Timothy J. Gaudin

Timothy J. Gaudin
University of Tennessee at Chattanooga | Chatt · Department of Biological and Environmental Sciences

About

128
Publications
44,976
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,030
Citations

Publications

Publications (128)
Article
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 ph...
Article
New remains of a relatively plesiomorphic nothrotheriid sloth have been recovered from upper Miocene- aged deposits near the village of Achiri in the Altiplano of Bolivia. The new specimens appear allied to other middle and late Miocene remains from Argentina and Bolivia that have been assigned to the pseudo-genus ‘Xyophorus’. ‘Xyophorus’ has not p...
Article
The fossil record for pangolins is sparse. Current biogeographic data suggest this clade originated in Europe, though pangolins seem to have disappeared from the European paleontological record during the middle Miocene, when they were hypothesized to have been pushed toward more tropical and sub-tropical equatorial environments due to global cooli...
Article
Full-text available
The skeletal anatomy of the anterior narial region in mammals is complex, comprised of several bony and cartilaginous elements. Because it includes many cartilaginous components, preservation of this area in extant and extinct specimens is often incomplete. This, along with its complexity, means that this region of the cranium is generally understu...
Chapter
The mammalian order Xenarthra includes the armadillos, sloths and anteaters and the extinct glyptodonts; the mammalian order Pholidota comprises the pangolins or scaly anteaters. Although they were once thought to be closely related, Xenarthra is now generally considered to represent one of the four primary divisions of placental mammals, with pang...
Article
Full-text available
Extinct terrestrial sloths are common elements of the late Cenozoic South American fossil record. Among them, Mylodontinae species were particularly abundant in the Americas throughout the Pleistocene epoch, and their anatomy is relatively well known. In contrast, less information is available from the Neogene record and particularly from localitie...
Article
Full-text available
Pronothrotherium typicum is a late Miocene–early Pliocene (Huayquerian–hapadmalalan 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...
Data
Appendix 1. Digital model of the external cranial morphology of Pronothrotherium typicum (.ply file).
Article
The Early Pleistocene of Eurasia is marked by significant climatic, environmental, and faunal shifts and is the time during which Homo first appears in the Eurasian fossil record. To better characterize the environments that were available to these hominins, accurate data regarding the faunal composition of eastern European sites are necessary, as...
Article
The mammalian sternum plays key roles in structural support, locomotion and ventilation, but its evolutionary history has rarely been addressed. Unlike most other synapsids, the therian presternum lacks a discreet interclavicle, and the mesosternum is composed of a series of sternebrae. Here, CT scans of fossil and living therians are used to confi...
Article
Full-text available
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 tomographi...
Article
Full-text available
The internal cranial morphology of the terrestrial sloth Glossotherium robustum is described here based on a neurocranium from the late Pleistocene of the Pampean region of Buenos Aires, northeastern Argentina. The first published data on the morphology of the brain cavity of this species date back to the latest nineteenth century. The novel techni...
Article
Full-text available
Cranial skeletal material of the Eocene palaeanodont Metacheiromys marshi was examined using high-resolution CT scans. The present study represents the first time that CT scans have been conducted on skulls of this extinct fossorial mammal. The bony osteology of the auditory region is described in detail, including the ectotympanic and entotympanic...
Article
Sexual 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...
Article
Full-text available
The phylogeny of mylodontid sloths has recently been the subject of multiple studies. Contrasting hypotheses have been proposed, especially for the relationships among late Miocene–Pleistocene mylodontines and lestodontines. In this paper, a new and detailed phylogenetic analysis is conducted, after adding new characters and taxa previously unexplo...
Article
Full-text available
Analysis of ontogenetic changes in long bone microstructure aid in vertebrate life history reconstructions. Specifically, osteohistological examination of common fauna can be used to infer growth strategies of biologically uncommon, threatened, or extinct vertebrates. Although nine-banded armadillo biology has been studied extensively, work on grow...
Data
Transverse sections of sampled femora under linearly polarized light. (A) UTCM 802, (B) UTCM 801, (C) OMNH 39188, (D) UTCM 1557, (E) OMNH 40173, and (F) OMNH 40175. All sections are stained with toluidine blue. FL—femur length. Note–some sections were flipped along the horizontal axis to allow for easier comparisons. (TIF)
Data
Transverse sections of sampled tibiae under linearly polarized light. (A) UTCM 802, (B) UTCM 801, (C) OMNH 39188, (D) UTCM 1557, (E) OMNH 40173, (F) OMNH 40175. All sections stained with toluidine blue. TL = tibia length. Note–some sections were flipped along the horizontal axis to allow for easier comparisons. (TIF)
Data
Transverse sections of sampled femora under circularly polarized light. (A) UTCM 802, (B) UTCM 801, (C) OMNH 39188, (D) UTCM 1557, (E) OMNH 40173, and (F) OMNH 40175. All sections are stained with toluidine blue. FL—femur length. Note–some sections were flipped along the horizontal axis to allow for easier comparisons. (TIF)
Data
Transverse sections of sampled tibiae under circularly polarized light. (A) UTCM 802, (B) UTCM 801, (C) OMNH 39188, (D) UTCM 1557, (E) OMNH 40173, (F) OMNH 40175. All sections stained with toluidine blue. TL = tibia length. Note–some sections were flipped along the horizontal axis to allow for easier comparisons. (TIF)
Article
Full-text available
Sexual 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...
Article
