This work involves a multy-proxy approach of taphonomic features of the extinct giant ground slot... more This work involves a multy-proxy approach of taphonomic features of the extinct giant ground sloth Lestodon armatus (Xenarthra, Mylodontidae). The study is based on paleohistological, mineralogical, and geochemical analyses from the Late Pleistocene Playa del Barco site (Buenos Aires Province, Argentina). Transverse thin sections of ribs and vertebrae were studied under light microscope, polarizing petrographic microscope, and scanning electron microscope (SEM), combined with chemical analysis using energy dispersive spectroscopy (EDS) and micro-X-ray diffraction (μXRD). The internal crystalline structure and mineral composition remains almost unaltered. The bone microstructure is well preserved in all the samples, although it was affected by different types of microfractures and infillings. Numerous radial microcracks were identified in the secondary osteons of all specimens evidencing wet depositional environment. The mineralogical and geochemical composition of the infillings and encrustations indicates that the enrichment with new elements was due to direct exchange with the sediments in which they were buried. Mineralogical evidence from the infillings allows to identify different diagenetic pathways; most of the skeletal elements were quickly buried in the vadose zone, while others were buried in the phreatic zone, directly or after some time immersed in a continental aquatic context. The fossildiagenetic information obtained from the Lestodon armatus fossils provides novel information to interpret and reconstruct the whole taphonomic history and the environmental and climatic conditions that favored the preservation of the Playa del Barco fossil assemblage during the end of the Last Glacial Maximum.
Peltephilidae (Xenarthra, Cingulata) is an ancient lineage of medium–large-sized ‘armadillos’ fro... more Peltephilidae (Xenarthra, Cingulata) is an ancient lineage of medium–large-sized ‘armadillos’ from South America, characterized by chisel-shaped molariforms, a U-shaped dental arcade, and cephalic osteoderms modified into hornlike structures. Although the biochron of the group extends from the early Eocene to the Late Miocene, the most abundant and complete records come from the Early Miocene of Patagonia. Remains from the Late Miocene are very scarce, and the last records of the group are from the Chasicoan Stage (Tortonian). The only taxon known from this interval is Epipeltephilus kanti from the Arroyo Chasicó Formation (9.23 +- 0.09 Ma; Buenos Aires Province, Argentina), a species previously represented only by a few isolated osteoderms. Here we report new remains assigned to E. kanti from the Late Miocene of Loma de Las Tapias Formation (c. 9.0–7.8 Ma; San Juan Province, Argentina), including a hemimandible and several fixed and mobile osteoderms. These new specimens constitute the youngest record of Peltephilidae. The inclusion of E. kanti within Epipeltephilus and the monophyly of the genera Peltephilus and Epipeltephilus are corroborated for the first time through a cladistic analysis. The decline and eventual disappearance of this ‘armadillo’ group in the Late Miocene is chronologically coincident with the replacement of subtropical/tropical environments by more open and arid ones and with the proliferation of other large armadillos such as Vetelia, Macrochorobates, and Macroeuphractus.
is a locality with fossiliferous outcrops of the Cerro Azul Formation in La Pampa Province (centr... more is a locality with fossiliferous outcrops of the Cerro Azul Formation in La Pampa Province (central Argentina). First fossil remains were known in 1999 and assigned to the Chasicoan Stage/Age (Late Miocene, Tortonian) after the presence of the Octodontoidea rodent Chasichimys bonaerense. Later references to vertebrate remains were scarce and mostly limited to some mentioned taxa in broader faunal contexts. Now, we present a detailed taxonomic study of the entire mammal assemblage from Cerro Patagua, which evidences that most taxa are typical of the Chasicoan Stage/Age. A peculiar enterolith-like structure, recovered from loess levels, is also described, and several taphonomic aspects observed on fossils are related to their level of provenance. In addition, we offer stratigraphical interpretations of the Cerro Azul Formation and a geomorphological analysis of the Cerro Patagua area, and provide a detrital zircon dating of 12.3 ± 1.8 Ma. This result reflects the time interval 14.1-10.5 Ma, a temporal range that includes the Serravalian Stage (late Middle Miocene) and could indicate that the oldest synorogenic deposits could have begun to accumulate at the end of this stage. Even considering the minimum age of this interval (Tortonian Stage), this dating is the oldest obtained for the Cerro Azul Formation, compared with previous published data from Arroyo Chasicó locality (9.43-9.07 Ma). This assignment could explain that taxa from Cerro Patagua show affinities with Late Miocene mammal assemblages from central Argentina, as well as with older faunas from Patagonia and Bolivia.
Arenas Blancas is a poorly known fossiliferous site located in the lower reach of the Chasicó cre... more Arenas Blancas is a poorly known fossiliferous site located in the lower reach of the Chasicó creek (Buenos Aires Province, Argentina), with great relevance from a biostratigraphic viewpoint. The Macrochorobates scalabrinii Biozone was defined in this site, proposed as the biostratigraphic basis of the early Huayquerian Stage/Age (Late Miocene); however, the geological context and faunal record of this site have never been studied in detail. In this work, we perform a multi-proxy analysis of the Arenas Blancas site, as well as a nearby site here called Curva de la Vaca, and provide new interpretations on their origin, age, and biostratigraphy. Sedimentological, stratigraphic, and geomorphological characteristics of both sites suggest that the sequences include fluvial/alluvial deposits that represent Quaternary terraces. The taxonomic analysis of the Arenas Blancas faunal assemblage evidences the presence of 14 mammal taxa, together with some fishes, reptiles, and birds; the assemblage is correlated with the assemblage from the Cerro Azul Formation assigned to the Chasicoan Stage/Age (Late Miocene), also recovered from the lower reach of the Chasicó creek. The use of the taxa proposed in previous works to characterize the Macrochorobates scalabrinii Biozone (including this species) is not supported due to their taxonomic status and/or temporal distribution. Taphonomic evaluation indicates that the assemblage is constituted by reworked specimens; in this frame, it is proposed that fluvio/alluvial events, occurred during the Late Pleistocene-Holocene, eroded the Upper Miocene substrate and reworked fossil remains. Based on the present evidence, the Macrochorobates scalabrinii Biozone is here rejected as a valid biostratigraphic unit.
