Marcelo A. Reguero

National University of La Plata | UNLP · Facultad de Ciencias Naturales y Museo

Cenozoic ectothermic continental tetrapods (amphibians and reptiles) have not been documented previously from Antarctica, in contrast to all other continents. Here we report a fossil ilium and an ornamented skull bone that can be attributed to the Recent, South American, anuran family Calyptocephalellidae or helmeted frogs, representing the first m...

Roth’s explorations, the resulting collections many now allocated in La Plata, Zurich, Geneva and Copenhagen, and his significant contributions in geological—especially stratigraphic—and paleontological topics, are a paradigmatic case for the global history of paleontology and for the Swiss migration history in Latin America. His work included the...

La División Paleontología de Vertebrados del Museo de La Plata tiene una historia de cinco décadas de expediciones, colecciones e investigación científica llevadas a cabo en el continente antártico. Se presenta un recorrido desde los comienzos hasta la actualidad.

We describe new Upper Miocene mammalian specimens from the Maimara Formation (Late Miocene to Early Pliocene) exposed at Humahuaca Basin (23°–24°S), northwestern Argentina (NWA), and analyse their taxonomy and relevance for our understanding of the initial stages of the Great American Biotic Interchange (GABI). The stratigraphical and geochronologi...

Roth’s explorations, the resulting collections many now allocated in La Plata, Zurich, Geneva and Copenhagen, and his significant contributions in geological—especially stratigraphic—and paleontological topics, are a paradigmatic case for the global history of paleontology and for the Swiss migration history in Latin America. His work included the...

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...

Trace elements, particularly rare earth elements (REE), are widely used as proxies to reconstruct paleoenvironmental and taphonomic conditions. We traced these elements in fossil penguin bones collected along the Paleogene sequence exposed in Seymour Island (=Isla Marambio) to test them as indicators of the tectonic changes to which this region was...

Abandoned rookeries belonging to any of the Pygoscelis species are very particular taphocoenosis, usually preserved due to the accumulations of bones, pebbles, and guano year after year in the same nesting area, that condense together with other biogenic material and form ornithogenic sediments. The results of the excavation, sieved and analyses of...

The Snow Hill Island Formation (SHIF; late Campanian-early Maastrichtian) crops out in the northeast of the Antarctic Peninsula and constitutes the basal part of the late Campanian-early Maastrichtian sedimentary succession of the James Ross Basin (NG Sequence). Its major exposures occur at the James Ross and Vega islands. Several fossil-bearing lo...

Historia de la exploración marina en el Atlántico Sur.

Interatheres (Interatheriinae; Notoungulata) from the Cerro Boleadoras Formation, north-west of Santa Cruz Province (Argentina) are described here for the first time. Boleatherium praeludium gen. et sp. nov. is described from a partial skeleton and is characterized by a singular combination of exclusive characters (p1 longer than p2, p3 and p4; lin...

Elasmosaurids are among the most frequently recorded marine reptile fossils from the Campanian–Maastrichtian strata of Antarctica. Here, we describe one of the earliest quarried specimens, MLP 82-I-28-1, which is identified as a non-aristonectine elasmosaurid and phylogenetically nested within Weddellonectia. An ancestral states analysis of dorsal...

Protypotherium (Mammalia, Notoungulata, lnteratheriinae) is a well-known and very diverse genus of extinct native ungulates of South America, widely distributed from southern to middle latitudes of Argentina, Chile, and Bolivia. This genus exhibits distinctive species throughout the Miocene to the beginning of the Pliocene that display an interesti...

The fossil record from Cenozoic sediments provides a great deal of information that has direct bearing on the early assembling of modern Patagonian ecosystems. In this synthesis, we revise selected fossil marine and terrestrial records from the last 66 Ma with the aim of understanding major shifts of Patagonian biotas. From the Paleocene to the mid...

Here, we report on two tarsometatarsi assignable to relatively small-sized Eocene Antarctic penguins, housed in the palaeozoological collections of Naturhistoriska riksmuseet, Stockholm. The Priabonian fossils were collected by museum staff during two joined Argentinean and Swedish expeditions from the Submeseta Formation on Seymour Island, Antarct...

Geological studies in the northern sector of the Chaco foreland Basin, Bolivia, yielded new fossils coming from late Oligocene-late Miocene of the Petaca Formation. Few fossil mammals were known from the Subandean Region of Bolivia. We report a partially complete mandible of a hegetotheriid Hegetotheriinae (Notoungulata, Typotheria) from Abapó (Río...