Fossil remains of extinct terrestrial sloths have been discovered in numerous localities throughout the Americas, but knowledge of these animals remains poor in the tropical latitudes in comparison with the austral ones. Even where Pliocene mylodontine sloths are known from North and South America, well-preserved craniodental remains are extremely...
Book
This chapter provides an authoritative account of the phylogeny and taxonomy of fossil and extant pangolins. Historical discrepancies around the taxonomy of pangolins are discussed, notably in terms of infraordinal classification, while the respective merits of morphological and molecular analyses to solve the phylogenetic relationships among pango...
Article
Full-text available
To investigate the evolution of xenarthran epaxial muscles, fresh specimens of the North American Common long-nosed armadillo Dasypus novemcinctus and of a marsupial, the Virginia opossum Didelphis virginiana, were dissected. Data from one fixed specimen of a two-toed sloth Choloepus didactylus were also used for comparison, because it is a xenarth...
Article
Full-text available
Fossil remains of extinct terrestrial sloths have been discovered in numerous localities throughout the Americas, but knowledge of these animals remains poor in the tropical latitudes in comparison with the austral ones. Even where Pliocene mylodontine sloths are known from North and South America, well-preserved craniodental remains are extremely...
Conference Paper
Full-text available
El dimorfismo sexual (i.e., la divergencia fenotípica entre machos y hembras de la misma especie) es extremadamente común en las especies con reproducción sexuada y se ha reconocido en muchos linajes mamalianos, actuales y extintos. En los perezosos vivientes, el dimorfismo sexual es poco acentuado, aunque para los representantes extintos constituy...
Conference Paper
Full-text available
Fossil remains of ground sloths have been discovered in numerous localities throughout the Americas, but knowledge of these animals remains poor in the tropical latitudes, in comparison with other extinct folivoran taxa from more northern and southern regions. During the Pliocene, mylodontine ground sloths were spread from North to South America bu...
Conference Paper
Full-text available
The latest CT-scanning facilities and 3D imagery techniques are greatly improving our understanding of animal morphology, revealing important aspects of the internal cranial anatomy for both extant and extinct vertebrates. This non-destructive methodology has the potential to greatly facilitate studies of adaptations and paleobiology for fossil spe...
Article
The monospecific giant anteater, Myrmecophaga tridactyla Linnaeus, 1758, is the largest of the 4 species of New World vermilinguans. A feeding specialist on ants and termites, it occupies a broad range of lowland habitats, from dry scrub and savannah to rainforests. Its geographic range extends throughout southern Central America and northern South...
Article
Full-text available
Several detailed studies of the external morphology of the ear region in extinct sloths have been published in the past few decades, and this anatomical region has proved extremely helpful in elucidating the phylogenetic relationships among the members of this mammalian clade. Few studies of the inner ear anatomy in these peculiar animals were cond...
Article
Full-text available
The present study entails descriptions of several well-preserved skulls from the pampathere species Holmesina floridanus, recovered from Pliocene localities in central Florida and housed in the collections of the Florida Museum of Natural History. Bone by bone descriptions have allowed detailed reconstructions of cranial morphology. Cranial foramin...
Conference Paper
Full-text available
The species Glossotherium robustum (Owen, 1842) was one of the most widespread ground sloths during the Pleistocene of South America, and is one of the most well studied species of the family Mylodontidae. This species was discovered by Charles Darwin during his travels on the HMS Beagle, and subsequently studied by Richard Owen, becoming one of th...
Poster
Full-text available
Analysis of ontogenetic changes in long bone microstructure aid in vertebrate life history reconstructions. Specifically, osteohistological examination of common fauna can be used to infer growth strategies of biologically uncommon, threatened, or extinct vertebrates. Although armadillo biology has been studied extensively, work on growth history i...
Article
A new genus and species of late Pleistocene megalonychid sloth, Nohochichak xibalbahkah, gen. et sp. nov., is described from Hoyo Negro, a chamber in the Sac Actun cave system, Quintana Roo, Mexico. Phylogenetic analysis indicates that this new sloth is most closely related to Meizonyx salvadorensis from the middle Pleistocene of El Salvador, and t...
Article
Full-text available
Smithsonian Contributions to Paleobiology , no. 98, viii+102 pages, frontispiece + 52 figures, 1 appendix with 13 tables, 2016. — Patriomanis americana is the only pangolin (Mammalia, Pholidota), living or extinct, known from the Western Hemisphere. It derives from latest Eocene (Chadronian North American Land Mammal Age) deposits from central Wyom...
Article
Full-text available
In most folivorans, the premaxilla is loosely attached to the maxilla, so that it is often missing in otherwise very well-preserved fossil skulls. Despite its infrequent preservation in sloths, the premaxilla has been shown to have phylogenetically significant variation among the taxa that do preserve the element. In the family Megalonychidae, the...
Article
Full-text available
The Thalassocninae is a monogeneric subfamily of five species of Neogene sloths. Until now, Thalassocnus has been considered as belonging to the Nothrotheriidae, a family of megatherian “ground sloths” of intermediate body size. However, no previous phylogenetic analysis has questioned such a familial attribution. Here we perform an extensive analy...
Conference Paper
Full-text available
Increasing importance has been placed on bone microstructure studies of extant organisms to better interpret the fossil record. For instance, studies examining extant crocodylians, aves, and mammals help describe and interpret extinct tetrapod growth. Nine-banded armadillos (Dasypus novemcinctus) are common taxa throughout the southern United State...