Libro de resúmenes de las V Jornadas de Paleontología de la Cuenca Neuquina, que tuvieron lugar en la Ciudad de Senillosa (Neuquén, Argentina) del 9 al 13 de septiembre de 2025.
Eospalax, one of the only two extant genera within the Myospalacinae, has a high species richness. Each species is distinguished by unique cranial and dental morphologies, as well as variations in temporal and spatial distribution. Consequently, Eospalax serves as a reliable indicator for the biochronologic and paleoenvironmental studies of the Quaternary of East Asia. A recent discovery of a complete fossil skull in a conglomerate deposit, a part of the Lower Pleistocene Sanmen Formation, near Jianyucha Town, Zichang County, northern Shaanxi Province, has been subjected to a detailed analysis. The specimens were identified as Eospalax simplicidens, an extinct species of Eospalax, based on dental morphology. The recent discovery of E. simplicidens in Jianyucha offers significant insights into the species’ cranial morphology and contributes to a more comprehensive understanding of its geographical distribution. The distinctive feature of the posterodorsal location of the external acoustic meatus indicates either a plesiomorphy or an evolutionary convergence among E. simplicidens, African root rats (Tachyoryctes), and bamboo rats (Rhizomyini). A skull (IVPP V5398.1) and four upper jaws (V5398.2) from Gongwangling in Lantian, Shaanxi, previously identified as Myospalax fontanieri, is transferred to the species E. lingtaiensis. A skull (IVPP RV35055) from Jingou, Xin’an, Henan, previously identified as E. simplicidens, is transferred to the species E. youngianus. In this study, body mass estimates are made for extinct Eospalax. Both E. lingtaiensis and E. simplicidens are small-sized zokors, with an estimated body mass of less than or approximately 300 g, respectively.
Julia Van Orman, Oscar E. Wilson, Angeline Catena
et al.
Astrapotheres (Astrapotheria) are an order of South American native ungulates (SANUs), and the geologically youngest astrapotheres belong to the subfamily Uruguaytheriinae (Astrapotheriidae). In this study, we: (i) analyze uruguaytheriine remains from the late Middle Miocene Quebrada Honda Basin (QHB) of southern Bolivia; and (ii) discuss paleoecology of Bolivian astrapotheres based on new dental mesowear angle data and enamel stable carbon isotope (δ13C) data from these and other specimens. New material consists of a partial left maxilla preserving DP2–3 and an associated deciduous lower incisor. Two newly described specimens include a mostly complete m3 and a partial palate preserving left and right DP2–4. The QHB deciduous premolars are the first described for a uruguaytheriine and among the few described for astrapotheres. We conclude that the QHB specimens represent a new but unnamed species that likely does not pertain to any presently recognized genus. It differs from other uruguaytheriines in its intermediate size, relatively high-crowned teeth, presence of a lingually open M3 central valley, and absence of m3 hypoflexid, among other features. Astrapothere mesowear angle data from the QHB and slightly older Bolivian sites (Cerdas and Nazareno) suggest that Middle Miocene astrapotheres were browsers, perhaps resembling the extant black rhino (Diceros bicornis). New and updated enamel stable carbon isotope data suggest that QHB astrapotheres and toxodontid notoungulates fed on isotopically similar vegetation slightly more enriched (~1‰) than vegetation consumed by proterotheriid litopterns (Olisanophus spp.) and the notoungulate Hemihegetotherium trilobus. These data support paleopedology- and paleoichnology-based habitat reconstructions for the QHB that suggest it was more densely vegetated than Cerdas. Relatively enriched δ13C samples (> -7.0‰) from Cerdas and Quehua (Late Miocene) suggest that some Bolivian notoungulates were grazing on C4 vegetation, which casts doubt on the proposal that the southern Central Andean Plateau experienced significant uplift prior to ~9 Ma.
Olivier Maridet, Vlad A. Codrea, Cristina Fărcaș
et al.