The Mesozoic plate tectonic and paleogeographic history of the final break up of West Gondwana had a profound effect on the distribution of terrestrial vertebrates in South America. As the supercontinent fragmented into a series of large landmasses (South America, Antarctica, Australia, New Zealand, the Indian subcontinent, and Madagascar), particu...

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...

The late Oligocene mammalian fauna of Quebrada Fiera is one of the most diverse of the Deseadan SALMA (South American Land Mammal Age). We describe its endemic xenarthran assemblage, represented by 13 species, consisting of 2 stem sloths and 11 armoured cingulates. The rare folivoran material confirms the presence of Octodontotherium, one of the ea...

New ichthyosaur remains from the Upper Jurassic of Antarctica, recovered from the Ameghino (=Nordenskjöld) Formation are described. These three new specimens represent the first unambiguous records of ichthyosaurs in this continent. Based on the morphology of the humerus, we refer one of the specimens to Ophthalmosauridae, the dominant ichthyosaur...

Elasmosaurids are one of the most abundant fossil marine reptile groups identified from the Upper Cretaceous strata of Antarctica. However, the documented record of intact elasmosaurid skull remains is scarce. In this study, we describe the first non-aristonectine elasmosaurid skeleton from Antarctica that preserves an associated lower jaw. This sp...

The James Ross Basin, at the northern tip of the Antarctic Peninsula, contains a unique Cretaceous-Tertiary sedimentary succession. The Paleogene sequence exposed in Marambio/Seymour Island has resulted highly fossiliferous, and among vertebrates, birds are one of the best represented groups. Fossil avifauna includes penguins, albatrosses, petrels,...

A new Jurassic neopterygian fish is presented on the basis of an almost complete specimen from the early Tithonian (Late Jurassic) Ameghino (=Nordenskjöld) Formation in the Argentine Antarctic Sector (Antarctic Peninsula). The specimen was recovered during the 2019/2020 Antarctic Summer field. Analysis of the new material suggests this is a new spe...

Scientific activity in the Argentine Antarctic Sector has been conducted by the Instituto Antártico Argentino (IAA) since 1951. The Vertebrate Paleontology Research Group (VPRG) comprises several disciplines within the study of vertebrates and incorporates researchers and technicians from different Argentinian institutions. The main objectives of t...

During the last summer 2020 field trip carried out under the Argentine Antarctic Program (IAA-DNA), new geological and palaeontological data of the Maastrichtian López de Bertodano Formation (Upper Cretaceous), James Ross Basin was recovered. This transgressive/regressive sequence is well exposed in the Sandwich Bluff Member of Vega Island and in t...

The current absence of terrestrial mammals in Antarctica contrast with the information from their fossil record, which indicate that this continent, played an outstanding role in mammalian evolution. Paleobiogeographical proxies suggest that West Antarctica probably functioned as an origin center for Australosphenida during the Jurassic. Also as a...

Although knowledge of Mesozoic marine reptiles from Antarctica has improved considerably in recent years, associated and well-preserved skeletal material of these animals remains uncommon. Here we describe a largely complete, closely associated plesiosaur pelvic girdle recovered from the uppermost Cretaceous (Maastrichtian) Sandwich Bluff Member of...

Se describe a Magallanodon baikashkenke gen. et. sp. nov., un nuevo mamífero gondwanaterio del Cretácico tardío de la Región de Magallanes, en el sur de Chile (Valle del Río de Las Chinas, Estancia Cerro Guido, norte de Puerto Natales, Provincia de Última Esperanza). Las capas portadoras se ubican entre los niveles del Campaniano tardío-Maastrichti...

We describe Magallanodon baikashkenke gen. et. sp. nov., a new gondwanatherian mammal from the Late Cretaceous of the Magallanes Region in southern Chile (Río de Las Chinas Valley, Estancia Cerro Guido, north of Puerto Natales city, Última Esperanza Province). The mammal-bearing layer is placed within the Late Campanian-Early Maastrichtian levels o...

Seymour (Marambio) Island: an outstanding example of Antarctic geological heritage - Volume 32 Issue 3 - Kevin A. Hughes, Luis Carcavilla, Alistair Crame, Enrique Díaz-Martínez, David Elliot, Jane Francis, Jerónimo López-Martínez, Marcelo Reguero

A new Paleogene metatherian from locality IAA 1/90, Marambio (Seymour) Island in the Antarctic Peninsula is described. Pujatodon ektopos, gen. et sp. nov., is recognized on the basis of a tiny lower left molar recovered from early Eocene (late Ypresian) levels of the Cucullaea I Allomember, La Meseta Formation. The tooth is characterized by its sma...

