Osteología craneana y taxonomía de Pronothrotherium (xenarthra, folivora, nothrotheriidae) del mioceno tardío–plioceno temprano de la provincia de Catamarca (Argentina)

Pronothrotherium typicum es un perezoso notrotérido del Mioceno tardío–Plioceno temprano (Edades Mamífero Huayqueriense–Chapadmalense) de la provincia de Catamarca, noroeste de Argentina. Pronothrotherium es uno de los cuatro géneros de notroterinos cuyos esqueletos son relativamente completos, pero a diferencia de los otros tres, su anatomía no ha sido formalmente descripta. El presente estudio proporciona las primeras descripciones e ilustraciones de la anatomía craneana de Pronothrotherium, basadas principalmente en un cráneo casi completo de un subadulto y un fragmento de cráneo de un adulto de P. typicum, depositados en las colecciones del Field Museum (Chicago, Illinois, USA). Se provee también una revisión de la diagnosis de P. typicum basada en caracteres craneanos. El cráneo de esta especie muestra una serie de características específicas, como una marcada quilla del vómer en la región nasofaríngea que termina en una protuberancia globosa, que representaría una característica única dentro de los mamíferos. Sobre la base del presente estudio se reconocen dos especies contemporáneas del género Pronothrotherium, P. typicum y P. mirabilis, aunque la segunda es más dudosa. No se acepta la validez de una tercera especie anteriormente descripta, P. figueirasi, que es considerada como sinónimo de P. mirabilis. Este estudio no se propone resolver las relaciones filogenéticas inciertas entre los notroterinos más conocidos Pronothrotherium, Mionothropus (Mioceno tardío) y los dos géneros de Nothrotheriini pleistocenos, Nothrotherium y Nothrotheriops. Sin embargo, esperamos que los datos proporcionados faciliten futuros estudios que abarquen estas cuestiones.Pronothrotherium typicum is a late Miocene–early Pliocene (Huayquerian–Chapadmalalan SALMA) nothrotheriid sloth known from the Catamarca Province of northwestern Argentina. Pronothrotherium is one of four nothrotheriid genera known from relatively complete skeletal material, but unlike the other three, the osteology of Pronothrotherium has not been formally described. The present study provides the first detailed description and illustration of the cranial anatomy of Pronothrotherium, based largely on a nearly complete, subadult skull of P. typicum from the collections of The Field Museum (Chicago, Illinois, USA), as well as a less well-preserved adult skull and isolated mandible from the same collections. A revised cranial diagnosis of P. typicum is provided in the text. The skull of this species shows a number of distinctive features, most notably a peculiar vomerine keel in the nasopharynx, terminating in a swollen knob, that is, as far we know, a unique morphology among mammals. Based on the results of the present study, there appears to be reason to recognize two contemporaneous species of Pronothrotherium, P. typicum and P. mirabilis, although the latter is less well supported. We do not accept the validity of a third described species, P. figueirasi, considering it instead to be synonymous with P. mirabilis. The present study does not resolve the uncertain phylogenetic relationships among the well-preserved nothrotheriine taxa Pronothrotherium, Mionothropus (late Miocene), and the two Pleistocene genera in Nothrotheriini, Nothrotherium and Nothrotheriops. However, we hope that the data provided will facilitate subsequent phylogenetic studies that may resolve these issues.Fil: Gaudin, Timothy J.. University of Tennessee; Estados UnidosFil: Tuckniss, Susan. University of Tennessee; Estados UnidosFil: Boscaini, Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Pujos, François Roger Francis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: De Iuliis, Gerardo. University of Toronto; Canad

Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia

Extinct scelidotheriine sloths are among the most peculiar fossil mammals from South America. In recent decades, the external cranial anatomy of Pleistocene scelidotheres such as Scelidotherium, Catonyx, and Valgipes has been the subject of numerous studies, but their endocranial anatomy remains almost completely unknown. Today, computed tomographic (CT) scanning methodologies permit the exploration of previously inaccessible anatomical areas through a completely non-destructive process. For this reason, we undertook an analysis of the external and internal cranial anatomy of Catonyx tarijensis from the late Pleistocene of the Department of Oruro, in southwestern Bolivia. One particularly well-preserved specimen allowed detailed observation of all the main cranial osteological features, including the ear region and an almost complete hyoid apparatus, previously unknown for this taxon. Moreover, CT-scanning and subsequent elaboration of digital models of this specimen allowed observation of the brain cavity and cranial sinuses, and reconstruction of the trajectory of the main cranial nerves for the first time in an extinct scelidotheriine sloth. Additionally, we recovered the first three-dimensional reconstructions of the nasal cavity and the turbinates of an extinct sloth. In contrast to the usual depiction, the combined information from the external and internal anatomy suggests reduced lingual protrusion in Catonyx tarijensis, or at least a consistently more limited protrusion of the tongue in comparison with other mylodontid sloths such as Glossotherium robustum. The new morphological information recovered from this extinct sloth is compared with the available information for both extant and extinct forms, providing insights in the paleobiology of the extinct species. The present study reveals the importance of applying these novel non-destructive techniques to elucidate the evolutionary history of sloths.Fil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Iurino, Dawid A.. Università degli studi di Roma "La Sapienza"; ItaliaFil: Mamani Quispe, Bernardino. Museo Nacional de Historia Natural de la Paz; BoliviaFil: Andrade Flores, Rubén. Museo Nacional de Historia Natural de la Paz; BoliviaFil: Sardella, Raffaele. Università degli studi di Roma "La Sapienza"; ItaliaFil: Pujos, François Roger Francis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Gaudin, Timothy. University Of Tennessee At Chattanooga; Estados Unido

The dermal armor of mylodontid sloths (Mammalia, Xenarthra) from Cueva del Milodón (Última Esperanza, Chile)

Dermal ossifications (osteoderms, dermal ossicles, osteoscutes) appear independently in various tetrapod lineages. In mammals, however, dermal ossifications are only present in some members of Xenarthra. This clade includes Cingulata (armadillos and their relatives), and Pilosa, including Vermilingua (anteaters) and Folivora (sloths). In extant xenarthrans, osteoderms are invariably present in cingulates whereas they are absent in pilosans. Among extinct sloths, however, a limited number of taxa possessed dermal ossifications. Records of mummified skins of ground sloths bearing osteoderms found in Cueva del Milodón (Southern Chile), with a late Pleistocene age, allowed us to analyze their micro- and macroscopic morphology. The main goal of this study is to closely examine a portion of a mylodontid skin portion using radiography. The arrangement, morphology and internal structure of the ossicles are analyzed and the results are discussed in the context of previous research. The results we obtained indicate that ossicles vary in shape and size, and the integument has four different patterns of arrangement of the ossicles: that is, areas without ossicles, disorganized ossicles, rows, and mosaic areas. The latter has two variants, with clusters of ossicles forming rosettes or stars. Thin sections of the ossicles allowed us to recognize and describe anatomical features of the bone and its mode of growth. Finally, paleobiological and functional considerations of the dermal armor are discussed along with its phylogenetic and chronological implications.Fil: Toledo, Néstor. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento de Paleontología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Pérez, Leandro Martín. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleozoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Lynx remains from the Pleistocene of Valdemino cave (Savona, Northwestern Italy), and the oldest occurrence of Lynx spelaeus (Carnivora, Felidae)

Fossil lynxes are quite common in the Plio-Pleistocene mammal assemblages of Europe. Despite of this abundant record, the phylogeny of the genus Lynx and the relationships among the different recorded species are far from being resolved. The most controversial species of this group is Lynx pardinus spelaeus or Lynx spelaeus according to different scholars, recorded in the Middle and Late Pleistocene of France and Italy. Here, we describe unpublished remains of fossil lynxes from different layers of the Valdemino cave (Middle to Late Pleistocene, Savona, Italy). The reported evidence suggests that the lynx from Valdemino represents probably the most ancient well-documented material of L. spelaeus in Europe further reinforcing the idea of progressive size reduction and acquisition of more trenchant dentition in the European lineages of lynx (L. pardinus and L. spelaeus) during the Middle to Late Pleistocene.Fil: Ghezzo, Elena. University of Florence; ItaliaFil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Institut Català de Paleontologia Miquel Crusafont; EspañaFil: Madurell Malapeira, Joan. Institut Català de Paleontologia Miquel Crusafont; EspañaFil: Rook, Lorenzo. University of Florence; Itali

The origin of the critically endangered Iberian lynx: Speciation, diet and adaptive changes

