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Pelecanus paranensis sp. nov., a new pelican (Aves, Pelecanidae) from the marine Upper Miocene Paraná Formation, which crops out in the Province of Entre Ríos, Argentina, is described. This record constitutes the first report of a fossil pelican from Argentina and the southernmost from South America. The holotypical specimen consists of a very large and nearly complete pelvis, which is characterized by having the cristae iliacae dorsales continuous throughout its entire length and a large foramen acetabuli. The U-shaped morphology of the postacetabular section of the pelvis of the new species as well as the wide incisura sutura iliosynsacralis, allow to infer its phylogenetic position within the New World pelican species clade, showing a close relationship with the clade (P. occidentalis + P. thagus). A probable trans-Atlantic dispersal route for the ancestor of the New World pelicans is thus inferred. The inland Paranaense Sea, which flooded the South American Chaco-Paraná basin during the mid-Neogene, is proposed as a south-north pathway for ancestral forms of the clade (P. occidentalis + P. thagus). These regressive marine paleoenvironments of the Late Miocene may have acted as the evolutionary driver for the transition of pelican species from brackish or freshwater habitats to those inhabiting strictly marine coastlines.

A major barrier to advancing ornithology is the systemic exclusion of professionals from the Global South. A recent special feature, Advances in Neotropical Ornithology, and a shortfalls analysis therein, unintentionally followed a long-standing pattern of highlighting individuals, knowledge, and views from the Global North, while largely omitting the perspectives of people based within the Neotropics. Here, we review current strengths and opportunities in the practice of Neotropical ornithology. Further, we discuss problems with assessing the state of Neotropical ornithology through a northern lens, including discovery narratives, incomplete (and biased) understanding of history and advances, and the promotion of agendas that, while currently popular in the north, may not fit the needs and realities of Neotropical research. We argue that future advances in Neotropical ornithology will critically depend on identifying and addressing the systemic barriers that hold back ornithologists who live and work in the Neotropics: unreliable and limited funding, exclusion from international research leadership, restricted dissemination of knowledge (e.g., through language hegemony and citation bias), and logistical barriers. Moving forward, we must examine and acknowledge the colonial roots of our discipline, and explicitly promote anti-colonial agendas for research, training, and conservation. We invite our colleagues within and beyond the Neotropics to join us in creating new models of governance that establish research priorities with vigorous participation of ornithologists and communities within the Neotropical region. To include a diversity of perspectives, we must systemically address discrimination and bias rooted in the socioeconomic class system, anti-Blackness, anti-Brownness, anti-Indigeneity, misogyny, homophobia, tokenism, and ableism. Instead of seeking individual excellence and rewarding top-down leadership, institutions in the North and South can promote collective leadership. In adopting these approaches, we, ornithologists, will join a community of researchers across academia building new paradigms that can reconcile our relationships and transform science. Spanish and Portuguese translations are available in the Supplementary Material.

We describe a new extinct spiny rat,Proclinodontomys dondasin. gen. n. sp. (Rodentia, Caviomorpha, Echimyidae), represented by a noteworthy preserved skull and mandible from the early-middle Pleistocene outcrops at the coastal cliffs of SE Buenos Aires Province (Central Argentina). Phylogenetic analyses allow us to propose that the new species described here and the already knownEurzygomatomys mordax(Winge) represent a new genus closely related to the livingEuryzygomatomys spinosusandClyomys laticeps. The new genus differs fromEuryzygomatomysandClyomysby having much more procumbent upper incisors, a more developed fossa for the M. temporalis, more flared and laterally expanded zygomatic arches, frontal less markedly expanded posteriorly, jugals much deeper anteriorly than posteriorly, with the dorsal border descending more abruptly posteriorly, smaller orbital cavity, and external auditory meatus relatively smaller and slanted upward and backward. Several features of the new species reflect a higher degree of adaptation to semifossorial habits than those ofE.spinosus. The origin of the semifossorial ecomorphotype within echimyids may have been triggered by the expansion of relatively open and arid environments that arose near the Miocene-Pliocene boundary. The record of this new echimyid in Central Argentina indicates that during the early-middle Pleistocene, the southern limit of the geographic range of extinct representatives of the Brazilian lineage of semifossorial echimyids extended farther south than that of their living members.UUID:http://zoobank.org/c30ec1fe-4352-4867-a02f-e0d45c884bfe