Diverse modifications of the original morphological features occur throughout the taphonomic hist... more Diverse modifications of the original morphological features occur throughout the taphonomic history of osteological remains, which may lead in erroneous interpretations about the formation of an accumulation as well as taxonomic misidentifications. Here, we present a neo-taphonomic study in order to analyze and interpret the modifications generated by digestion on osteoderms of the armadillo Dasypus novemcinctus obtained from scats produced by Puma concolor. Results reveal intense breakage and modifications of the articular and broken edges, dorsal surface, bone tissues, and ornamentation pattern of the osteoderms. This work describes for the first time the modifications caused by digestion in armadillo osteoderms, improving the knowledge of preservation of this type of skeletal element and providing a modern analog that can be used to distinguish archeological and paleontological accumulations formed by predators from those generated by other processes. The recognition that digestion modifies the original ornamentation pattern is particularly significant because ornamentation features are used in nearly all taxonomic and phylogenetic studies of fossil cingulates. We use this new information to re-evaluate osteoderms recovered from carnivore coprolites of the classic Middle Miocene La Venta site (Colombia), which formed the basis for recognizing and characterizing the dasypodid species Nanoastegotherium prostatum. We highlight the importance of knowing with certainty the origin and taphonomic history of remains since, in the particular case of cingulates, taxonomic identification also has important biostratigraphic, paleoecological, paleoenvironmental, and paleobiogeographical implications.
Hitherto, only the Proterotheriidae Ameghino, 1887 litopterns from the Cerro Azul Formation (Chas... more Hitherto, only the Proterotheriidae Ameghino, 1887 litopterns from the Cerro Azul Formation (Chasicoan-Huayquerian Stages/Ages; Late Miocene-Early Pliocene) in La Pampa Province had been studied, recognizing Proterotheriidae indet. at Cerro La Bota, Diplasiotherium pampa Soria, 2001 at several localities, Eoauchenia primitiva Ameghino, 1887 at El Guanaco, and cf. Brachytherium cuspidatum Ameghino, 1883 at Salinas Grandes de Hidalgo, which added to Epecuenia thoatherioides Cabrera, 1939 from Laguna Epecuén in Buenos Aires Province; this locality also yielded the Macraucheniidae Gervais, 1855 Huayqueriana cristata (Rovereto, 1914). Now, we enlarge the study to both litoptern families and to the outcrops of the Cerro Azul Formation in Buenos Aires Province. Concerning Macraucheniidae, we recognize: Scalabrinitherium bravardi Ameghino, 1883 at Salinas Grandes de Hidalgo, Telén, and Guatraché (La Pampa), and Laguna Epecuén (Buenos Aires); Paranauchenia denticulata Ameghino, 1891, Promacrauchenia sp., and Cullinia sp. at Salinas Grandes de Hidalgo and Laguna Chillhué (La Pampa); cf. Oxyodontherium zeballosi Ameghino, 1883b at Laguna del Monte (Buenos Aires); and Promacrauchenia sp. at Cantera Relleno Sanitario (Buenos Aires). Referring to Proterotheriidae, new results reveal the first record of Diplasiotherium pampa in Buenos Aires (Arroyo El Venado) and Neobrachytherium sp. at Laguna Epecuén and Laguna La Paraguaya (Buenos Aires). The litoptern diversity is close to that from the Lower Member of the Ituzaingó Formation, Late Miocene, Entre Ríos Province. The litoptern record does not provide confident data to support or reject the established relative biostratigraphic succession of localities of the Cerro Azul Formation, which is mainly based on some rodent lineages.
Among extinct sloths, Nothrotheriidae nothrotheriines are characterised by caniniforms (when pres... more Among extinct sloths, Nothrotheriidae nothrotheriines are characterised by caniniforms (when present) separated by a diastema from the molariform tooth row and quadrangular, rectangular or trapezoidal molariforms with longitudinal grooves on the lingual and labial surfaces. The subfamily Nothrotheriinae is recorded from the Middle Miocene of Bolivia and Argentina to the Pleistocene of different regions of South America, Central America and North America. Neogene well-known representatives include Pronothrotherium, Huilabradys, Mionothropus, Aymaratherium, Lakukullus and the recently defined genus Mcdonaldocnus, whose remains were found from Argentina, Colombia, Uruguay, Peru, Brazil and Bolivia. Mcdonaldocnus includes materials from Argentina and Bolivia previously assigned as 'Xyophorus'. New records from Late Miocene levels of the Cerro Azul Formation cropping out in the Chasicó creek locality, Buenos Aires Province, and in the localities of Telén and Loventué, La Pampa Province, allow us to describe cranio-dental remains of Nothrotheriinae Mcdonaldocnus bondesioi and Mcdonaldocnus sp., respectively. The identification of Mcdonaldocnus sp. in the Cerro Azul Formation at La Pampa Province constitutes the first record of Nothrotheriinae for this province.
The subfamily Doedicurinae is a monophyletic group of glyptodonts with their own anatomical featu... more The subfamily Doedicurinae is a monophyletic group of glyptodonts with their own anatomical features and is mostly known on the basis of the Pleistocene genus Doedicurus, one of the largest recorded taxa. The most distinctive character of the subfamily, unique within Cingulata, include the absence of ornamentation with large foramina, on the exposed surface of the carapace osteoderms. In terminal forms of the late Pleistocene, osteoderms have large foramina which tend to cross the entire thickness. The knowledge of the late Neogene diversity of the clade, as well as its evolutionary and geographical history, has increased in recent years, with important records in Argentina, where two late Miocene-Pliocene species are recognised: Eleutherocercus solidus from Catamarca and Tucumán provinces, and Eleutherocercus antiquus from Buenos Aires province. The most complete skull of E. antiquus from the early Pliocene Monte Hermoso Formation (ca. 5-4.2 Ma) is reported here. The specimen studied shows a conspicuous pathology on the parietal bones, first reported for fossil cingulates. In addition, the carapace of E. solidus is first described, on the basis of a partially complete specimen from the late Miocene-Pliocene (unknown stratigraphic level) from Tucumán province. Previous phylogenetic hypotheses of the relationships within the Doedicurinae, as well as their relationship with the remaining clades of Glyptodontidae, is tested in this study, adding new synapomorphies to the subfamily. The comparative study suggests that a third species previously proposed (E. paranaensis) from the 'Mesopotamiense' (late Miocene, Northeastern region of Argentina), must be considered as Eleutherocercus sp. Since their oldest record in the late Miocene, the latitudinal distribution of the Doedicurinae seems to have expanded rapidly reaching middle latitudes, particularly during the Pliocene, but during the Pleistocene (particularly the final lapse of this period), they began to retract latitudinally.
