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The stratigraphic section and mammalian fauna of the new Miocene vertebrate site of Torrijos (Toledo, Spain) are described, and their relationships with the known Miocene faunae and the stratigraphic and paleogeographic context of the central Tajo basin are discussed, particularly in the Madrid area. The Torrijos fossiliferous beds are attributed to the mammalian unit MN4b more likely than to early MN5; these are consequenthly correlated with the regressive, late Burdigalian of the chronostratigraphic scale. Noteworthy is the dominance of Hispanotherium in this assemblage; also the presence of Protragocerus and of a new giraffid, which contributes to the exciting problem concerning the evolution of this family in the Mediterranean province in the Aragonian mammal age (Lower Miocene). The Torrijos fauna can be either correlated with the lower Madrid beds (Puente de Toledo, Hidroeléctrica, Moratines), or very slightly older, and preceeds an unconformity -videly paraconformable in the Madrid area-, which may be correlated with the so called Neo-castillan phase (Neo-Castellana)., Se describe el nuevo yacimiento de vertebrados miocenos de Torrijos (Toledo), su estratigrafía y los fósiles de mamíferos que se han podido identificar, en el contexto de las formaciones y faunas miocenas de la cuenca media del Tajo, especialmente del área de Madrid, y de su historia geológica y paleogeográfica. Los estratos fosilíferos se sitúan en la unidad mastológica MN4 más probablemente que en la MN5; se correlacionan, pues con la fase final, regresiva, del Burdigaliense. Destaca el dominio de Hispanotherium en la fauna, así como la presencia de Protagocerus y de un nuevo jiráfido problemático que añade interés a la evolución de este grupo en el ámbito Mediterráneo durante el Aragoniense. La fauna parece corresponder a las formaciones inferiores de Madrid (Puente de Toledo, Hidroeléctrica, Moratines) o precederles muy ligeramente, y se sitúa por debajo de una discordancia, generalmente paraconforme en el área de Madrid, correlacionable con la llamada Neocastellana., Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The contemporary mammalian communities of South America were defined by the rise of the Isthmus of Panama and by the deep climatic oscillations during the Pleistocene. Gomphotheres are a conspicuous group of North American immigrant mammals that came to South America during the late Pliocene and did not survive the great megafauna extinction approximately twelve thousand years ago. The present study compiles updated data on the phylogeny, systematics and ecology of this group in South America. Both genera reached South America in two independent dispersal events, Cuvieronius spread across the Andean corridor, while Notiomastodon extent along the eastern route. Cuvieronius hyodon is geographically restricted to the Andean Region in Ecuador, Peru, Bolivia, and Chile. Notiomastodon platensis was recorded in Ecuador, Brazil, Uruguay, Paraguay, Chile, and Argentina, especially the Pampean Region.

The apparently regular and favourable climate that characterizes the Holocene as an interglacial period shows, however, important climatic instability well documented in the Northern Hemisphere. These fluctuations from colder to warmer or wetter to drier affected both biodiversity and human societies in the last 12,000 years, although the impact in Southern America is still poorly known. We are here investigating the biodiversity of small mammal faunas, more sensitive to climatic changes than large mammals, combining taphonomic and palaeoecological data in the Argentine Pampas to better understand the global nature and effect of these Holocene climatic fluctuations. This paper is pioneering applying in this region palaeoecological methodologies practised in European sites, such as the chorotype classification and biomes overlap analyses. The Pampean Region is an ecotone with a confluence of three climatic regions where any change in climatic conditions should be easily detected. Our results, based on the palaeoecological requirements of small mammals, do not indicate severe changes, and most of the sites show climatic stability except for one of them, in which a possible trend towards present conditions (temperate/humid) can be inferred., Ministerio de Ciencia e Innovación (MICINN), Consejo Superior de Investigaciones Científicas (CSIC), Universidad Complutense de Madrid/Banco de Santander, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Secretaría General de Ciencia y Tecnología, Universidad Nacional del Sur, Banco Santander, Ministerio de Ciencia, Innovacion y Universidades, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The intra-montane Guadix-Baza Basin is one of the few continental basins in Europe that hosts a well-dated set of fossiliferous sites spanning from the latest Miocene to the late Middle Pleistocene. The Cúllar de Baza 1 (CB-1) represents a key site to investigate the effects of the Early-Middle Pleistocene Transition, considered a fundamental transformation in the Earth’s climate state. Our review and update of the large mammal assemblage, and particularly equids, is of paramount relevance to understand the systematic affinities and the evolution of the Early and Middle Pleistocene European horses. We confirm the occurrence of two different taxa, the medium sized Equus altidens and the larger E. suessenbornensis. Moreover, we illustrate that CB-1 is essential for the biochronological studies of the latest Early Pleistocene/Middle Pleistocene transition (Epivillafranchian/Galerian ELMA); in particular with regard to the Last Occurrences of the Etruscan rhino Stephanorhinus etruscus and the large deer Megaloceros savini and the First Occurrence of the water-rat Arvicola mosbachensis in the Iberian peninsula. Finally, a development of a mosaic environment characterised the CB-1 site contrasting with the conditions reported for other Iberian late Early and Middle Pleistocene localities.