An articulated wing belonging to Palaeeudyptes gunnari containing mineralized skin was found in Lutetian (middle Eocene) sediments from Seymour Island, Antarctica. It shows the connective tissues, morphology and density of the feather follicles, and a groove pattern left by the feather calami resting on the skin. Analysis of the preserved surfaces...

El Eoceno de Antártida (Isla Marambio: formaciones La Meseta y Submeseta) alberga un registro fósil excepcional de cetáceos, ya que es uno de los pocos lugares (junto con Perú y Nueva Zelanda) donde se observa la co-ocurrencia de formas stem (“arqueocetos”) y crown (neocetos o cetáceos modernos) de cetáceos. Si bien el registro fósil es fragmentari...

A diferencia del patrimonio paleontológico y arqueológico, la conservación de sitios y secciones geológicas relevantes no ha sido debidamente reconocida. La Antártida posee valores geológicos y geomorfológicos de gran importancia que es necesario preservar, por ejemplo, de la presencia humana, aún escasa pero de creciente impacto negativo.

Recientemente, la colecta de nuevos elasmosáuridos antárticos ha incrementado el conocimiento del grupo. Sin embargo, también es relevante la redescripción de ejemplares históricos, tales como el MLP 82-I-28-1. Este espécimen procede la Isla Marambio (= Seymour), Formación López de Bertodano (Maastrichtiano–Daniano) y fue, a principios de la década...

Los registros de ictiosaurios hallados en Antártida son escasos, encontrándose únicamente tres referencias en la literatura. Las dos primeras mencionan la presencia de una mandíbula de ictiosaurio hallada en las inmediaciones de Longing Gap, sin figurar ni describir el material. El reporte más reciente está basado en el molde de un diente parcialme...

The fossil record of terrestrial mammals in Antarctica is temporally and geographically constrained to the Eocene outcrops of La Meseta and Submeseta formations in Seymour (Marambio) Island in West Antarctica. The faunal assemblage indicates a clear South American imprint since all the groups have a close phylogenetic relationship with Cretaceous a...

Antarctica has significant environmental, scientific, historic, and intrinsic values, all of which are worth protecting into the future. This continent has a discrete number of places of scientific interest that exhibit great potential as natural heritage sites; its geodiversity is of fundamental importance to scientific values of the continent, an...

Antarctica has significant environmental, scientific, historic and intrinsic values, all of which are worth protecting into the future. West Antarctica has a discrete number of places of scientific interest that exhibit great potential as natural heritage sites, its geodiversity is of fundamental importance to scientific values of the continent, and t...

Associated penguin remains found in Bartonian levels of the Submeseta Formation (Seymour Island, Antarctica), including cranium and mandible, both partial tarsometatarsi, and some other fragmentary bones, are here analyzed. This specimen preserves the first cranium reliably assigned to the giant form Anthropornis grandis, and constitutes the first...

The living tree sloths Choloepus and Bradypus are the only remaining members of Folivora, a major xenarthran radiation that occupied a wide range of habitats in many parts of the western hemisphere during the Cenozoic, including both continents and the West Indies. Ancient DNA evidence has played only a minor role in folivoran systematics, as most...

During the Antarctic summer campaigns and as a result of paleontological fieldworks 2013–2015 several mosasaur remains have been collected from the upper Maastrichtian López de Bertodano Formation exposed at Marambio (=Seymour) Island, of the Antarctic Peninsula. One of these specimens preserves part of the skull and dentition, which represent one...

A detailed histological study of Antarctopelta oliveroi, from the Upper Cretaceous of Antarctica, is performed in order to increase our knowledge of the ankylosaur bone histology and its taxonomical and paleobiological implications. The main goals of this contribution are: to infer the ontogenetic stage of the holotype of Antarctopelta oliveroi (ML...

The Eocene-Oligocene Southern Ocean is thought to have played a major role in cetacean evolution. Yet, fossils from its heart-Antarctica-are rare, and come almost exclusively from the Eocene La Meseta and Submeseta formations of Marambio (Seymour) Island. Here, we provide a summary and update of this crucial fossil assemblage, and discuss its relev...

The Maastrichtian–Danian López de Bertodano Formation comprises a thick sequence of marine deposits that is well exposed on Seymour (= Marambio) and Vega islands. The López de Bertodano Formation yielded vertebrates such as chondrichthyans, teleosts, marine reptiles (plesiosaurs and mosasaurs) and dinosaurs (including birds). On the last three Anta...

Antarctica’s geodiversity is of fundamental importance to the environmental, scientific, wilderness and aesthetic values of this continent, and the pursuit of geological knowledge has had a strong influence on its historical values. Outside the Antarctic Treaty area, geological and paleontological values can be protected under national legislation, o...