A number of localities in Transylvania (Romania) have yielded vertebrate microfossil remains. Two localities have been stratigraphically and biochronologically dated to the late Eocene: i.e., Treznea and Bociu. The remaining three localities are dated to the early Oligocene: Mera, Cetățuie, and Suceag. The study of cricetid rodents corroborates the presence of this family in Eastern Europe during the late Eocene, as evidenced by the species Witenia sp., Bustrania cf. B. dissimile, and Eocricetodon cf. Eo. meridionalis. The cricetids identified in the sites of the early Oligocene age show a complete turnover and a notable increase in species richness following the Eocene/Oligocene boundary, with: Eucricetodon aff. Eu. huerzeleri, Tenuicricetodon arcemis gen. et sp. nov., Pseudocricetodon cf. Ps. montalbanensis, Paracricetodon cf. Pa. walgeri, Paracricetodon kavakderensis, Paracricetodon aff. Pa. stojonovici, and Paracricetodon wentgesi. In the context of the wider biogeographic history of Europe, these new discoveries indicate that Cricetidae arrived in Europe during at least two successive migrations from Asia in the late Eocene and earliest Oligocene. These migrations may have occurred via two different migration pathways through the north and south of Europe. In a second phase, Cricetidae arriving by the northern passway spread throughout Europe, whereas Cricetidae that arrived by the southern passway remained restricted to the central and southeastern Europe. The observations made on the Cricetidae allow for the proposal of a new, more general, scenario for the Eocene–Oligocene transition on a European scale, which is more complex than the “Grande Coupure” sensu stricto as initially proposed by Stehlin in 1909.
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. Horses 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. The first lineage is represented by the genus Equus, which appears in the Middle Pleistocene and presents anatomical features similar to those of a current horse. The second lineage is the species included in the genus Hippidion, which were horses with highly distinctive anatomical features that were first recorded in the late Pliocene. Both genera of horses include small (H. devillei, H. saldiasi, E. andium and E. insulatus) and large (E. neogeus and H. principale) forms, which dispersed in South America using two different routes. The possible model for this dispersal indicates that the small forms used the corridor of the Andes, while the larger horses dispersed along the eastern route and some coastal areas.
Mauricio A. Bigurrarena Ojeda, Soledad Gouiric-Cavalli, Leandro M. Perez
et al.
We present the study of the bromalites retrieved from the Upper Jurassic Ameghino (=Nordenskjöld) Formation at Longing Gap in the Antarctic Peninsula. The material was morphologically and chemically analyzed. We made a qualitative study and a taphonomic analysis of the specimens and tested paleobiological and paleoecological hypotheses. We conclude that the samples analyzed are coprolites and propose a new ichnotaxon, Antarctoscoprus longinensis ichnogen. and ichnosp. nov., characterized by being a small and flat coprolite differing from other ichnogenera by its composition, which consists mainly of actinopterygian remains (e.g., scales, vertebrae, skull bones, and teeth). Antarctoscoprus longinensis includes three morphotypes (i.e., circular, subcircular, and elongated) derived from an elongated three-dimensional original form by compactation. Based on the internal content, we infer the producers of the coprolites were carnivorous predators, putatively an ichthyophagous taxon. Due to the abundance of actinopterygians—mainly aspidorhynchids and ichthyodectids— and the size of the coprolites we propose macropredator fishes as the putative producers. The mainly undisrupted fish carcasses and coprolites allow us to conduct further studies that might lead to a better understanding of the ancient communities living in the Late Jurassic Sea that surrounded Antarctica.
Juan Martín Leardi, Martín Ezequiel Farina, Raúl Orencio Gómez
et al.
La Facultad de Ciencias Exactas y Naturales (FCEN) de la Universidad de Buenos Aires (UBA) se alojó inicialmente en la Manzana de las Luces de la Ciudad Autónoma de Buenos Aires, para luego reubicarse en los Pabellones I y II del complejo Ciudad Universitaria. Los estudios paleoherpetológicos en UBA se iniciaron con el Dr. Osvaldo Reig quien estuvo tres períodos en la institución: primero a fines de los 50, luego desde inicios a mediados de los 60 y finalmente a principios de los 80. Durante su primera época continuó con sus estudios de materiales fósiles de arcosaurios triásicos y anuros mesozoicos y cenozoicos. En su segundo período en la FCEN estuvo más enfocado en estudios microevolutivos basados en materiales actuales. La Dra. Ana María Báez se especializó en el estudio de los anfibios anuros, interactuando internacionalmente con destacados investigadores y formando profesionales en dicha temática y se desempeñó como profesora de la FCEN hasta el 2006. Tras su cese de actividades como profesora, este rol fue ocupado por su discípula la Dra. Claudia A. Marsicano, quien se dedicó al análisis de los anfibios temnospóndilos, aunque actualmente amplió sus estudios a las faunas de tetrápodos del Permo-Triásico de Gondwana. La Dra. C. A. Marsicano fundó el Laboratorio de Estudios Paleobiológicos en Ambientes Continentales y formó tesistas de grado y doctorado en paleoherpetología. En la actualidad los investigadores en paleoherpetología más jóvenes en la FCEN son Juan M. Leardi, que estudia crocodilomorfos, y Raúl O. Gómez, especializado en anuros y otros vertebrados.