The apparently regular and favourable climate that characterizes the Holocene as an interglacial period shows, however, important climatic instability well documented in the Northern Hemisphere. These fluctuations from colder to warmer or wetter to drier affected both biodiversity and human societies in the last 12,000 years, although the impact in Southern America is still poorly known. We are here investigating the biodiversity of small mammal faunas, more sensitive to climatic changes than large mammals, combining taphonomic and palaeoecological data in the Argentine Pampas to better understand the global nature and effect of these Holocene climatic fluctuations. This paper is pioneering applying in this region palaeoecological methodologies practised in European sites, such as the chorotype classification and biomes overlap analyses. The Pampean Region is an ecotone with a confluence of three climatic regions where any change in climatic conditions should be easily detected. Our results, based on the palaeoecological requirements of small mammals, do not indicate severe changes, and most of the sites show climatic stability except for one of them, in which a possible trend towards present conditions (temperate/humid) can be inferred.

The Salto de Piedra Paleontological Locality is located in the upper basin of the Tapalqué Creek (Buenos Aires Province, Argentine Pampas). Stratigraphic, sedimentological, and pedological studies were carried out in two exposed sections of the stream bank, corresponding to the late Quaternary (early/middle Pleistocene to Holocene). Six depositional units (allounits) were recognized, separated by discontinuities. These discontinuities correspond to both erosive discordances indicating fluvial reactivation and pedological horizons indicating stability intervals; among the latter, the development of a thick calcrete stands out. The facies and lithofacies identified in the depositional units correspond to sedimentation sub- environments having different attributes with respect to the preservation of the fossil record. This consists mainly of bone remains of mammals and snails of freshwater gastropods. The main vertebrate fossil- bearing units in Salto de Piedra correspond to channel facies and secondly to swampy floodplain facies, in accordance with taphonomic expectations. The stratigraphy shows changes in fluvial dynamics during the last glacial- integlacial cycles in the upper basin of the Tapalqué Creek and constitutes a good frame of reference for the paleontological, chronological and paleoenvironmental studies that are being carried out in this locality.

Rancho La Brea (California, USA) is the most emblematic Quaternary fossiliferous locality in the world, since both the high number and diversity of the specimens recovered and their excellent preservational quality. In the last decades, paleobiological and paleoecological knowledge of the different groups of mammals from this site has increased notably; however, some aspects have not yet been inquired or there is little information. In this work we provide information on one of the most abundant mammals of this site, the equid Equus occidentalis, based on the study, from osteohistological and histotaphonomic perspectives, of thin sections of different limb bones. On the one hand, from an osteohistological view- point, we observe that the distribution and characterization of bone tissues in the different skeletal elements are, in general lines, similar to that mentioned for other extant and extinct equids. Cyclical growth marks allowed us to propose preliminary skeletochronological interpretations. On the other hand, from a taphonomic viewpoint, we note that all the samples reflect an excellent preservation of the bone microstructure, slightly altered by different pre- and post-burial processes. The variations recorded evidence different taphonomic history and preservation conditions among pits. This is the first study including fossil material from Rancho La Brea exclusively based on the analysis of the bone microstructure features.