During the Pleistocene intense climatic changes occurred corresponding with the alternation of in... more During the Pleistocene intense climatic changes occurred corresponding with the alternation of interglacial and glacial periods. By means of stable isotope analysis on fossil mammals, this research allows the assessment of the palaeoecological and palaeoclimatic conditions, including the possible scenarios for the atmospheric circulation pattern during three key phases of the late Pleistocene in the Pampean region of Argentina: Last Interglacial (LIG, MIS 5e; unpublished data), Last Glacial Maximum (LGM; 28,170e19,849 cal BP yrs), and post-Last Glacial Maximum (post-LGM, 17,281e11,500 cal BP yrs). Tooth enamel d 13 C values of mammals from the Last Glacial Maximum showed an increase in C 4 plants consumption compared to the other two phases studied, which may be related to a reduction in forest cover due to a combination of environmental factors such as decreased pCO 2 atm and increased aridity. We evaluated mean annual precipitation (MAP) and mean annual temperature (MAT) variability from tooth enamel d 13 C and d 18 O values, which showed a greater variation in precipitation between phases than in temperature. This result enabled us to propose two climate regimes for the studied temporal sequence, an arid-temperate regime, and a humid-temperate regime, which were mostly regulated by variations in atmospheric circulation.
Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) ar... more Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) are taphonomically analysed. All remains form a single sample recovered from Chasicoan sediments (facies FA2) of the Cerro Azul Formation, constituted by a lateral and vertical erosive superposition of sandstone and conglomeratic bodies, formed by episodic development of perennial streams without flow division on a loessic substrate. The analysis reveals that micro- and macromammal remains originally accumulated independently and differently. Once each type of accumulation was buried in a loessic context, the development of streams gave place to a reworking process of fossils that were finally incorporated together into the stream channel. Taphonomic characteristics of micromammals are interpreted as the result of the leftover prey accumulated by predators, probably at a den site. Instead, the macromammals respond to an attritional accumulation of individuals inhabiting the area. Even considering the reworking as an important process that affected this assemblage, the taxonomic and taphonomic evidences suggest a relatively short time for its formation. The different taphonomic histories of the remains evidence a complex association that differs from other assemblages from the Cerro Azul Formation previously analysed, and it is here assigned to the channel-lag taphonomic mode.
Experiments based on the premise of uniformitarism are an effective tool to establish patterns of... more Experiments based on the premise of uniformitarism are an effective tool to establish patterns of taphonomic processes acting either before, or after, burial. One process that has been extensively investigated experimentally is the impact of trampling to large mammal bones. Since trampling marks caused by sedimentary friction strongly mimic cut marks made by humans using stone tools during butchery, distinguishing the origin of such modifications is especially relevant to the study of human evolution. In contrast, damage resulting from trampling on small mammal fossil bones has received less attention, despite the fact that it may solve interesting problems relating to site formation processes. While it has been observed that the impact of compression depends on the type of substrate and dryness of the skeletal elements, the fragility of small mammal bones may imply that they will break as a response to compression. Here, we have undertaken a controlled experiment using material resistance compression equipment to simulate a preliminary experiment, previously devised by one of us, on human trampling of owl pellets. Our results demonstrate that different patterns of breakage can be distinguished under wet and dry conditions in mandibles, skulls and long bones that deform or break in a consistent way. Further, small compact bones almost always remain intact, resisting breakage under compression. The pattern obtained here was applied to a Pleistocene small mammal fossil assemblage from Wonderwerk Cave (South Africa). This collection showed unusually extensive breakage and skeletal element representation that could not be entirely explained by excavation procedures or digestion by the predator. We propose that trampling was a significant factor in small mammal bone destruction atWonderwerk Cave, partly the product of trampling caused by the raptor that introduced the microfauna into the cave, as well as by hominins and other terrestrial animals that entered the cave and trampled pellets covering the cave floor.
The first unequivocal records of teratornithid birds from the Pleistocene of South America are he... more 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 capaci...
Glyptodonts (Xenarthra, Cingulata) are one of the most amazing Cenozoic South American mammals, w... more Glyptodonts (Xenarthra, Cingulata) are one of the most amazing Cenozoic South American mammals, with some terminal forms reaching ca. two tons. The Paleogene record of glyptodonts is still poorly known, although some of their diversification is observable in Patagonian Argentina. Since the early and middle Miocene (ca. 19-13 Ma), two large clades can be recognized in South America. One probably has a northern origin (Glyptodontinae), while the other one, called the "austral clade", is interpreted to have had an austral origin, with the oldest records represented by the "Propalaehoplophorinae" from the late early Miocene of Patagonian Argentina. In this scenario, the extra-Patagonian radiations are still poorly known, despite their importance for understanding the late Miocene and Pliocene diversity. Here, we carry out a comprehensive revision of late Miocene (Chasicoan Stage/Age) glyptodonts of central Argentina (Buenos Aires and San Juan provinces). Our results show that, contrary to what is traditionally assumed, it was a period of very low diversity, with only one species recognized in this region, Kelenkura castroi gen et sp. nov. Our phylogenetic analysis shows that this species represents the sister taxon of the remaining species of the "austral clade", representing the first branch of the extra-Patagonian radiation. Additionally, K. castroi is the first taxon showing a "fully modern" morphology of the caudal tube.
Rancho La Brea (California, USA) is the most emblematic Quaternary fossiliferous locality in the ... more 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 viewpoint, 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 preand 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.
Abstract Here we describe an isolated distal end of tarsometatarsus coming from the late Miocene ... more Abstract Here we describe an isolated distal end of tarsometatarsus coming from the late Miocene levels of the Loma de Las Tapias Formation (San Juan Province, Argentina). The specimen was identified as a Thinocoridae, and constitutes the oldest record for the clade. It also represents the only Tertiary finding for the family from South America and one of the scarce avian remains reported from central Argentina. This record provides new information on the palaeobiogeography of the clade.
The first unequivocal records of teratornithid birds from the Pleistocene of South America are he... more 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.
