Agustin G. Martinelli

Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" · Seccion Paleontologia de Vertebrados

We summarize here the Late Cretaceous vertebrate record of the Triângulo Mineiro (western portion of the Minas Gerais State, southeastern Brazil). All the specimens come from the Bauru Group (Bauru Basin) from the Adamantina (Campanian), Uberaba (Campanian) and Marília (Maastrichtian) formations. Vertebrate-bearing sites are distributed throughout...

We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically,...

The fossil record of non-mammaliaform probainognathian cynodonts is outstanding in the Late Triassic rocks of Brazil and Argentina. Approximately 15 genera are known, providing unique insights in the study of the major skeletal transformations prior to the mammalian condition. Globally, the diversity of probainognathians is possibly under-represent...

In this contribution we report the first occurrence of the enigmatic African probainognathian genus Aleodon in the Middle-early Late Triassic of several localities from the state of Rio Grande do Sul in southern Brazil. Aleodon is unusual among early probainognathians in having transversely-expanded postcanine teeth, similar to those of gomphodont...

In the last decades, several discoveries have uncovered the complexity of mammalian evolution during the Mesozoic Era, including important Gondwanan lineages: the australosphenidans, gondwanatherians, and meridiolestidans (Dryolestoidea). Most often, their presence and diversity is documented by isolated teeth and jaws. Here, we describe a new meri...

Here we describe preliminary results regarding the paleoneurology of a new peirosaurid from the Adamantina Formation, São Paulo, Brazil.

A dearth of Mesozoic-aged, three-dimensional fossils hinders understanding of the origin of the distinctive skull and brain of modern (crown) birds¹. Here we report Navaornis hestiae gen. et sp. nov., an exquisitely preserved fossil species from the Late Cretaceous of Brazil. The skull of Navaornis is toothless and large-eyed, with a vaulted craniu...

Stahleckeria potens is a large kannemeyeriiform dicynodont (3–4 m) recovered from the Dinodontosaurus Assemblage Zone (late Ladinian-early Carnian) of the Santa Maria Supersequence, Rio Grande do Sul, Brazil. Most of the Brazilian specimens come from the Chiniquá region, municipality of São Pedro do Sul, and are deposited in foreign collections. Th...

Rhynchosauria is a group of extinct, exclusively Triassic, terrestrial, and herbivorous archosauromorphs, characterized by a peculiar maxillary‐mandibular apparatus. They reached global distribution during the Carnian, with the Hyperodapedontinae clade. The rhynchosaurian record from South America is included in the Ladinian‐?earliest Carnian Dinod...

The Linha São Luiz Geosite is one of the most remarkable outcrops from the central region of Rio Grande do Sul state, southern Brazil. With more than 20 meters of vertical exposure, the locality preserves records of distinct sedimentary episodes, and one of the richest fossil assemblages known in southern Brazil. After a quarter of a century from t...

Traversodontid cynodonts form one of the most abundant tetrapod clades in continental Triassic beds of southern Brazil, with more than eleven species described. Within this clade, Protuberum cabralense is one of its most bizarre members, characterized by a robustly built skull and the presence of rounded protuberances in the dorsal surface of the r...

The acquisition of the load-bearing dentary–squamosal jaw joint was a key step in mammalian evolution1–5. Although this innovation has received decades of study, questions remain over when and how frequently a mammalian-like skull–jaw contact evolved, hindered by a paucity of three-dimensional data spanning the non-mammaliaform cynodont–mammaliafor...

Traversodontid cynodonts are one of the most abundant and diverse groups of tetrapods in the Triassic assemblages of Brazil. These cynodonts are distributed across four Brazilian Assemblage Zones (AZ), ranging from the late Ladinian to the early Norian. The most taxonomically diverse record comes from the Dinodontosaurus AZ, which has so far yielde...

Tyrannosaurus rex is one of the most popular dinosaurs in the world. It inhabited North America during the late Cretaceous, and a large number of specimens are known from USA. The aim of present contribution is to inquire information about a T. rex skull cast that is exhibited in the Vertebrate Paleontology Hall at the Museo Argentino de Ciencias N...

Investigating the evolutionary trajectory of synapsid sensory and cephalic systems is pivotal for understanding the emergence and diversification of mammals. Recent studies using CT‐scanning to analyze the rostral foramina and maxillary canals morphology in fossilized specimens of probainognathian cynodonts have contributed to clarifying the homolo...

The nasal cavity of living mammals is a unique structural complex among tetrapods, acquired along a series of major morphological transformations that occurred mainly during the Mesozoic Era, within the Synapsida clade. Particularly, non-mammaliaform cynodonts document several morphological changes in the skull, during the Triassic Period, that rep...