Federico Gianechini, Leonardo Filippi, Ariel Méndez
et al.
The Cerro Overo-La Invernada area in north Patagonia has provided a rich record of Cretaceous continental tetrapods in the last two decades, mainly from the Bajo de la Carpa Formation (Upper Cretaceous, Santonian). The dinosaur fauna from this area is diverse, including several new taxa, with abelisaurid theropods particularly abundant. Recently, a new isolated caudal vertebra (MAU-Pv-CO-598) was here recovered. Although fragmentary, it shows features that differentiate it from other abelisaurid remains previously found in this area. It is considered a mid-caudal vertebra and is mainly characterized by a longitudinal groove on the ventral surface of the centrum; a scarcely elevated transverse process with an anteroposteriorly expanded and laterally concave distal end; a longitudinal dorsal crest anteriorly extended from the anterior border of the neural spine; and small tubercles extended from the ends of the zygapophyses, which are considered as accessory interlocking structures between vertebrae. Some characters, such as the dorsal longitudinal crest and the accessory tubercles of the zygapophyses, are present also in the non-brachyrostran abelisaurid Majungasaurus. However, the transverse process is similar to that of caudal vertebrae of non-furileusaur brachyrostrans, such as Ilokelesia, Ekrixinatosaurus, and Skorpiovenator. A phylogenetic analysis here conducted clusters MAU-Pv-Co-598 with the latter three taxa. MAU-Pv-CO-598 comes from lower levels of the Bajo de la Carpa Formation than the furileusaurs Viavenator and Llukalkan. The presence of a specimen with non-furileusaurian affinities in this formation indicates that a possible replacement from non-furileusaur to furileusaur brachyrostrans occurred during the Santonian, after the proposed Turonian faunal turnover.
Jorge D. Carrillo-Briceño, Rodolfo Sánchez, Torsten M. Scheyer
et al.
Abstract The Pliocene–Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus, Schizodon, Amblydoras, Scorpiodoras, and the pipesnake Anilius scytale, all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86Sr/88Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years.
VICTOR J. PEREZ, STEPHEN J. GODFREY, PHILLIP F. CHAPMAN
Direct evidence of chondrichthyan trophic interactions in the fossil record is largely limited to bite traces on prey items
but may also be found within the gut contents of exceptionally well-preserved individuals or as inclusions within coprolites.
Shark bite traces are typically observed on durable, bony skeletal elements. Previous publications have shown
shark bite traces on skeletal elements of fossil fishes, marine mammals, marine reptiles, and even a pterosaur, offering
direct evidence of active predation, failed predation, and/or scavenging. Herein, we describe the first evidence of shark
bite traces preserved on cartilaginous vertebral centra of other sharks. Four carcharhiniform centra have been identified
from the Neogene Atlantic Coastal Plain, bearing chondrichthyan bite traces, of which two have partial teeth still embedded
within them. In one specimen, CMM-V-2700, CT scans showed remodeling of the tissue around two partial teeth
embedded in the centrum, indicating that the bitten individual survived the encounter. While shark-on-shark predation is
common among living taxa, capturing evidence of these interactions in the fossil record is exceptionally rare.
Keegan R. Selig, Eric J. Sargis, Stephen G.B. Chester
et al.
AbstractTreeshrews are small, Indomalayan mammals closely related to primates. Previously, three-dimensional geometric morphometric analyses were used to assess patterns of treeshrew lower second molar morphology, which showed that the positions of molar landmarks covary with intraordinal systematics. Another analysis used dental topographic metrics to test patterns of functional dental morphology and found that molar curvature, complexity, and relief were an effective means for examining patterns of variation in treeshrew dietary ecology. Here, we build on these analyses by adding two fossil taxa,Prodendrogale yunnanicaQiu, 1986 from the Miocene of China andPtilocercus kylinLi and Ni, 2016 from the Oligocene of China. Our results show thatPr. yunnanicahad a dental bauplan more like that of a tupaiid than that of a ptilocercid, but that the extant tupaiids, includingTupaiaandDendrogale, are more similar to one another in this regard than any are toProdendrogale.This is contrary to our expectations asProdendrogaleis hypothesized to be most closely related toDendrogale. Ptilocercus kylin,which has been proposed to be the sister taxon ofPt. lowiiGray, 1848, is characterized by dental morphology like that ofPt. lowiiin crest and cuspal position but is interpreted to have been more frugivorous. It has been claimed thatPtilocercushas undergone little morphological change through time. Our results suggest thatPt. kylinwas more ecologically distinct fromPt. lowiithan previously proposed, providing a glimpse into a more complex evolutionary history of the group than had been inferred.