Vetelia is a Miocene genus of armadillos from Argentina and Chile, traditionally included within ... more Vetelia is a Miocene genus of armadillos from Argentina and Chile, traditionally included within the subfamily Euphrac tinae (Chlamyphoridae, Cingulata, Xenarthra). It includes the species Vetelia puncta (early-middle Miocene), Vetelia perforata (middle-late Miocene), and Vetelia gandhii (late Miocene), mostly known by isolated osteoderms. In this con tribution, we provide the first description of the skull for this genus, based on new materials (PVSJ289 and PVSJ154) here assigned to V. gandhii. A detailed characterization allows us to amend the diagnosis of the three known species, and to include, for the first time, the genus Vetelia into a morphological phylogenetic analysis. Phylogenetic results reveal a closer affinity to the Tolypeutinae, including the extant genera Priodontes (giant armadillos), Cabassous (nakedtailed armadillos), and Tolypeutes (three banded armadillos), and the fossil genera Pedrolypeutes and Kuntinaru, than to the Euphractinae. More specifically, Vetelia is included within the Priodontini, as sister group of the clade composed by Cabassous + Priodontes. Taking into account the scarce record of fossil Tolypeutinae, this new proposal fills an impor tant temporal gap in the evolutionary history of this linage. Finally, we also provide new information on the diagnostic morphological characters of the Priodontini and Tolypeutini.
The apparently regular and favourable climate that characterizes the Holocene as an interglacial ... more 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 choro-type 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.
Recently, Barasoain et al. (2020) described a new genus and
species of a chlamyphorine (Cingulata... more Recently, Barasoain et al. (2020) described a new genus and species of a chlamyphorine (Cingulata, Chlamyphoridae), Chlamyphractus dimartinoi, from the upper Miocene of southwestern Buenos Aires Province, Argentina. This description documents the first fossil record of a ‘fairy armadillo.’ However, the generic name proposed by the authors had previously been used to nominate a fossil glyptodont (Cingulata, Glyptodontidae), Chlamyphractus Castellanos, 1940. The name Chlamyphractus Castellanos, 1940, was mentioned in several studies (Fernicola, 2008; González-Ruiz et al., 2017; and references therein). Although some authors consider this genus as a nomen dubium (e.g., Scillato-Yané et al., 2013; González-Ruiz et al., 2017), the name is still available (Neave, 2004). In this context, it is necessary to propose a new name to replace Chlamyphractus Barasoain et al., 2020. Here, we propose Chlamydophractus, gen. nov., with the type species Chlamyphractus dimartinoi Barasoain et al., 2020, resulting in the new combination Chlamydophractus dimartinoi (Barasoain et al., 2020).
This work involves a multy-proxy approach of taphonomic features of the extinct giant ground slot... more This work involves a multy-proxy approach of taphonomic features of the extinct giant ground sloth Lestodon armatus (Xenarthra, Mylodontidae). The study is based on paleohistological, mineralogical, and geochemical analyses from the Late Pleistocene Playa del Barco site (Buenos Aires Province, Argentina). Transverse thin sections of ribs and vertebrae were studied under light microscope, polarizing petrographic microscope, and scanning electron microscope (SEM), combined with chemical analysis using energy dispersive spectroscopy (EDS) and micro-X-ray diffraction (μXRD). The internal crystalline structure and mineral composition remains almost unaltered. The bone microstructure is well preserved in all the samples, although it was affected by different types of microfractures and infillings. Numerous radial microcracks were identified in the secondary osteons of all specimens evidencing wet depositional environment. The mineralogical and geochemical composition of the infillings and encrustations indicates that the enrichment with new elements was due to direct exchange with the sediments in which they were buried. Mineralogical evidence from the infillings allows to identify different diagenetic pathways; most of the skeletal elements were quickly buried in the vadose zone, while others were buried in the phreatic zone, directly or after some time immersed in a continental aquatic context. The fossildiagenetic information obtained from the Lestodon armatus fossils provides novel information to interpret and reconstruct the whole taphonomic history and the environmental and climatic conditions that favored the preservation of the Playa del Barco fossil assemblage during the end of the Last Glacial Maximum.
Peltephilidae (Xenarthra, Cingulata) is an ancient lineage of medium–large-sized ‘armadillos’ fro... more Peltephilidae (Xenarthra, Cingulata) is an ancient lineage of medium–large-sized ‘armadillos’ from South America, characterized by chisel-shaped molariforms, a U-shaped dental arcade, and cephalic osteoderms modified into hornlike structures. Although the biochron of the group extends from the early Eocene to the Late Miocene, the most abundant and complete records come from the Early Miocene of Patagonia. Remains from the Late Miocene are very scarce, and the last records of the group are from the Chasicoan Stage (Tortonian). The only taxon known from this interval is Epipeltephilus kanti from the Arroyo Chasicó Formation (9.23 +- 0.09 Ma; Buenos Aires Province, Argentina), a species previously represented only by a few isolated osteoderms. Here we report new remains assigned to E. kanti from the Late Miocene of Loma de Las Tapias Formation (c. 9.0–7.8 Ma; San Juan Province, Argentina), including a hemimandible and several fixed and mobile osteoderms. These new specimens constitute the youngest record of Peltephilidae. The inclusion of E. kanti within Epipeltephilus and the monophyly of the genera Peltephilus and Epipeltephilus are corroborated for the first time through a cladistic analysis. The decline and eventual disappearance of this ‘armadillo’ group in the Late Miocene is chronologically coincident with the replacement of subtropical/tropical environments by more open and arid ones and with the proliferation of other large armadillos such as Vetelia, Macrochorobates, and Macroeuphractus.
is a locality with fossiliferous outcrops of the Cerro Azul Formation in La Pampa Province (centr... more is a locality with fossiliferous outcrops of the Cerro Azul Formation in La Pampa Province (central Argentina). First fossil remains were known in 1999 and assigned to the Chasicoan Stage/Age (Late Miocene, Tortonian) after the presence of the Octodontoidea rodent Chasichimys bonaerense. Later references to vertebrate remains were scarce and mostly limited to some mentioned taxa in broader faunal contexts. Now, we present a detailed taxonomic study of the entire mammal assemblage from Cerro Patagua, which evidences that most taxa are typical of the Chasicoan Stage/Age. A peculiar enterolith-like structure, recovered from loess levels, is also described, and several taphonomic aspects observed on fossils are related to their level of provenance. In addition, we offer stratigraphical interpretations of the Cerro Azul Formation and a geomorphological analysis of the Cerro Patagua area, and provide a detrital zircon dating of 12.3 ± 1.8 Ma. This result reflects the time interval 14.1-10.5 Ma, a temporal range that includes the Serravalian Stage (late Middle Miocene) and could indicate that the oldest synorogenic deposits could have begun to accumulate at the end of this stage. Even considering the minimum age of this interval (Tortonian Stage), this dating is the oldest obtained for the Cerro Azul Formation, compared with previous published data from Arroyo Chasicó locality (9.43-9.07 Ma). This assignment could explain that taxa from Cerro Patagua show affinities with Late Miocene mammal assemblages from central Argentina, as well as with older faunas from Patagonia and Bolivia.
