Alfredo Eduardo Zurita

Several fossil records of the Rheidae family have been recorded from Palaeogene and Neogene deposits (Mayr, 2009; Picasso et al., 2022; Widrig & Field, 2022). Rheas, along with cassowaries, emus, k...

Hydrochoerus hydrochaeris is the largest extant rodent in the world. It is an iconic mammal of the tropical and subtropical wetlands of South America, with significant importance in the ecosystems of northeastern Argentina. Although several diseases affecting capybaras in wild and in captivity have been reported—mainly of bacterial, metabolic, parasitic, and viral origin—bone pathologies remain undocumented. This study presents a macroscopic and radiological analysis of skeletal lesions observed in a road-killed capybara from Corrientes Province, Argentina. The specimen exhibited a marked lesion on the left hemimandible consistent with osteomyelitis, an acute infectious process of nonspecific origin. Extensive bone proliferation was also observed on the humerus, interpreted as enthesic origin, based on its association with forelimb musculature. Additionally, vertebral and tibial lesions were identified and attributed primarily to the individual’s age, consistent with osteoarthritis and osteochondritis dissecans probably the result of subchondral fracture-induced vascular compromise. To our knowledge, this is the first report of these bone pathologies in H. hydrochaeris and underscores the value of systematic examination of carcasses to improve understanding of the health status of wild capybara populations.

Glyptotherium cylindricum (Xenarthra, Glyptodontidae) in the Transvolcanic Belt, State of Puebla, Mexico. Glyptodontinae, was the unique subclades of Glyptodontidae (Cingulata, Xenarthra) that participated in the Great American Biotic Interchange (GABI) and arrived in Central and North America in the early Pliocene (ca. 3.9 Ma). Currently, Glyptotherium is the only one genus recognized in North and Central America, with two chronospecies, Gl. texanum (Late Pliocene–Early Pleistocene) and Gl. cylindricum (Late Pleistocene). While the evolutionary history of this genus has been relatively well studied in the present territory of the United States, little is known about these glyptodonts in southern North America (Mexico) and Central America. Glyptotherium is probably the only pan-American genus of glyptodonts with records in North and Central America and, possibly, northern and western South America. Here, we describe a specimen assignable to Glyptotherium (dorsal carapace, caudal armor, mandible, and vertebrae) and coming from the Late Pleistocene of General Felipe Ángeles Municipality, Puebla (Mexico). In addition, the dorsal profile of the dorsal carapace and its ornamentation pattern allow its assignment to Gl. cylindricum. The location of this new record of Gl. cylindricum allows us to hypothesize that these animals may have used the Trans-Mexican Volcanic Belt-Sierra Madre del Sur axis as a corridor to disperse throughout south-central North America and Central America, especially during the coldest periods of the Late Pleistocene. During this period, both the South American species Glyptodon reticulatus and Gl. cylindricum reached their greatest latitudinal distribution, suggesting an ecological plasticity not observed in other Glyptodontidae throughout their extensive evolutionary history. Keywords: diversity, Pleistocene, distribution, Southern North America.

Within Xenarthra (Eocene‐Recent), Folivora developed (late Eocene‐Recent) a remarkable diversity with respect to ecology and taxonomy over its evolutionary history. Knowledge of the diversity achieved by members of this clade in high‐altitude areas of South America (i.e., Altiplano and Puna regions of Peru, Bolivia, and northwestern Argentina) has been improved in recent decades. A particular example involves the late Neogene Mylodontidae Simomylodon uccasamamensis, known mostly from multiple specimens recovered from the Bolivian Altiplano. Although several anatomical descriptions of this ground sloth have been published, almost nothing is known about its ontogenetic development and the associated morphological changes. Here we describe and compare new specimens of S. uccasamamensis from the upper level of the Tafna Formation (Pliocene) in the eastern Puna (ca. 3800 masl), Argentina, representing the southernmost record of this species. The new material is represented by specimens showing different ontogenetic stages, from infant to adult. One subadult specimen reached an estimated body mass of ca. 232 kg. The comparative study of external and internal morphology (the latter obtained from CT scans and radiography) shows remarkable changes in the mandible and molariforms associated with ontogeny; in addition, evidence suggests that the mfs2‐3 are the first functional teeth, followed by mf1 and cf1. Based on our body mass estimates (ca. 232 kg.), we inferred an average lifespan of 14 years, 9‐month gestation time, and sexual maturation at 4.1 years, quite similar to the values we obtained based on estimated body masses of adult specimens from Bolivia published by previous authors. Along its latitudinal distribution (ca. 14° S‐21° S) S. uccasamamensis co‐occurred with other ground sloths (e.g., Megatheriinae, Thalassocninae, and Scelidotheriinae), suggesting niche partitioning. The presence of this medium‐sized ground sloth is consistent with the similarity between the faunas of eastern Puna and the Bolivian Altiplano during the Pliocene, which is also concordant with what was observed in other clades, such as Rodentia and Notoungulata.