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The Litopterna is an extinct clade of endemic South American ungulates that range from Paleocene up to late Pleistocene times. Because of their unique anatomy, litopterns are of uncertain phylogenetic affinities. However, some nineteenth century authors, considered litopterns as related to perissodactyl ungulates, a hypothesis recently sustained by molecular data. The aim of the present contribution is to include litopterns and other South American related taxa in a comprehensive phylogenetic analysis together with several extant and extinct basal perissodactyl ungulates. The analysis resulted in the nesting of litopterns and kin as successive stem-clades of crown Perissodactyla. Further, litopterns are not phylogenetically grouped with any North American basal ungulate, in agreement with some previous proposals. Presence of pan-perissodactyls in South America and India indicates that southern continents probably played an important role in the early evolution of hoofed mammals. [ABSTRACT FROM AUTHOR]

Nyctitheriidae is a diverse group of small, insectivorous mammals from the Paleogene of Asia, North America, and Europe that have alternately been linked to Eulipotyphla (shrews, moles, hedgehogs, solenodons), Euarchonta (primates, tree shrews, dermopterans), or Chiroptera (bats). Even intrafamilial relationships are poorly understood, resulting in ambiguity regarding morphological character polarity critical for evaluating supraordinal relationships and paleobiogeographic patterns. To help address this issue, we performed a cladistic analysis of 51 North American, European, and Asian nyctitheriid species, including a new nyctitheriid, Plagioctenodon thewisseni sp. nov. from the late Paleocene of Wyoming, using 66 characters derived from dental morphology. Although the oldest nyctitheriids are found in North America, the resulting most-parsimonious cladograms support an Asian origin of the family with dispersal into North America by the early Paleocene. Among North American and European groups, the subfamilies Nyctitheriinae and Amphidozotheriinae, and the genera Leptacodon and Saturninia are not monophyletic and require future study and revision. The multi-species genera Nyctitherium, Plagioctenodon (including P. thewisseni), Plagioctenoides, Cryptotopos, and Euronyctia are found to be monophyletic, whereas Wyonycteris is paraphyletic, having Pontifactor bestiola nested within it. The earliest known European nyctitheriids ( Leptacodon nascimentoi, Placentidens lotus, Plagioctenodon dormaalensis, Wyonycteris richardi) appear in the early Eocene and are each found in an otherwise strictly North American clade consisting of either solely Paleocene or a combination of Paleocene and Eocene taxa, suggesting at least four earliest Eocene dispersals between North America and Europe. [ABSTRACT FROM AUTHOR]

In this study, I investigated the source(s) of variation in the body temperatures of mammals. I also attempted to reconstruct ancestral normothermic rest-phase body temperature states using a maximum parsimony approach. Body temperature at the familial level is not correlated with body mass. For small mammals, except the Macroscelidae, previously identified correlates, such as climate adaptation and zoogeography explained some, but not all, T apomorphies. At the species level in large cursorial mammals, there was a significant correlation between body temperature and the ratio between metatarsal length and femur length, the proxy for stride length and cursoriality. With the exception of two primate families, all supraendothermic ( T > 37.9°C) mammals are cursorial, including Artiodactyla, Lagomorpha, some large Rodentia, and Carnivora. The ruminant supraendothermic cursorial pulse is putatively associated with global cooling and vegetation changes following the Paleocene-Eocene Thermal Maximum. Reconstructed ancestral body temperatures were highly unrealistic deep within the mammalian phylogeny because of the lack of fossil T data that effectively creates ghost lineages. However, it is anticipated that the method of estimating body temperature from the abundance of C-O bonds in the carbonate component of tooth bioapatite in both extant and extinct animals may be a very promising tool for estimating the T of extinct mammals. Fossil T data are essential for discerning derived T reversals from ancestral states, and verifying the dates of supraendothermic pulses. [ABSTRACT FROM AUTHOR]