The first unequivocal records of teratornithid birds from the Pleistocene of South America are here described, adding a new member, and the largest, to this highly diversified guild of large carnivorous flying birds that lived during these times in the Americas. The new specimens come from four fossiliferous localities of Central Argentina that range in age from the late middle to the early late Pleistocene, and agree with other known Teratornithidae taxa in size and morphology. We updated the taxonomy of the family and analyzed its fossil record in the Pleistocene of both Americas. The available evidence suggests that forms related to Teratornis lived in the South American Pampas around the time of the Last Interglacial (MIS 5), but they were restricted to North America during the latest Pleistocene (late MIS 3–early MIS 1). The contrasting latest Pleistocene record of teratorns between North and South America is not easy to understand, especially because the supposed flight capacity of these birds did not prevent them from crossing large geographical barriers. Although a bias in the fossil record cannot be ruled out, it is possible that the teratorns were limited in South America by paleoclimatic–paleoecological factors as yet undetermined, and/or that the northern and southern Pleistocene species had very dissimilar specializations. In relation to the latter, the previous inferences on the teratorn paleobiology without phylogenetic support are preliminarily questioned here.

A large nearly complete specimen of a Crested Tinamou (Eudromia, Tinamidae, Aves) is described. It was collected at ‘Nicolás Vignogna III’ Quarry in Marcos Paz County (Buenos Aires Province, Argentina), coming from near the top of a succession assigned to the Lujanian Stage. Radiocarbon dates constrain the age of the fossil bearing lithosome to the late Pleistocene – early Holocene, including the complete geochronological interval assigned to MIS 2. The new fossil specimen of Eudromia from Marcos Paz exceeds the size range of living species of the genus; but it is osteologically almost indistinguishable from them. Based on the lack of conclusive morphological and metrical differences with modern Eudromia spp., its specific status is not definitely ascertained in this contribution, being considered as a probable large morph of E. elegans. Crested tinamous are inhabitants of open and xeric environments with warm temperate to cold temperate climatic conditions. The fossil location is more than 250 km east of the eastern distributional limit of the nearest extant species. This geographical outlier could be tentatively associated with the expansion of arid or semiarid paleoenvironments typical of the Central or Patagonian domains over the temperate Pampean grasslands during the MIS 2 times. Fil: Cenizo, Marcos. Universidad Maimónides; Argentina. Museo de Historia Natural de la Provincia de la Pampa; Argentina Fil: Noriega, Jorge Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Diederle, Juan Marcelo. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Soibelzon, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Paleontología; Argentina Fil: Soibelzon, Leopoldo Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Paleontología; Argentina Fil: Bouzo Rodríguez, Sergio. Facultad de Ciencias Naturales y Museo, Universidad Nacional de la Plata; Argentina Fil: Beilinson, Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina

Here we describe an unusual fossil assemblage found inside a crotovine from the late Pliocene Chapadmalal ‘Formation’ (Buenos Aires Province). This assemblage contains the greatest vertebrate diversity recovered inside an ichnofossil of this type, including skeletal remains of dasypodids, didelphids, procyonids, anurans and caviomorph rodents within coprolites and disaggregated scatological waste. We describe four general size types for crotovines and palaeoburrows found in the Pliocene to Holocene of Argentina and Brazil, of which the structure found corresponds to the ‘mid-large’ size type and is linked to the activity of the large dasypodid Ringueletia simpsoni. The scatological remains are assigned to a small-sized carnivorous mammal with a body mass of between 1 and 6 kg. Within the guild of Chapadmalalan omnivorous–carnivorous mammals, this inferred mass range is restricted to large didelphids and mid-sized procyonids (represented in the assemblage by Thylophorops chapadmalensis and Cyonasua...

