flower’s complete work is often referred to 1873 due to the date of presentation, but it was published in 1874. The abstract included a general comparison of the fossil, and the taxonomic name Homalodotherium cunninghami appears in the title. Fil: Seoane, Federico Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos ; Argentina Fil: Hernández del Pino, Santiago Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Scioscia, Cristina Luisa. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Cerdeño Serrano, Maria Esperanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

In this contribution, we report the discovery of Archaeogaia macachaae gen. et sp. nov., one of the oldest notoungulate recovered from the upper section of Mealla Formation in the Tonco Valley (Northwestern Argentina, Salta Province). The new material consists on a left mandibular fragment with damaged m1 and complete m2-3. Archaeogaia macachaae is characterized by the following combination of features: m1 slightly shorter than m2 and both larger than m3; brachydont molars; talonid mesio-distally shorter than trigonid; metaconid slightly taller than protoconid and distally placed; reduced paraconid in m2; metalophid straight in m2–3, but it runs mesially forming a slightly obtuse angle in the labial edge in m2, whereas it is more transverse in m3; transverse entolophid; mesial cingulid extending from the middle to the lingual face of molars; and distal cingulid connecting the hypoconulid with the mesial face of the entoconid on m2–3. We perform a phylogenetic analysis based on a data matrix composed of 147 craniodental characters and 70 taxa. The analysis yields 6104 most parsimonious trees of 423 steps each. In the strict consensus previously well-supported clades collapse into a polytomy; and Archaeogaia is positioned within the order Notoungulata based on two synapomorphies: a) presence of a transverse entolophid, and b) lower cheek teeth with short mesio-distal protolophid, transverse metalophid and mesio-distal hypolophid slightly convex labially. The former character was recovered as a synapomorphy for Notoungulata in several previous studies. According to the reduced consensus, Archaeogaia occupies different positions within the order; these fluctuating locations could be the result of the presence of plesiomorphic features in the holotype, and the absence of the structures that define the notoungulate clades in which the new taxon is located. The paleomagnetic data indicates that the Mealla Formation was deposited during Chron 27r to the base of Chron 26r (latest Danian-earliest Selandian). In this context, we discuss the finding of Archaeogaia, and the age of Mealla Formation in the South American biochronology.