The Chañares Formation (Ischigualasto‐Villa Unión Basin) is worldwide known by its exquisitely preserved fossil record of latest Middle‐to‐early Late Triassic tetrapods, including erpetosuchids, “rauisuchians,” proterochampsids, gracilisuchids, dinosauromorphs, pterosauromorphs, kannemeyeriiform dicynodonts, and traversodontid, chiniquodontid and p...

Tarjadia ruthae is a quadrupedal terrestrial pseudosuchian from the Middle-early Upper Triassic of the Chañares Formation, La Rioja Province, Argentina. Originally, this species was identified as an indeterminate archosaur and later as a doswelliid archosauriform based on very fragmentary specimens characterized by the ornamentation of the skull ro...

Body size influences most aspects of an animal's biology, consequently, evolutionary diversification is often accompanied by differentiation of body sizes within a lineage. It is accepted that miniaturization, or the evolution of extremely small body sizes, played a key role in the origin and early evolution of different mammalian characters in non...

Theropods comprise a successful group of mostly predatory dinosaurs with varied growth rates that colonized all continents. Much research has addressed the histology of the Global North’s Mesozoic populations, especially coelurosaurians and allosauroids. However, little has been done to understand the histological patterns of the Gondwanan populati...

LISTADO PRELIMINAR PALEOFAUNÍSTICO DE LA FORMACIÓN RÍO NÍO (EOCENO), TUCUMÁN, ARGENTINA

Neuquensaurus australis es un titanosaurio cuyos restos provienen de la Formación Anacleto (Campaniano superior), en la provincia de Río Negro. Si bien este taxón es conocido hace más de un siglo, hallazgos recientes proporcionaron materiales novedosos, incluyendo, entre otros, dos atlas (MCS-Pv-174/84 y 174/85) y dos axis (MCS-Pv-174/80 y 174/81)....

Las colecciones paleontológicas del Museo Municipal de Ciencias Naturales “Carlos Ameghino” (MCA, Mercedes, Provincia de Buenos Aires, Argentina) se componen principalmente de materiales provenientes de la Formación Luján, que incluyen la Biozona de Equus (Amerhippus) neogaeus y representan al Piso/Edad Lujanense, acotado al Pleistoceno Tardío/inic...

The Serra da Galga Formation is a geological unit that has provided a taxonomically diverse fossil record for the Late Cretaceous of Brazil. The formation highlights the richest evidence of titanosaurs in this country, with a handful of described species, (e.g. Uberabatitan ribeiroi). Over time, palaeobiological works based on the osteohistology of...

Ever since the discovery of the first remains of Macrauchenia patachonica by Charles Darwin in 1834, this taxon has puzzled researchers with its peculiar anatomy. Being the best-known member of the family Macraucheniidae and with fossil records in extensive areas of South America between the Middle to Late Pleistocene/earliest Holocene, M. patachon...

Proterochampsidae is a clade of non-archosaurian archosauriforms restricted to the Middle to the Late Triassic of the Ischigualasto-Villa Unión Basin of Argentina and the Santa Maria Supersequence of Brazil. A reappraisal of proterochampsid specimens from the Brazilian Dinodontosaurus Assemblage Zone (AZ) of the Pinheiros-Chiniquá Sequence (late La...

The Predebon Site, located in São João do Polêsine, Quarta Colônia region (Rio Grande do Sul, Brazil) has a Triassic fauna, including footprints and traces of small vertebrates and abundant remains of rhynchosaurs. This fauna is typical of the Hyperodapedon Assemblage Zone, which is correlated to the late Carnian Ischigualasto Formation (Ischiguala...

Titanosaur sauropods are a common component of the Upper Cretaceous fauna of the Serra da Galga Formation, Triângulo Mineiro region, Minas Gerais, Brazil. Among these, three distinct tooth morphotypes are recognized and described here. One of the teeth represents the largest titanosaur tooth ever found, whereas others correspond to possible juvenil...

Dr. Carlos L. Spegazzini is a renowned scientist in the field of Botany, especially for his herbariums and taxonomic contributions. In the course of his life he named over a thousand species of vascular plants and more than eight hundred species of fungi. Between 1924 and 1926 Spegazzini published three articles on Paleobotany, describing six new s...

La Fundación de Historia Natural Félix de Azara tiene un fondo documental que conserva fotos y archivos de diversos estudiosos de las Ciencias Naturales en Argentina. Recientemente se incorporó a dicho fondo documental una serie de documentos, separatas y libros que pertenecieron al matrimonio Estela Yolanda Santilli - Osvaldo Alfredo Reig y que co...