The Antarctic pelagornithid record is restricted to few isolated remains from the Eocene of Seymour Island in the Antarctic Peninsula. Here we report the oldest Antarctic pseudo-toothed bird. It is represented by an incomplete humerus lacking its proximal end, which comes from the lower Eocene levels of the La Meseta Formation (Seymour Island). This new specimen facilitates a review of all known pelagornithids from this continent. Antarctic pelagornithids were classified into two morphotypes that exhibit a mix of putative plesiomorphic and derived characters. Considering the worldwide pelagornithid record and according to estimated wingspans, four approximate size-types were identified. The oldest Antarctic specimens (two fragmentary humeri, middle Ypresian) were assigned to morphotype 1 and correspond to the large size-type. The younger materials (Bartonian/?Priabonian) here assigned to morphotype 2 (some cranial remains, fragmentary tarsometatarsus and humerus) correspond to the giant size-type and represent one of the largest known pseudo-toothed birds. Even though species level phylogenetic affinities of Pelagornithidae remain poorly resolved, three key evolutionary events can be recognized: (1) the disappearance of Dasornis in the Early Eocene and the appearance of more advanced forms with a trend to the specialization of large soaring capacity, (2) the origin of Pelagornis sensu lato species in the early Oligocene, and (3) the appearance and dominance of a highly specialized terminal group at Mio/Pliocene time span. Fil: Cenizo, Marcos. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Acosta Hospitaleche, Carolina Ileana Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Reguero, Marcelo Alfredo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

In the present paper we report the most complete fossil avifauna from the southern cone of South America. The specimens here described were collected in the Paso Otero locality, at the middle stream of the Quequen Grande River, Pampean Region (Buenos Aires Province, Argentina). The fossiliferous levels belong to the La Chumbiada Member of Lujan Formation (37,800 ± 2300 yr BP, late Pleistocene). The assemblage is represented by 60 specimens belonging to at least 22 taxa. The radiocarbon age indicates that Paso Otero birds represent the oldest late Pleistocene avifauna known from the South American continent and the first coming from a clear interstadial event (MIS3). Available evidence indicates similar environmental conditions during the MIS3 interstadial in the Pampean Region of Argentina and the post-Last Glacial Maximum stadials in southeastern Brazil. The absence of significant extinction events in the latest Pleistocene–early Holocene avifaunas of Brazil and Argentina suggests that the main avifaunal composition along southeastern continental lowlands may not be affected by the cyclic retraction and extension of open environments. On the contrary, the fossil record of Peru and Ecuador demonstrates that a large number of taxa, including aquatic and predatory-scavenger birds, have gone extinct along Andean environments at the Pacific coast, and late Pleistocene climatic oscillations may have played a more dramatic impact in these avian communities.

Los acantilados litorales del area comprendida entre Punta Iglesias y Arroyo Los Cueros (Partidos de General Pueyrredon y Mar Chiquita, Provincia de Buenos Aires) albergan una serie de sitios de gran importancia paleontologica. Estas geoformas han brindado cuantiosas colecciones que integran el acervo de museos locales y nacionales, representando herramientas esenciales para comprender los procesos geologicos, biologicos y socio-culturales del pasado regional. Sin embargo, dicho area evidencia un estado critico de vulnerabilidad patrimonial como consecuencia del incremento sistematico de la erosion costera y las alteraciones antropicas sobre las geoformas locales. Estas circunstancias obligan la urgente implementacion de planes de manejo costero que consideren la relevancia del patrimonio local de acuerdo al marco de proteccion legal que rige sobre estos bienes. Asimismo, la existencia de caracteristicas propicias en las comunidades locales podria representar una oportunidad para abordar la problematica mediante la integracion participativa de los sectores directa o indirectamente afectados. Sugerimos a los organismos implicados, la elaboracion y articulacion conjunta de un “Plan de Manejo Integrado del Patrimonio” considerando las particularidades de cada sector a los fines de coaccionar medidas que garanticen el resguardo de los bienes en riesgo. Especialmente, consideramos necesario el establecimiento de un area protegida sobre el frente acantilado de Camet Norte (Partido de Mar Chiquita), donde existe un yacimiento de condiciones excepcionales dentro la region pampeana y bajo una grave situacion de deterioro continuo.