Arenas Blancas is a poorly known fossiliferous site located in the lower reach of the Chasicó cre... more Arenas Blancas is a poorly known fossiliferous site located in the lower reach of the Chasicó creek (Buenos Aires Province, Argentina), with great relevance from a biostratigraphic viewpoint. The Macrochorobates scalabrinii Biozone was defined in this site, proposed as the biostratigraphic basis of the early Huayquerian Stage/Age (Late Miocene); however, the geological context and faunal record of this site have never been studied in detail. In this work, we perform a multi-proxy analysis of the Arenas Blancas site, as well as a nearby site here called Curva de la Vaca, and provide new interpretations on their origin, age, and biostratigraphy. Sedimentological, stratigraphic, and geomorphological characteristics of both sites suggest that the sequences include fluvial/alluvial deposits that represent Quaternary terraces. The taxonomic analysis of the Arenas Blancas faunal assemblage evidences the presence of 14 mammal taxa, together with some fishes, reptiles, and birds; the assemblage is correlated with the assemblage from the Cerro Azul Formation assigned to the Chasicoan Stage/Age (Late Miocene), also recovered from the lower reach of the Chasicó creek. The use of the taxa proposed in previous works to characterize the Macrochorobates scalabrinii Biozone (including this species) is not supported due to their taxonomic status and/or temporal distribution. Taphonomic evaluation indicates that the assemblage is constituted by reworked specimens; in this frame, it is proposed that fluvio/alluvial events, occurred during the Late Pleistocene-Holocene, eroded the Upper Miocene substrate and reworked fossil remains. Based on the present evidence, the Macrochorobates scalabrinii Biozone is here rejected as a valid biostratigraphic unit.
Diverse modifications of the original morphological features occur throughout the taphonomic hist... more Diverse modifications of the original morphological features occur throughout the taphonomic history of osteological remains, which may lead in erroneous interpretations about the formation of an accumulation as well as taxonomic misidentifications. Here, we present a neo-taphonomic study in order to analyze and interpret the modifications generated by digestion on osteoderms of the armadillo Dasypus novemcinctus obtained from scats produced by Puma concolor. Results reveal intense breakage and modifications of the articular and broken edges, dorsal surface, bone tissues, and ornamentation pattern of the osteoderms. This work describes for the first time the modifications caused by digestion in armadillo osteoderms, improving the knowledge of preservation of this type of skeletal element and providing a modern analog that can be used to distinguish archeological and paleontological accumulations formed by predators from those generated by other processes. The recognition that digestion modifies the original ornamentation pattern is particularly significant because ornamentation features are used in nearly all taxonomic and phylogenetic studies of fossil cingulates. We use this new information to re-evaluate osteoderms recovered from carnivore coprolites of the classic Middle Miocene La Venta site (Colombia), which formed the basis for recognizing and characterizing the dasypodid species Nanoastegotherium prostatum. We highlight the importance of knowing with certainty the origin and taphonomic history of remains since, in the particular case of cingulates, taxonomic identification also has important biostratigraphic, paleoecological, paleoenvironmental, and paleobiogeographical implications.
Hitherto, only the Proterotheriidae Ameghino, 1887 litopterns from the Cerro Azul Formation (Chas... more Hitherto, only the Proterotheriidae Ameghino, 1887 litopterns from the Cerro Azul Formation (Chasicoan-Huayquerian Stages/Ages; Late Miocene-Early Pliocene) in La Pampa Province had been studied, recognizing Proterotheriidae indet. at Cerro La Bota, Diplasiotherium pampa Soria, 2001 at several localities, Eoauchenia primitiva Ameghino, 1887 at El Guanaco, and cf. Brachytherium cuspidatum Ameghino, 1883 at Salinas Grandes de Hidalgo, which added to Epecuenia thoatherioides Cabrera, 1939 from Laguna Epecuén in Buenos Aires Province; this locality also yielded the Macraucheniidae Gervais, 1855 Huayqueriana cristata (Rovereto, 1914). Now, we enlarge the study to both litoptern families and to the outcrops of the Cerro Azul Formation in Buenos Aires Province. Concerning Macraucheniidae, we recognize: Scalabrinitherium bravardi Ameghino, 1883 at Salinas Grandes de Hidalgo, Telén, and Guatraché (La Pampa), and Laguna Epecuén (Buenos Aires); Paranauchenia denticulata Ameghino, 1891, Promacrauchenia sp., and Cullinia sp. at Salinas Grandes de Hidalgo and Laguna Chillhué (La Pampa); cf. Oxyodontherium zeballosi Ameghino, 1883b at Laguna del Monte (Buenos Aires); and Promacrauchenia sp. at Cantera Relleno Sanitario (Buenos Aires). Referring to Proterotheriidae, new results reveal the first record of Diplasiotherium pampa in Buenos Aires (Arroyo El Venado) and Neobrachytherium sp. at Laguna Epecuén and Laguna La Paraguaya (Buenos Aires). The litoptern diversity is close to that from the Lower Member of the Ituzaingó Formation, Late Miocene, Entre Ríos Province. The litoptern record does not provide confident data to support or reject the established relative biostratigraphic succession of localities of the Cerro Azul Formation, which is mainly based on some rodent lineages.
Among extinct sloths, Nothrotheriidae nothrotheriines are characterised by caniniforms (when pres... more Among extinct sloths, Nothrotheriidae nothrotheriines are characterised by caniniforms (when present) separated by a diastema from the molariform tooth row and quadrangular, rectangular or trapezoidal molariforms with longitudinal grooves on the lingual and labial surfaces. The subfamily Nothrotheriinae is recorded from the Middle Miocene of Bolivia and Argentina to the Pleistocene of different regions of South America, Central America and North America. Neogene well-known representatives include Pronothrotherium, Huilabradys, Mionothropus, Aymaratherium, Lakukullus and the recently defined genus Mcdonaldocnus, whose remains were found from Argentina, Colombia, Uruguay, Peru, Brazil and Bolivia. Mcdonaldocnus includes materials from Argentina and Bolivia previously assigned as 'Xyophorus'. New records from Late Miocene levels of the Cerro Azul Formation cropping out in the Chasicó creek locality, Buenos Aires Province, and in the localities of Telén and Loventué, La Pampa Province, allow us to describe cranio-dental remains of Nothrotheriinae Mcdonaldocnus bondesioi and Mcdonaldocnus sp., respectively. The identification of Mcdonaldocnus sp. in the Cerro Azul Formation at La Pampa Province constitutes the first record of Nothrotheriinae for this province.