A new cranial fossil attributable to the species Lynx pardinus (Temminck, 1827) attests to the presence of this felid in the late Early Pleistocene of the Iberian Peninsula. Certain diagnostic features, such as the confluence of the lacerum posterius and anterior condyloid foramina, and the long and lyre-shaped temporal ridges, allow this find to be established as the first occurrence of the Iberian lynx in Europe. The fossil described here was found in the Avenc Marcel cave (Vallirana, Barcelona, Spain) in association with many other Late Villafranchian faunal remains. The combined presence of the bovid genera Capra and Soergelia, and the rodent species Mimomys medasensis and Mimomys tornensis, allows the age of this deposit to be placed at about 1.6-1.7 Ma. Consequently, the appearance of Lynx pardinus is related here to the faunal turnover that occurred between the Middle and Late Villafranchian, considered to be one of the major changes in the European macromammal fauna. Such an early divergence is in accordance with the evolutionary split proposed by both the molecular data and with the glacial-interglacial dynamics that affected the European region during the Early Pleistocene. Under these circumstances, the Iberian lynx could have originated in isolation in the Iberian Peninsula (a recognized southern European refugium for several species), during one or more glacial episodes. In this time period, this species may also have developed a dependence on small-sized animal prey, such as the lagomorphs of the genus Prolagus and Oryctolagus, already widespread throughout the Iberian Peninsula by that point. In the present work, several topics regarding the earliest evolutionary history of Lynx pardinus are discussed. Understanding the events that took place surrounding the origins of this lineage can shed new light on the future conservation of this extremely threatened felid.Fil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Universitat Autònoma de Barcelona; EspañaFil: Madurell Malapeira, Joan. Universitat Autònoma de Barcelona; EspañaFil: Llenas, Manel. Universitat Autònoma de Barcelona; EspañaFil: Martínez Navarro, Bienvenido. Universitat Rovira i Virgili. Institut Català  de Paleoecologia Humana i Evolució Social; Españ

Anatomy, possible sexual dimorphism, and phylogenetic affinities of a new mylodontine sloth from the late Pleistocene of intertropical Brazil

Glossotherium phoenesis sp. nov. from the late Pleistocene of intertropical Brazil is described and compared with Glossotherium robustum and Glossotherium tropicorum. Compared to these two species, the main differences occur in the shape of the nasal region and pterygoids, proportionate narrowing of the skull, length and arrangement of the tooth rows, degree of projection and form of the mandibular symphysis, height at various points along the dentary, and proportions of the radius, among others described. Clear differences in two well-preserved skulls of the new species are interpreted as representing sexual dimorphism, as occurs in other ground sloths such as Paramylodon and Eremotherium. Other notable features are described for osteoderms and for the ontogenetic developments of the mandible and dentition. The new species G. phoenesis appears to be one of the most derived Mylodontidae, sister taxon of G. tropicorum, and closely related to Pleurolestodon.Fil: Cartelle, Cástor. Pontifícia Universidade Católica de Minas Gerais; BrasilFil: De Iuliis, Gerardo. Royal Ontario Museum; Canadá. University of Toronto; CanadáFil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Pujos, François Roger Francis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Reassessing the phylogeny and divergence times of sloths (Mammalia: Pilosa: Folivora), exploring alternative morphological partitioning and dating models

Phylogenetic relationships among sloths (Folivora) have been extensively studied in the past few decades using maximum parsimony approaches. Recently, Bayesian phylogenetic methods also began to be employed for this task, with advances in methods for data partitioning and tip-dating analyses leading to exciting new possibilities in morphological phylogenetics. In this context, we assembled the largest morphological data set ever applied to sloths and reassessed their phylogeny and divergence times, evaluating alternative models of partitioning and dating in a Bayesian framework. The updated phylogeny of sloths is largely in agreement with previous morphological studies, with Bradypus recovered as sister to Eufolivora, the presence of two major sloth clades (Mylodontoidea and Megatherioidea) and Choloepus among Megalonychidae. However, the present study yields some important advances in understanding the relationships of genera with historically unresolved or controversial allocations. The major sloth clades diversified from the Late Eocene to the Early Miocene. Homoplasy-based partition models outperformed anatomical partitioning and unpartitioned analyses, with considerable impacts on topology and posterior probabilities. Estimates obtained using homoplasy-partitioned models with Bayesian analyses were in strong agreement with those of maximum parsimony. We emphasize the importance of model comparison with Bayes factors and the assessment of synapomorphies in Bayesian morphological phylogenetics.Fil: Casali, Daniel M.. Universidade Federal de Minas Gerais; BrasilFil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Gaudin, Timothy J.. University of Tennessee; Estados UnidosFil: Perini, Fernando A.. Universidade Federal de Minas Gerais; Brasi

Morphological disparity and evolutionary rates of cranial and postcranial characters in sloths (Mammalia, Pilosa, Folivora)