El “Irenense” es una unidad controvertida, tradicionalmente empleada para incluir vertebrados fósiles y sus sedimentos portadores del Neógeno Tardío—Plioceno en sentido amplio—en el sur de la provincia de Buenos Aires, Argentina. Si bien originalmente fue pensado como un candidato para ocupar un lugar intermedio entre las faunas del Montehermosense y Chapadmalalense, casi un siglo después de su descripción el “Irenense” es aún pobremente conocido. En base a trabajos de campo realizados por nuestro equipo durante los últimos 25 años en su área tipo, el río Quequén Salado, revisamos los aspectos básicos del “Irenense”. Describimos las principales localidades paleontológicas y las correlaciones sugeridas por los fósiles y sedimentos y también discutimos la cronología de los depósitos. Concluimos que el “Irenense” es una unidad compleja compuesta por al menos dos agregados fosilíferos. Un agregado más antiguo se encuentra en los sedimentos expuestos en localidades ubicadas río abajo de la boca del arroyo Indio Rico; un agregado más joven está contenido en los afloramientos aguas arriba del punto mencionado e incluye al clásico sitio de Cascada Grande. El agregado más antiguo incluye al angulado Macrochorobates sp., al cenoléstido Pliolestes tripotamicus, al tardígrado Proscelidodon cf. P. patrius y al roedor Xenodontomys ellipticus, elementos que sugieren su inclusión en el Piso/Edad Huayqueriense sensu lato. El agregado más joven está tipificado por varios taxones incluyendo los roedores Actenomys sp. y Eumysops laeviplicatus, el argirolágido Argyrolagus sp., el didélfido Hyperdidelphys inexpectata, el macrauquénido Promacrauchenia cf. P. chapadmalense y el cingulado Ringúeletia simpsoni, sugiriendo un Piso/Edad Montehermosense. The “Irenean” is a controversial unit traditionally employed to embrace fossil vertebrates and bearing-sediments of late Neogene—roughly Pliocene—age in southern Buenos Aires Province, Argentina. Although originally intended as an intermediate unit between Montehermosan and Chapadmalalan faunas, almost a century after its description, the “Irenenean” is still poorly known. Based on fieldwork by our team during the last 25 years in its type area, the Quequén Salado River, we revisit the basic aspects of the “Irenean”. We describe the main paleontological localities and the correlations suggested by fossils and sediments and also discuss the chronology of these deposits. We conclude that the “Irenean” is a complex unit composed of at least two fossilife rous assemblages. An older assemblage is found in sediments exposed in localities downstream of the mouth of Indio Rico; a younger assemblage is contained in outcrops upstream of the mentioned point and includes the classic site of Cascada Grande. The older assemblage includes the cingulate Macrochorobates sp., the caenolestid Pliolestes tripotamicus, the tardigrade Proscelidodon cf. P. patrius and the rodent Xenodontomys ellipticus, and points to a sensu lato Huayquerian Stage/Age. The younger assemblage is typified by several taxa, including the rodents Actenomys sp. and Eumysops laeviplicatus, the argyrolagid Argyrolagus sp., the didelphid Hyperdidelphys inexpectata, the macraucheniid Promacrauchenia cf. P. chapadmalense, and the cingulate Ringueletia simpsoni, suggesting a Montehermosan Stage/Age. Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina Fil: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina Fil: Voglino, Damián. Provincia de Buenos Aires. Museo de Ciencias Naturales "A. Scasso"; Argentina Fil: Cenizo, Marcos. Fundación de Historia Natural Félix de Azara; Argentina. Provincia de La Pampa. Museo de Historia Natural; Argentina

Antarctoboenus carlinii nov. gen. nov. sp. is a large-sized falconiform bird from the La Meseta Formation (Lower Eocene) at Seymour (Marambio) Island, West Antarctica. The holotypical tarsometatarsus was originally assigned to Falconidae and its affinities to Polyborinae were pointed out. Detailed osteological and comparative analyses of the Antarctic specimen allowed recognition of the new taxon as a member of stem group Falconidae, i.e. it is supposed to belong to the early radiation of the falconiform lineage. Antarctoboenus carlinii is distinguished from members of crown group Falconidae by having a very shallow sulcus extensorius, a large foramen vasculare distale, an undistinguishable tendinal attachment for the m. adductor digiti II, and short trochlea metatarsi II, among its main diagnostic characters. Purported phylogenetic relationships between A. carlinii and Polyborinae are based on plesiomorphic characters retained in the tarsometatarsus of the latter clade. Our conclusions reinforce the hypothesis about the Neotropical or Austral origin of Falconidae supported by previous molecular phylogenies., Facultad de Ciencias Naturales y Museo