Proboscideans were keystone Cenozoic megaherbivores and present a highly relevant case study to frame the timing and magnitude of recent megafauna extinctions against long-term macroevolutionary patterns. By surveying the entire proboscidean fossil history using model-based approaches, we show that the dramatic Miocene explosion of proboscidean functional diversity was triggered by their biogeographical expansion beyond Africa. Ecomorphological innovations drove niche differentia- tion; communities that accommodated several disparate proboscidean species in sympatry became commonplace. The first burst of extinctions took place in the late Miocene, approximately 7 million years ago (Ma). Importantly, this and subsequent extinction trends showed high ecomorphological selectivity and went hand in hand with palaeoclimate dynamics. The global extirpation of proboscideans began escalating from 3 Ma with further extinctions in Eurasia and then a dramatic increase in African extinctions at 2.4 Ma. Overhunting by humans may have served as a final double jeopardy in the late Pleistocene after climate-triggered extinction trends that began long before hominins evolved suitable hunting capabilities.

The Pampean Region contains sedimentary sequences with abundant mammal fossil records, which constitute the chronological outline of the Plio–Pleistocene of South America. These classic localities have been used for more than a century to correlate with other South American regions. Throughout this time, a series of misinterpretations have appeared. To understand the stratigraphic significance of these localities and the geochronological situation of each unit referring to the Pleistocene, a critical historical study of the antecedents was carried out, evaluating the state of each unit. The biostratigraphic studies of the Pampean Region’s mammalian faunas improved the understanding of biogeographic changes taking into account the environmental fluctuations of the Pleistocene.

The Gomphotheriidae family belongs to the Proboscidea order. Gomphotheres were elephant-like mammals whose representatives inhabited North America from the Middle Miocene to the late Pleistocene. In this work, a gomphothere remains from Santiago Tepeticpac (Tlaxcala, Mexico) are described. The comparative study with other Proboscidea, mainly from different localities of Mexico and South America, mostly Argentina and Brazil, allowed to identify them as Cuvieronius genus. The microwear signature together with carbon and oxygen stable isotopes showed that this animal was a mixer feeder and inhabited open zones with patches of wooded flora. These analyses also indicated the presence of high abrasiveness components and C4 plants (grasslands) and medium to low wearing elements as well as C3 vegetation (forest) in the site. The strontium isotopic signature implies that this gomphothere lived in the Puebla-Tlaxcala Valley. The paleoenvironmental inferences would show regional conditions.

Based on data from analyses on previously-reported carbon stable isotope data from dental enamel and dentine from tusks reported in the literature, diets were inferred for the gomphothere genera Amebelodon, Cuvieronius, Gomphotherium, Rhynchotherium, Serbelodon, and Stegomastodon (Proboscidea, Gomphotheriidae) that inhabited the Americas during the Cenozoic. Amebelodon, Gomphotherium, and Serbelodon specimens of the Barstovian and Clarendonian faunal stages fed on C plants; while the same Hemphillian genera consumed a mixed C/C diet. Hemphillian Rhynchotherium were mixed-diet feeders while Blancan specimens of the same genus fed on C plants. Stegomastodon from the same Blancan period consumed a mixed C/C diet, similar to Rancholabrean animals, although Lujanian specimens ate C plants. As for the genus Cuvieronius, Irvingtonian, Rancholabrean, and Lujanian specimens consumed a mixed C/C diet. These results suggested that American gomphotheres displayed generalist feeding habits, allowing them to inhabit different environments in extensive areas of the continents, and survive to the end of the Pleistocene.

A comparative study was made with the known record of equids species in South America, identifying the remains as Equus neogeus, Hippidion devillei, and Hippidion principale. These data increase the record of Equidae in South America and provide new evidence about the chronological and geographical distribution. The sedimentary deposits of the Lujan Formation outcropping at Tapalqué creek (4 to 120 ky) were accumulated through fluvial processes. This Formation comprises a rich vertebrate fauna corresponding to the Lujanian South American Land Mammal Age, which includes numerous and diverse vertebrate remains. The taphonomic analysis indicates that the faunistic assemblage was formed and was subject to diagenetic processes without distinction of its action in the fossiliferous levels, that can be recognized as fluvial deposits.