La presente contribución se centra en la histología ósea de dos ornitópodos antárticos de la Formación Snow Hill Island (Maastrichtiano-Campaniano), Trinisaura santamartaensis y Morrosaurus antarcticus. El objetivo es establecer el estadio ontogenético de ambos taxones, así como determinar si su crecimiento presenta diferencias significativas con f...

El tejido óseo es una estructura dinámica, capaz de adaptarse a estímulos mecánicos y reparación de daños estructurales mediante el proceso de remodelación. Éste tejido responde a las condiciones mecánicas a lo largo del tiempo. El hueso cambia su forma y su arquitectura interna en respuesta al estrés que actúa sobre él. Con el objetivo de analizar...

Aristonectines show a highly derived morphology among elasmosaurid plesiosaurs, including some species with large body size. A new postcranial skeleton is described from the uppermost Maastrichtian levels of the López de Bertodano Formation, Seymour Island (= Marambio), Antarctica, being referred to as cf. Aristonectes sp; the most striking feature...

Modern baleen whales (Mysticeti), the largest animals on Earth, arose from small ancestors around 36.4 million years ago (Ma). True gigantism is thought to have arisen late in mysticete history, with species exceeding 10 m unknown prior to 8 Ma. This view is challenged by new fossils from Seymour Island (Isla Marambio), Antarctica, which suggest th...

We describe infectious arthritis and spondyloarthropathy in a juvenile mosasaur recovered from the upper Maastrichtian of Antarctica, representing the first report of a skeletal pathology of a mosasaur from the southern hemisphere. Macroscopic examination of the scapula revealed a remodelled, deeply excavated and expanded gleno-humeral joint with a...

We describe osteichthyan remains from the Upper Jurassic of the Ameghino (= Nordenskjöld) Formation of the Antarctic Peninsula. The fossils are referred to a suspension-feeding pachycormid based on the shape, morphology, and presence of acus fanunculi (needle teeth) on their gill rakers. Due to the fragmentary condition of the Antarctic material, w...

Eocene deposits of the famous La Meseta Formation of Seymour Island, Antarctic Peninsula, yielded the most diverse Paleogene fossil elasmobranch association of the Southern Hemisphere. In this assemblage, sharks clearly dominate the fauna, whereas batoids are very rare components. Herein, we describe two new taxa of cold water tolerant skates, Mara...

The last twenty million years (Maastrichtian-Santonian) of Southern Hemisphere plesiosaur history is especially well recorded in the Weddellian Province (Patagonia; Western Antarctica and New Zealand). The oldest Late Cretaceous plesiosaurs, two specimens referred to Polycotylidae indet., come from the Santonian levels of the Santa Marta Formation,...

Early to Late Eocene bryozoans from the La Meseta Formation of Seymour Island were collected at two localities within the Cucullaea I Allomember (Telm4 and Telm5) on the northwestern side of the island and in two localities within the Submeseta Allomember (Telm6 and Telm7) on the northeastern side. This fauna is represented by cyclostomes of the su...

Few fossil mammals were known from the Subandean zone or adjoining parts of Bolivia until recently. We report a partial mandible of Prohegetotherium (YPFB-LIT-PAL-002) from the outcrops of the Petaca Fm, in the Río Grande River (19°1’17” S - 63°33’25” W) near the town of Abapó, in the southwest of the department of Santa Cruz (Bolivia). This specim...

The first record of one of the most common and widespread Paleogene selachians, the sand tiger shark Brachycarcharias, in the Ypresian strata of the La Meseta Formation, Seymour Island, Antarctica, is provided herein. Selachians from the early Eocene horizons of this deposit represent the southernmost Paleogene occurrences in the fossil record, and...

Elasmosaurids are a monophyletic group of cosmopolitan plesiosaurs with extremely long necks. Although abundant elasmosaurid material has been collected from the Upper Cretaceous of Antarctica, skull material is extremely rare. Here, new elasmosaurid cranial material from the lower Maastrichtian levels of the Cape Lamb Member (Snow Hill Island Form...

The first collections of Interatheriinae (Interatheriidae, Notoungulata) were created by the brothers Florentino and Carlos Ameghino, based on fossil specimens collected from diverse outcrops of Argentina and housed at different national institutions. In order to perform a systematic study of the subfamily, it is essential to revise as much specime...

Protecting Antarctica’s geological heritage - Volume 30 Issue 1 - Chris J. Carson, Cliff B. Atkins, Kevin A. Hughes, Marcelo A. Reguero