The subfamily Doedicurinae is a monophyletic group of glyptodonts with their own anatomical featu... more The subfamily Doedicurinae is a monophyletic group of glyptodonts with their own anatomical features and is mostly known on the basis of the Pleistocene genus Doedicurus, one of the largest recorded taxa. The most distinctive character of the subfamily, unique within Cingulata, include the absence of ornamentation with large foramina, on the exposed surface of the carapace osteoderms. In terminal forms of the late Pleistocene, osteoderms have large foramina which tend to cross the entire thickness. The knowledge of the late Neogene diversity of the clade, as well as its evolutionary and geographical history, has increased in recent years, with important records in Argentina, where two late Miocene-Pliocene species are recognised: Eleutherocercus solidus from Catamarca and Tucumán provinces, and Eleutherocercus antiquus from Buenos Aires province. The most complete skull of E. antiquus from the early Pliocene Monte Hermoso Formation (ca. 5-4.2 Ma) is reported here. The specimen studied shows a conspicuous pathology on the parietal bones, first reported for fossil cingulates. In addition, the carapace of E. solidus is first described, on the basis of a partially complete specimen from the late Miocene-Pliocene (unknown stratigraphic level) from Tucumán province. Previous phylogenetic hypotheses of the relationships within the Doedicurinae, as well as their relationship with the remaining clades of Glyptodontidae, is tested in this study, adding new synapomorphies to the subfamily. The comparative study suggests that a third species previously proposed (E. paranaensis) from the 'Mesopotamiense' (late Miocene, Northeastern region of Argentina), must be considered as Eleutherocercus sp. Since their oldest record in the late Miocene, the latitudinal distribution of the Doedicurinae seems to have expanded rapidly reaching middle latitudes, particularly during the Pliocene, but during the Pleistocene (particularly the final lapse of this period), they began to retract latitudinally.
During the Pleistocene intense climatic changes occurred corresponding with the alternation of in... more During the Pleistocene intense climatic changes occurred corresponding with the alternation of interglacial and glacial periods. By means of stable isotope analysis on fossil mammals, this research allows the assessment of the palaeoecological and palaeoclimatic conditions, including the possible scenarios for the atmospheric circulation pattern during three key phases of the late Pleistocene in the Pampean region of Argentina: Last Interglacial (LIG, MIS 5e; unpublished data), Last Glacial Maximum (LGM; 28,170e19,849 cal BP yrs), and post-Last Glacial Maximum (post-LGM, 17,281e11,500 cal BP yrs). Tooth enamel d 13 C values of mammals from the Last Glacial Maximum showed an increase in C 4 plants consumption compared to the other two phases studied, which may be related to a reduction in forest cover due to a combination of environmental factors such as decreased pCO 2 atm and increased aridity. We evaluated mean annual precipitation (MAP) and mean annual temperature (MAT) variability from tooth enamel d 13 C and d 18 O values, which showed a greater variation in precipitation between phases than in temperature. This result enabled us to propose two climate regimes for the studied temporal sequence, an arid-temperate regime, and a humid-temperate regime, which were mostly regulated by variations in atmospheric circulation.
Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) ar... more Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) are taphonomically analysed. All remains form a single sample recovered from Chasicoan sediments (facies FA2) of the Cerro Azul Formation, constituted by a lateral and vertical erosive superposition of sandstone and conglomeratic bodies, formed by episodic development of perennial streams without flow division on a loessic substrate. The analysis reveals that micro- and macromammal remains originally accumulated independently and differently. Once each type of accumulation was buried in a loessic context, the development of streams gave place to a reworking process of fossils that were finally incorporated together into the stream channel. Taphonomic characteristics of micromammals are interpreted as the result of the leftover prey accumulated by predators, probably at a den site. Instead, the macromammals respond to an attritional accumulation of individuals inhabiting the area. Even considering the reworking as an important process that affected this assemblage, the taxonomic and taphonomic evidences suggest a relatively short time for its formation. The different taphonomic histories of the remains evidence a complex association that differs from other assemblages from the Cerro Azul Formation previously analysed, and it is here assigned to the channel-lag taphonomic mode.
Experiments based on the premise of uniformitarism are an effective tool to establish patterns of... more Experiments based on the premise of uniformitarism are an effective tool to establish patterns of taphonomic processes acting either before, or after, burial. One process that has been extensively investigated experimentally is the impact of trampling to large mammal bones. Since trampling marks caused by sedimentary friction strongly mimic cut marks made by humans using stone tools during butchery, distinguishing the origin of such modifications is especially relevant to the study of human evolution. In contrast, damage resulting from trampling on small mammal fossil bones has received less attention, despite the fact that it may solve interesting problems relating to site formation processes. While it has been observed that the impact of compression depends on the type of substrate and dryness of the skeletal elements, the fragility of small mammal bones may imply that they will break as a response to compression. Here, we have undertaken a controlled experiment using material resistance compression equipment to simulate a preliminary experiment, previously devised by one of us, on human trampling of owl pellets. Our results demonstrate that different patterns of breakage can be distinguished under wet and dry conditions in mandibles, skulls and long bones that deform or break in a consistent way. Further, small compact bones almost always remain intact, resisting breakage under compression. The pattern obtained here was applied to a Pleistocene small mammal fossil assemblage from Wonderwerk Cave (South Africa). This collection showed unusually extensive breakage and skeletal element representation that could not be entirely explained by excavation procedures or digestion by the predator. We propose that trampling was a significant factor in small mammal bone destruction atWonderwerk Cave, partly the product of trampling caused by the raptor that introduced the microfauna into the cave, as well as by hominins and other terrestrial animals that entered the cave and trampled pellets covering the cave floor.
The first unequivocal records of teratornithid birds from the Pleistocene of South America are he... more 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 capaci...