In the present paper, the geomorphological and sedimentary characteristics of the continental sequences exposed on the coastal cliffs and surrounding areas of the Centinela del Mar locality are described and interpreted. Fourteen lithofacies are defined, their relation, geometry and structure are represented using transversal and longitudinal detailed profiles. In the basal and medium sector of the profile, facies of different degrees of transport and aqueous rework were recognized. In the superior sector, a succession of marine peri-coastal facies corresponding to the «Belgranense» transgression (=Fm. Pascua) were identified, ending the secuence with relictual eolic facies. The different historical interpretations are discussed, homologating the units referred previously with the ones proposed on this paper. These units are correlated with those defined in the allostratigrapic scheme proposed by other authors for the area covered between Playa San Carlos and Arroyo Chapadmalal. This allowed recognize for the area under study the presence of the Punta San Andrés and Arroyo Lobería Alloformations (basal-medium and superior sector, respectively). Between these two entities, a association of well defined progradant marine facies are found and named on this paper as Centinela del Mar Alloformation. Finally, the information gathered here (magnetostratigraphy, radiometric dating, stratigraphic correlations, etc) indicates, at least preliminarily, that the secuence of Centinela del Mar corresponds to the Ensenadense-Lujanense interval (Lower Pleistocene - Holocene).Son descriptas e interpretadas las características geomorfológicas y sedimentarias de las sucesiones continentales expuestas en los acantilados litorales y sectores aledaños de la localidad Centinela del Mar. Se definen catorce litofacies, cuyas relaciones, geometría y estructuras son representadas mediante perfiles transversales y longitudinales de detalle. En el sector basal y medio del perfil fueron reconocidas facies de distinto grado de transporte y retrabajo ácueo, en tanto, en el sector superior fue identificada una secuencia de facies marinas y perilitorales correspondientes a la transgresión «Belgranense» (=Fm. Pascua), culminando la sucesión facies eólicas relictuales. Las diferentes interpretaciones históricas son ampliamente discutidas, homologándose las unidades referidas previamente con las propuestas en este trabajo. Dichas unidades se correlacionan con aquellas definidas en el esquema aloestratigráfico propuesto para el área comprendida entre Playa San Carlos y Arroyo Chapadmalal. Esto permitió reconocer para el área bajo estudio la presencia de las Aloformaciones Punta San Andrés y Arroyo Lobería (sector basal-medio y cuspidal, respectivamente). Entre estas dos entidades, se intercala una asociación de facies marinas progradantes hacia ambientes perilitorales definidas y nominadas aquí como Aloformación Centinela del Mar. Finalmente, la información aquí reunida (magnetoestratigrafía, dataciones radio-métricas, correlaciones estratigráficas, etc.) permite indicar, al menos preliminarmente, que la sucesión de Centinela del Mar corresponde al intervalo Ensenadense-Lujanense (Pleistoceno Inferior-Holoceno).

New bird fossils from the Santa Cruz Formation (lower–middle Miocene), Santa Cruz Province, Patagonia, Argentina, are described. They represent an indeterminate species of the extinct anhingid Macranhinga and a new genus and species of basal Anatidae Ankonetta larriestrai. The record of the giant darter Macranhinga constitutes the southernmost record for the family, and expands the known stratigraphic range of the genus, previously restricted to the upper Miocene. Based on an analysis of the fossil anhingid record from South America, we hypothesize that giant darters disappeared from South America in the early Pliocene due to climatic deterioration, regression of marine and freshwater environments, the arrival of placental carnivorous mammals, and also probably by competition with phalacrocoracid cormorants. The new anatid Ankonetta is based on an incomplete but informative tarsometatarsus, with superficial similarities to extant Dendrocygna. A brief overview of several fossil ducks from the Patagonian Ce...