Foraminifera and calcareous nannofossils were studied in washed drill-cuttings of three wells from the Chilean sector of the Magallanes Basin. This contribution aims to identify, characterize and illustrate microfossil assemblages throughout the Cretaceous sedimentary record to integrate foraminiferal and the nannofossil data and improve further biostratigraphic studies in the basin. The analyzed Cretaceous succession in these wells corresponds to five discrete foraminiferal and nannofossil assemblages, which were recognized and are described here. The Valanginian–Hauterivian assemblage is characterized by a low diversity of benthic foraminifera typical of this age, like Lenticulina nodosa and Astacolus gibber, and nannofossil markers Lithraphidites bollii and Eiffellithus striatus; then, the Aptian–Albian begins with a predominance of radiolarians and transitions into a highly diverse assemblage comprising mainly gavelinellid benthics as well as abundant planktic foraminifera, which include Muricohedbergella delrioensis and M. portsdownensis, and diverse calcareous nannofossils with the marker Sollasites falklandensis. The Cenomanian can be distinguished by the presence of the nannofossil Corollithion kennedyi and also abundant planktic foraminifers; whilst the Coniacian–Campanian assemblage is characterized by planktic foraminifera like Costellagerina bulbosa, C. pilula, and Planoheterohelix reussi, as well as a diverse benthos and the nannofossil species Reinhardtites anthophorus, Eiffellithus eximius, and Eprolithus floralis. Finally, the Maastrichtian assemblage is characterized by mainly agglutinated foraminifera and few poorly preserved nannofossils. A detailed systematic list of both foraminiferal and nannofossil species is presented, intended to serve as a catalogue that will help to identify the different Cretaceous assemblages of the basin in future studies.
Carlos A. Luna, Ignacio A. Cerda, Alfredo E. Zurita
et al.
The subfamily Glyptodontinae (Xenarthra, Cingulata) comprises one of the most frequently recorded glyptodontids in South America. Recently, the North American genus Glyptotherium was recorded in South America, in addition to the genus Glyptodon. It has been shown that both genera shared the same geographic distribution in central-north and eastern areas of South America (Venezuela and Brazil, respectively). Although some characters allow differentiation between adult specimens of both genera, the morphological distinction between these two genera is rather difficult in juvenile specimens. In this contribution, a detailed morphological, morphometric and histological survey of a juvenile specimen of Glyptodontinae recovered from the Late Pleistocene of northern Brazil is performed. The relative lower osteoderms thickness, the particular morphology of the annular and radial sulci and the distal osseous projections of the caudal osteoderms suggest that the specimen belongs to the genus Glyptotherium. In addition, the validity of some statistical tools to distinguish between different ontogenetic stages and in some cases between genera is verified. The osteoderm microstructure of this juvenile individual is characterized by being composed of a cancellous internal core surrounded by a compact bone cortex. Primary bone tissue mostly consists of highly vascularized, woven-fibered bone tissue. Unlike that observed in adult Glyptodontinae, both the Sharpey fibers and the fibrous and laminar parallel bone tissue as secondary bone are absent. This study enhances our knowledge about those morphological and histological changes that occur through the ontogeny in glyptodonts.
This paper summarizes knowledge on the Neogene–Quaternary terrestrial fossil record from the Middle Kura Basin accumulated over a century and aims to its integration into the current research. This fossil evidence is essential in understanding the evolution of the Eurasian biome, since this territory is located at the border of Eastern Mediterranean and Central Asian regions. The general biostratigraphic framework suggests existence of two major intervals of the terrestrial fossil record in the area, spanning ca. 10–7 Ma and ca. 3–1 Ma, and points to an important hiatus between the late Miocene and late Pliocene. General aspects of the paleogeographic history and fossil record suggest that the biogeographic role of the Middle Kura Basin has been changing over geological time from a refugium (Khersonian) to a full-fledged part of the Greco-Iranian province (Meotian–Pontian). The dynamic environmental changes during the Quaternary do not depict this territory as a refugium in its general sense. The greatest value of this fossil record is the potential to understand a detailed history of terrestrial life during demise of late Miocene Hominoidea in Eurasia and early Homo dispersal out of Africa. Late Miocene record of the Middle Kura Basin captures the latest stage of the Eastern Paratethys regression, and among other fossils counts the latest and the easternmost occurence of dryopithecine, Udabnopithecus garedziensis, while the almost uninterrupted fossil record of the late Pliocene–Early Pleistocene covers the time interval of the early human occupation of Caucasus and Eurasia.