Glyptodonts (Xenarthra, Cingulata) are one of the most amazing Cenozoic South American mammals, w... more Glyptodonts (Xenarthra, Cingulata) are one of the most amazing Cenozoic South American mammals, with some terminal forms reaching ca. two tons. The Paleogene record of glyptodonts is still poorly known, although some of their diversification is observable in Patagonian Argentina. Since the early and middle Miocene (ca. 19-13 Ma), two large clades can be recognized in South America. One probably has a northern origin (Glyptodontinae), while the other one, called the "austral clade", is interpreted to have had an austral origin, with the oldest records represented by the "Propalaehoplophorinae" from the late early Miocene of Patagonian Argentina. In this scenario, the extra-Patagonian radiations are still poorly known, despite their importance for understanding the late Miocene and Pliocene diversity. Here, we carry out a comprehensive revision of late Miocene (Chasicoan Stage/Age) glyptodonts of central Argentina (Buenos Aires and San Juan provinces). Our results show that, contrary to what is traditionally assumed, it was a period of very low diversity, with only one species recognized in this region, Kelenkura castroi gen et sp. nov. Our phylogenetic analysis shows that this species represents the sister taxon of the remaining species of the "austral clade", representing the first branch of the extra-Patagonian radiation. Additionally, K. castroi is the first taxon showing a "fully modern" morphology of the caudal tube.
Rancho La Brea (California, USA) is the most emblematic Quaternary fossiliferous locality in the ... more 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 viewpoint, 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 preand 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.
Abstract Here we describe an isolated distal end of tarsometatarsus coming from the late Miocene ... more Abstract Here we describe an isolated distal end of tarsometatarsus coming from the late Miocene levels of the Loma de Las Tapias Formation (San Juan Province, Argentina). The specimen was identified as a Thinocoridae, and constitutes the oldest record for the clade. It also represents the only Tertiary finding for the family from South America and one of the scarce avian remains reported from central Argentina. This record provides new information on the palaeobiogeography of the clade.
The first unequivocal records of teratornithid birds from the Pleistocene of South America are he... more 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.
Vetelia is a Miocene genus of armadillos from Argentina and Chile, traditionally included within ... more Vetelia is a Miocene genus of armadillos from Argentina and Chile, traditionally included within the subfamily Euphrac tinae (Chlamyphoridae, Cingulata, Xenarthra). It includes the species Vetelia puncta (early-middle Miocene), Vetelia perforata (middle-late Miocene), and Vetelia gandhii (late Miocene), mostly known by isolated osteoderms. In this con tribution, we provide the first description of the skull for this genus, based on new materials (PVSJ289 and PVSJ154) here assigned to V. gandhii. A detailed characterization allows us to amend the diagnosis of the three known species, and to include, for the first time, the genus Vetelia into a morphological phylogenetic analysis. Phylogenetic results reveal a closer affinity to the Tolypeutinae, including the extant genera Priodontes (giant armadillos), Cabassous (nakedtailed armadillos), and Tolypeutes (three banded armadillos), and the fossil genera Pedrolypeutes and Kuntinaru, than to the Euphractinae. More specifically, Vetelia is included within the Priodontini, as sister group of the clade composed by Cabassous + Priodontes. Taking into account the scarce record of fossil Tolypeutinae, this new proposal fills an impor tant temporal gap in the evolutionary history of this linage. Finally, we also provide new information on the diagnostic morphological characters of the Priodontini and Tolypeutini.
The apparently regular and favourable climate that characterizes the Holocene as an interglacial ... more 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 choro-type 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.
Recently, Barasoain et al. (2020) described a new genus and
species of a chlamyphorine (Cingulata... more Recently, Barasoain et al. (2020) described a new genus and species of a chlamyphorine (Cingulata, Chlamyphoridae), Chlamyphractus dimartinoi, from the upper Miocene of southwestern Buenos Aires Province, Argentina. This description documents the first fossil record of a ‘fairy armadillo.’ However, the generic name proposed by the authors had previously been used to nominate a fossil glyptodont (Cingulata, Glyptodontidae), Chlamyphractus Castellanos, 1940. The name Chlamyphractus Castellanos, 1940, was mentioned in several studies (Fernicola, 2008; González-Ruiz et al., 2017; and references therein). Although some authors consider this genus as a nomen dubium (e.g., Scillato-Yané et al., 2013; González-Ruiz et al., 2017), the name is still available (Neave, 2004). In this context, it is necessary to propose a new name to replace Chlamyphractus Barasoain et al., 2020. Here, we propose Chlamydophractus, gen. nov., with the type species Chlamyphractus dimartinoi Barasoain et al., 2020, resulting in the new combination Chlamydophractus dimartinoi (Barasoain et al., 2020).
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extends from the early Eocene to the Late Miocene, the most abundant and complete records come from the Early Miocene of Patagonia. Remains from the Late Miocene are very scarce, and the last records of the group are from the Chasicoan Stage (Tortonian). The only taxon known from this interval is Epipeltephilus kanti from the Arroyo Chasicó Formation (9.23 +- 0.09 Ma; Buenos Aires Province, Argentina), a species previously represented only by a few isolated osteoderms. Here we report new remains assigned to E. kanti from the Late Miocene of Loma de Las Tapias Formation (c. 9.0–7.8 Ma; San Juan Province, Argentina), including a hemimandible and several fixed and mobile osteoderms. These new specimens constitute the youngest record of Peltephilidae. The inclusion of E. kanti within Epipeltephilus and the monophyly of the genera Peltephilus and Epipeltephilus are corroborated for the first time through a cladistic analysis. The decline and eventual disappearance of this
‘armadillo’ group in the Late Miocene is chronologically coincident with the replacement of subtropical/tropical environments by more open and arid ones and with the proliferation of other large armadillos such as Vetelia,
Macrochorobates, and Macroeuphractus.
of the Cerro Azul Formation, constituted by a lateral and vertical erosive superposition of sandstone and conglomeratic bodies, formed by episodic development of perennial streams without flow division on a loessic substrate. The analysis reveals that micro- and macromammal remains originally accumulated independently and differently. Once each type of accumulation was buried in a loessic context, the development of streams gave place to a reworking process of fossils that were finally incorporated together into the stream channel. Taphonomic characteristics of micromammals are interpreted as the result of the leftover prey accumulated by predators, probably at a den site. Instead, the macromammals respond to an attritional accumulation of individuals inhabiting the area. Even considering the reworking as an important
process that affected this assemblage, the taxonomic and taphonomic evidences suggest a relatively short time for its formation. The different taphonomic histories of the remains evidence a complex association that
differs from other assemblages from the Cerro Azul Formation previously analysed, and it is here assigned to the channel-lag taphonomic mode.