Zurita, A.E., Soibelzon, E., Scillato-Yane, G.J. & Cenizo, M., March, 2009. The earliest record of Neuryurus Ameghino (Mammalia, Glyptodontidae, Hoplophorinae). Alcheringa 33, 49–57. ISSN 0311-5518. Among the Pleistocene Cingulata (Glyptodontidae), Neuryurus Ameghino is poorly documented; the only well-characterized species being N. rudis (Gervais), limited to the Ensenadan Age/Stage (early-middle Pleistocene) of the Pampean region in Argentina. The genus is characterized by dorsal carapace osteoderms with uniformly punctate exposed surfaces giving them a rugose, almost spongy aspect; sutures between the osteoderms are loose. Outside Argentina, Neuryurus has been recorded in western Uruguay and southern Brazil. Until now, its temporal range was restricted to the Ensenadan-Lujanian (early Pleistocene–early Holocene). In this context, we present the earliest record of the genus from the San Andres Formation (Sanandresian Substage; late Pliocene), consisting of dorsal carapace osteoderms and caudal rings and...

ANA M. BAEZ,", CARLOS A. SCANFERLA,2 FEDERICO L. AGNOLIN,73 MARCOS CENIZO,3 and MARTIN DE LOS REYES3; 1Universidad de Buenos Aires and Museo Argentino de Ciencias Naturales "Bernardino Rivadavia," Angel Gallardo 470, 1405 Buenos Aires, Argentina, baez@gl.fcen.uba.ar; 2Laboratorio de Anatomia Comparada y Evoluci6n de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia," Angel Gallardo 470, 1405 Buenos Aires, Argentina; 3Fundaci6n de Historia Natural Felix de Azara, Departamento de Ciencias Naturales y Antropologia, Universidad Maim6nides, Valentin Virasoro 732, 1405 Buenos Aires, Argentina

The oldest known birds from the Cerro Azul Formation are described, including the oldest records for the genera Eudromia and Nothura (Tinamidae), Milvago (Falconidae), Pterocnemia (Rheidae) and an undetermined Tyrannidae. The first remains of Phorusrhacidae for this formation are reported and a specimen previously referred to the giant teratorn Argentavis magnificens is reassigned to this family. We outline and update the current knowledge of the groups studied herein. The palaeornithological record from the Cerro Azul Formation is congruent with palaeoenvironmental inferences previously drawn from mammalian assemblages recovered from this unit, which point to the existence of open environments, possibly xerophyllous shrubby steppes, perhaps with some trees. These records are the first indications of a typically Pampean bird fauna at the end of the late Miocene in central-southern Argentina. Fil: Cenizo, Marcos Martín. Universidad Nacional de La Pampa; Argentina Fil: Tambussi, Claudia Patricia. 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 Fil: Montalvo, Claudia Inés. Universidad Nacional de La Pampa; Argentina

The Glyptodontidae (Mammalia, Xenarthra) are one of the most common paleofaunistic elements in the South American megafauna. In this context, of the six genera most frequently recorded in the South American Pleistocene (Glyptodon, Neosclerocalyptus, Hoplophorus, Neuryurus, Panochthus and Doedicurus), at least four (Hoplophorus, Neuryurus, Panochthus and Doedicurus) present structures in their caudal armor that could have had defensive/offensive functions, in addition to a solid dorsal carapace and cephalic shield. In this article, we provide the first record and description of a series of highly modified osteoderms, located at the anterolateral region and over the cephalic notch of the dorsal carapace. These "spine"-like osteoderms were found in two of the largest Pleistocene glyptodonts: Glyptodon munizi (early-middle Pleistocene) and, G. reticulatus (late Pleistocene-early Holocene). We propose that they are structures for protection of the neck and abdomen, the most vulnerable body regions of these large armored animals, since they are not covered by the cephalic shield, carapace or caudal armor. Noteworthy, structures like those described herein are not known in glyptodonts recorded before the Great American Biotic Interchange (GABI), so it could be a reaction to the arrival of Smilodon and Arctotherium (Carnivora, Mammalia) the largest terrestrial carnivores that ever lived in South America., Facultad de Ciencias Naturales y Museo