In this contribution we analyze the origin, organization and activities of the "Sociedad Ameghiniana de Ciencias Naturales e Instituto de Historia Americana" which began in 1947 and existed for more than 10 years. This society had its main headquarters at the Museo Escolar de Ciencias Naturales de San Antonio of San Antonio de Areco. The first dire...

Chiniquodontidae is a family of nonmammaliaform probainognathian cynodonts with occurrences in the Middle to Late Triassic of Africa and South America (Brazil and Argentina). The history of the family is marked by changes in composition and revisions due to the poor preservation of the first discovered specimens. Currently, Chiniquodontidae include...

In this contribution we describe a new genus and species of gomphodontosuchine cynodont from the Late Triassic Hyperodapedon Assemblage Zone (AZ) of the Santa Maria Supersequence of southern Brazil, based on material collected 20 years ago. The new taxon, Santagnathus mariensis gen. et sp. nov., is based on numerous cranial and postcranial remains,...

Protuberum cabralense é um cinodonte traversodontídeo da Zona de Associação (ZA) de Dinodontosaurus (Ladiniano-Carniano) do Rio Grande do Sul, conhecido apenas por um crânio e materiais pós-cranianos associados. Neste trabalho estudamos a cavidade cerebral e aspectos da dentição pós-canina baseados em uma tomografia médica do holótipo MPDC 368-100....

Prozostrodon brasiliensis and Therioherpeton cargnini are non-mammaliaform cynodonts that lived ~233 million years ago (late Carnian, Late Triassic) in western Gondwana. They represent some of the earliest divergent members of the clade Prozostrodontia, which includes "tritheledontids", tritylodontids, "brasilodontids", and mammaliaforms (including...

This contribution includes the analysis of 39 pieces of the Vertebrate Paleontology Collection of the Argentinean Museum of Natural Sciences “Bernardino Rivadavia”. These specimens were acquired before 1925 from the Heidelberger Mineralien-Comptoir company, which was a firm specialized in mineral and fossil commercialization during XIX and beginni...

Two lineages of Kannemeyeriiformes (Synapsida, Dicynodontia) are currently known in the Ladinian–Carnian Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina): stahleckeriine stahleckeriids, based upon postcrania, and a single non-stahleckeriine species, Dinodontosaurus brevirostris, known mostly by cranial material. Available data on the...

Triassic cynodonts from South America are key taxa in the investigation of the emergence of mammalian characters. One of the most iconic species from the Carnian is Prozostrodon brasiliensis, found in Late Triassic strata from southern Brazil. This non-mammaliaform cynodont represents the earliest-diverging member of Prozostrodontia, a clade that e...

The description of new titanosaur specimens unearthed from deposits of the Serra da Galga Formation (Bauru Group, Late Cretaceous) at the BR-262 site, near Peirópolis (Uberaba, Minas Gerais State, Brazil), sheds light on the taxonomy of two taxa previously known from the same area and geological unit: Baurutitan britoi and Trigonosaurus pricei. A c...

The Lohan Cura Formation (Albian) at the Cerro de los Leones locality (Neuquén Province, Patagonia, Argentina) yielded several fossil materials, especially sauropod specimens. Among these, Agustinia ligabuei includes postcranial elements of a single individual, with widely debated taxonomy and phylogeny. Here, we provide an extended osteological de...

Durante mucho tiempo la principal fuente de información sobre mamíferos del Cretácico Superior de Gondwana estuvo dominada por los registros provenientes de la Patagonia argentina y Madagascar, en conjunto con registros más antiguos distribuidos en África continental y Australia. En el registro del Campaniano-Maastrichtiano predominan numerosas esp...

Las asociaciones de vertebrados del Cretácico Superior en altas latitudes de Sudamérica son relevantes para el entendimiento de la evolución y paleobiogeografía de las biotas australes. En particular, los afloramientos de la Formación Dorotea en el Valle del río de Las Chinas, ubicado en la Región de Magallanes, preservan un extenso registro geológ...

Among terrestrial vertebrates, only crown birds (Neornithes) rival mammals in terms of relative brain size and behavioural complexity. Relatedly, the anatomy of the avian central nervous system and associated sensory structures, such as the vestibular system of the inner ear, are highly modified with respect to those of other extant reptile lineage...

In the present paper, we report new anuran remains recovered from strata referred to the Adamantina Formation (Upper Cretaceous) cropping out near Catanduva city, São Paulo, Brazil. The remains represent two individuals, one of which bears a set of peculiar characteristics, both cranial and postcranial, that allows us to assign them to the already...