trampling marks caused by sedimentary friction strongly mimic cut marks made by humans using stone tools during butchery, distinguishing the origin of such modifications is especially relevant to the study of human evolution. In contrast, damage resulting from trampling on small mammal
fossil bones has received less attention, despite the fact that it may solve interesting problems relating to site formation processes. While it has been observed that the impact of compression depends on the type of substrate and dryness of the skeletal elements, the fragility of small mammal bones may imply that they will break as a response to compression. Here, we have undertaken a controlled experiment using material resistance compression equipment to simulate a preliminary experiment, previously devised by one of us, on human trampling of owl pellets. Our results demonstrate that different patterns of breakage can be distinguished under wet and dry conditions in mandibles, skulls and long bones that deform or break in a consistent way. Further, small compact bones almost always remain intact, resisting breakage under compression. The pattern obtained here was applied to a Pleistocene small mammal fossil assemblage from Wonderwerk Cave (South Africa). This collection showed unusually extensive breakage and skeletal element representation that could not be entirely explained by excavation procedures or digestion by the predator. We propose that trampling was
a significant factor in small mammal bone destruction atWonderwerk Cave, partly the product of trampling caused by the raptor that introduced the microfauna into the cave, as well as by hominins and other terrestrial animals that entered the cave and trampled pellets covering the cave floor.
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.
species of a chlamyphorine (Cingulata, Chlamyphoridae), Chlamyphractus dimartinoi, from the upper Miocene of southwestern
Buenos Aires Province, Argentina. This description documents the first fossil record of a ‘fairy armadillo.’ However, the generic name proposed by the authors had previously been used to nominate a fossil glyptodont (Cingulata, Glyptodontidae), Chlamyphractus Castellanos, 1940.
The name Chlamyphractus Castellanos, 1940, was mentioned in several studies (Fernicola, 2008; González-Ruiz et al., 2017; and references therein). Although some authors consider this genus as a nomen dubium (e.g., Scillato-Yané et al., 2013; González-Ruiz et al., 2017), the name is still available (Neave, 2004). In this context, it is necessary to propose a new name to replace Chlamyphractus Barasoain et al., 2020. Here, we propose Chlamydophractus, gen. nov., with the type species
Chlamyphractus dimartinoi Barasoain et al., 2020, resulting in the new combination Chlamydophractus dimartinoi (Barasoain et al., 2020).
extends from the early Eocene to the Late Miocene, the most abundant and complete records come from the Early Miocene of Patagonia. Remains from the Late Miocene are very scarce, and the last records of the group are from the Chasicoan Stage (Tortonian). The only taxon known from this interval is Epipeltephilus kanti from the Arroyo Chasicó Formation (9.23 +- 0.09 Ma; Buenos Aires Province, Argentina), a species previously represented only by a few isolated osteoderms. Here we report new remains assigned to E. kanti from the Late Miocene of Loma de Las Tapias Formation (c. 9.0–7.8 Ma; San Juan Province, Argentina), including a hemimandible and several fixed and mobile osteoderms. These new specimens constitute the youngest record of Peltephilidae. The inclusion of E. kanti within Epipeltephilus and the monophyly of the genera Peltephilus and Epipeltephilus are corroborated for the first time through a cladistic analysis. The decline and eventual disappearance of this
‘armadillo’ group in the Late Miocene is chronologically coincident with the replacement of subtropical/tropical environments by more open and arid ones and with the proliferation of other large armadillos such as Vetelia,
Macrochorobates, and Macroeuphractus.
of the Cerro Azul Formation, constituted by a lateral and vertical erosive superposition of sandstone and conglomeratic bodies, formed by episodic development of perennial streams without flow division on a loessic substrate. The analysis reveals that micro- and macromammal remains originally accumulated independently and differently. Once each type of accumulation was buried in a loessic context, the development of streams gave place to a reworking process of fossils that were finally incorporated together into the stream channel. Taphonomic characteristics of micromammals are interpreted as the result of the leftover prey accumulated by predators, probably at a den site. Instead, the macromammals respond to an attritional accumulation of individuals inhabiting the area. Even considering the reworking as an important
process that affected this assemblage, the taxonomic and taphonomic evidences suggest a relatively short time for its formation. The different taphonomic histories of the remains evidence a complex association that
differs from other assemblages from the Cerro Azul Formation previously analysed, and it is here assigned to the channel-lag taphonomic mode.
trampling marks caused by sedimentary friction strongly mimic cut marks made by humans using stone tools during butchery, distinguishing the origin of such modifications is especially relevant to the study of human evolution. In contrast, damage resulting from trampling on small mammal
fossil bones has received less attention, despite the fact that it may solve interesting problems relating to site formation processes. While it has been observed that the impact of compression depends on the type of substrate and dryness of the skeletal elements, the fragility of small mammal bones may imply that they will break as a response to compression. Here, we have undertaken a controlled experiment using material resistance compression equipment to simulate a preliminary experiment, previously devised by one of us, on human trampling of owl pellets. Our results demonstrate that different patterns of breakage can be distinguished under wet and dry conditions in mandibles, skulls and long bones that deform or break in a consistent way. Further, small compact bones almost always remain intact, resisting breakage under compression. The pattern obtained here was applied to a Pleistocene small mammal fossil assemblage from Wonderwerk Cave (South Africa). This collection showed unusually extensive breakage and skeletal element representation that could not be entirely explained by excavation procedures or digestion by the predator. We propose that trampling was
a significant factor in small mammal bone destruction atWonderwerk Cave, partly the product of trampling caused by the raptor that introduced the microfauna into the cave, as well as by hominins and other terrestrial animals that entered the cave and trampled pellets covering the cave floor.
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.
species of a chlamyphorine (Cingulata, Chlamyphoridae), Chlamyphractus dimartinoi, from the upper Miocene of southwestern
Buenos Aires Province, Argentina. This description documents the first fossil record of a ‘fairy armadillo.’ However, the generic name proposed by the authors had previously been used to nominate a fossil glyptodont (Cingulata, Glyptodontidae), Chlamyphractus Castellanos, 1940.
The name Chlamyphractus Castellanos, 1940, was mentioned in several studies (Fernicola, 2008; González-Ruiz et al., 2017; and references therein). Although some authors consider this genus as a nomen dubium (e.g., Scillato-Yané et al., 2013; González-Ruiz et al., 2017), the name is still available (Neave, 2004). In this context, it is necessary to propose a new name to replace Chlamyphractus Barasoain et al., 2020. Here, we propose Chlamydophractus, gen. nov., with the type species
Chlamyphractus dimartinoi Barasoain et al., 2020, resulting in the new combination Chlamydophractus dimartinoi (Barasoain et al., 2020).