Sloth morphological evolution has been widely studied qualitatively, with comparative anatomy and morpho-functional approaches, or through quantitative assessments of morphological variation using morphometrics. Only recently, however, have folivoran morphological disparity and evolutionary rates begun to be evaluated using discrete character data. Nonetheless, patterns of morphological evolution in separate character partitions have not been investigated, neither the relative influence of, on the one hand, phylogeny, and on the other, dietary and locomotory adaptations of sloths. Here we evaluate those patterns using a phylomorphospace approach, quantifying morphological disparity and evolutionary rates, and investigating possible drivers of morphological evolution for cranial and postcranial characters in Folivora. The evolution of the morphology in those partitions is associated with distinct patterns of disparity among clades and ecological groups, even though the two partitions do not differ substantially in overall evolutionary tempo. Historical processes shaped the morphological evolution of sloths more consistently than ecological ones, although changes in postcranial characters also seem to be associated with locomotory adaptations, in which morphological convergences were much more common. We also discuss important methodological trade-offs in investigations of partitioned datasets mostly composed of fossil taxa.Fil: Casali, Daniel M.. Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas; Brasil. Universidade de Sao Paulo; BrasilFil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Gaudin, Timothy J.. University Of Tennessee At Chattanooga; Estados UnidosFil: Perini, Fernando A.. Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas; Brasi

The origin of "El hombre en el Plata": on the birthdate and birthplace of Florentino Ameghino (1853?1911)

Florentino Ameghino was among the most prolific and influential paleontologists of South America. He left a vast body of scientific work, of considerable relevance even today, but also many open questions related to his enigmatic life and personality. One of these obscure aspects has surely been the absence of reliable geographical and chronological information on his birth. For more than a century, the main hypothesis was that Ameghino was born in the city of Luján (Province of Buenos Aires, Argentina) on the 18th of September, 1854. However, recent evidence reveals that Ameghino was undoubtedly born in Moneglia (Liguria, northwestern Italy) on the 19th of September, 1853. The reasons for this prolonged debate may lie in the intentional concealment of this information by Ameghino himself, but also in the ideological exploitation that shaped his persona after his death. This new evidence, far from being merely of passing interest, is here presented and analyzed, allowing new light to be shed on the life, personality, and sociohistorical context of Florentino Ameghino.Florentino Ameghino fue uno de los paleontólogos más prolíficos e influyentes de América del Sur. Dejó una vasta producción científica, de considerable relevancia aún hoy, pero también muchas cuestiones abiertas relacionadas con su enigmática vida y personalidad. Uno de estos aspectos oscuros ha sido seguramente la ausencia de información geográfica y cronológica confiable sobre su nacimiento. Durante más de un siglo la hipótesis principal fue que Ameghino nació en la ciudad de Luján (provincia de Buenos Aires, Argentina) el 18 de septiembre de 1854. Sin embargo, evidencias recientes revelan que Ameghino sin duda nació en Moneglia (Liguria, noroeste Italia) el 19 de septiembre de 1853. Las razones de este prolongado debate pueden estar en el ocultamiento intencionado de esta información por parte del propio Ameghino, pero también en la explotación ideológica que se llevó a cabo sobre su figura tras su muerte. Esta nueva evidencia, lejos de tener un mero valor enciclopédico, se presenta y analiza aquí, permitiendo arrojar nueva luz sobre la vida, la personalidad y el contexto sociohistórico de Florentino Ameghino.Fil: Boscaini, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Peralta Gavensky, Marina. New Model International School; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: De Iuliis, Gerardo. University of Toronto; CanadáFil: Vizcaíno, Sergio Fabián. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

The earliest well-documented occurrence of sexual dimorphism in extinct sloths: evolutionary and palaeoecological insights

International audienceSexual dimorphism (SD) is extremely common in species that have reproductive roles segregated into separate sexes, and it has been recognized in several mammalian lineages, both extant and extinct. Sexual dimorphism is low to moderate in living sloths, but it had a more important role for extinct sloth taxa. The presence of SD in extinct sloths was first suggested at the end of the 19 th century and it is now commonly advocated as a possible explanation of high intraspecific variation in many extinct sloth species. In this paper, we report the presence of SD in Simomylodon uccasamamensis, a Late Miocene to Late Pliocene sloth from the Bolivian Altiplano. We present evidence of SD in the morphology of cranial and postcranial remains, representing the earliest unequivocal occurrence of size-based SD in an extinct sloth species. Differences between sexes are mainly observed in the morphology of the feeding apparatus and general body size. Comparisons with extant large mammals allow us to hypothesize different food selection between the two sexes, with probable divergent habitat use and concomitant niche separation. This, in turn, could have represented an important selective factor for adaptation to environmental changes experienced by the Bolivian Altiplano in Late Neogene times