The Cretaceous sauropod material from Queensland, Australia, has been regarded as pertaining to a persistently primitive sauropod lineage (e.g., Coombs and Molnar). The specimens derive from the Toolebuc and Allaru (Albian marine) and Winton (Cenomanian continental) Formations. Recent phylogenetic analyses carried out by workers in Argentina, the USA and England permit a reassessment of this fragmentary material. As far as can be ascertained from the material, there is no indication from the character states that more than a single taxon is represented. Character states diagnostic of the Titanosauriforrnes, the Titanosauria, the Somphospondyli and the Titanosauridae are present. Thus the Queensland material does not pertain to cetiosaurids but belongs to titanosaurs, extending their range into Australia.
KEY WORDS. Sauropods. Austrosaurus. Titanosaurs. Cretaceous. Paleozoogeography.
G. Raquel Guerstein, Mirta Quattrocchio, Cecilia Deschamps
et al.
Abstract. Based on palynological studies, paleoclimatic trends were inferred for the Paleocene-Miocene of the marginal part of the Colorado Basin, Argentina. The data show warm and humid conditions during the Late Danian (Paleocene), a decline of temperature and humidity from the ?Mid Eocene to the Oligocene. Warm, humid conditions at the end of the Oligocene and Early Miocene were recorded; dry-temperate periods alternated with warmer humid ones during the Mid and Late Miocene. Temperature and humidity decreases coincide with sea level drops at Eocene/Oligocene, Early/Late Oligocene and Miocene/Oligocene boundaries. These paleoclimatic interpretations are compatible with those derived from calcareous microfossils of Colorado Basin, fossil plants from South America and global paleoclimatic changes inferred by other authors.
KEY WORDS. Argentina. Colorado Basin. Cenozoic pre-Pliocene. Palynology. Paleoenvironment. Paleoclimatical trends.
Resumen. FLUCTUACIONES PALEOAMBIENTALES DEL CENOZOICO (PRE-PLlOCENO) EN BASE A PALlNOMORPHS EN LA CUENCA DEL COLORADO, ARGENTINA. A partir de estudios palinológicos realizados en el sector marginal de la Cuenca del Colorado, se determinaron las tendencias paleoclimáticas durante el lapso Paleoceno- Mioceno. Para el Daniano tardío (Paleoceno) fueron inferidas condiciones cálidas y húmedas; para el Eoceno medio, templado-cálidas y húmedas; posterior disminución de la temperatura y humedad hasta el Oligoceno temprano; un mejoramiento climático para el Oligoceno tardío y Mioceno temprano; alternancia de períodos húmedos y cálidos con episodios relativamente más secos y fríos, durante el Mioceno medio y tardío. Las principales inflexiones en las tendencias de temperaturas reconocidas presentan una notable correspondencia con los límites estratigráficos convencionales. Los límites Eoceno/Oligoceno, Oligoceno inferior/Oligoceno superior y Mioceno/Plioceno coinciden con disminuciones de temperatura y humedad relacionadas con caídas relativas del nivel del mar. Las tendencias paleoclimáticas propuestas en este trabajo son compatibles con la información disponible acerca de microfósiles calcáreos de la Cuenca del Colorado, tafofloras de América del Sur y con las fluctuaciones paleoclimáticas de carácter global.
PALABRAS CLAVE. Argentina. Cuenca del Colorado. Cenozoico pre-Plioceno. Palinología. Paleoambientes. Tendencias paleoclimáticas.
The Paso Flores Formation exposed in the Pancho creek is mainly composed of fine-grained sediments. The pelitic rocks have been deposited from aqueous suspensions in deep lacustrine settings. Some upward fining sequences from shale to sandstone represent shallower lacustrine (wave formed) bars. To the top of the PFF, clast-supported conglomerates and cross-bedded sandstones show the progradation of a braided fluvial system upon the lacustrine succession. The paleofloristic association, composed of Corystosperms, Cycadals, Ginkgoals and Conifers, is characteristic for lacustrine deposits formed during the late Triassic.