The first North AmericanPropterodon(Hyaenodonta: Hyaenodontidae), a new species from the late Uintan of Utah

Abstract

The carnivorous mammalian fauna from the Uintan (late middle Eocene) of North America remains relatively poorly documented. This is unfortunate, as this is a critical interval in the transition from “creodont” to carnivoran dominated carnivore guilds. This study reports a new species from the Uinta Formation of the Uinta Basin, Utah, the first North American species of the otherwise Asian hyaenodont genus Propterodon. The new species, Propterodon witteri, represented by a dentary with M2-3 from the late Uintan Leota Quarry, is larger than the well-known P. morrisi and P. tongi and has a larger M3 talonid, but is otherwise very similar. A phylogenetic analysis of hyaenodont interrelationships recovers P. witteri as a hyaenodontine but is generally poorly resolved. A relationship between Hyaenodontinae and Oxyaenoides, recovered by many recent analyses, is not supported. Among the Asian species of Propterodon, P. pishigouensis is reidentified as a machaeroidine oxyaenid and recombined as Apataelurus pishigouensis new combination. Isphanatherium ferganensis may also represent an Asian machaeroidine. Identification of a North American species of Propterodon and an Asian Apataelurus increases the similarity of North American Uintan and Asian Irdinmanhan faunas and suggests that there was substantial exchange of carnivorous fauna during the late middle Eocene.

Eomakhaira molossus, A New Saber-Toothed Sparassodont (Metatheria: Thylacosmilinae) from the Early Oligocene (?Tinguirirican) Cachapoal Locality, Andean Main Range, Chile

“…to another saber-toothed clade such as machaeroidine "creodonts" (see Zack, 2019b). Barbourofelid carnivoramorphans first appear in the early Miocene (20-19 Ma; Morales et al, 2001;Morlo et al, 2004) and are last recorded in the late Miocene (6 Ma; Tedford et al, 2004), a range of 13-14 million years.…”

Carnivorous mammals from the middle Eocene Washakie Formation, Wyoming, USA, and their diversity trajectory in a post-warming world

“…Mammalian faunal interchange between North America and other northern continents is generally thought to have been lower during the middle Eocene than in the late Paleocene to early Eocene (Woodburne, 2004; Woodburne et al, 2009). The few carnivores that are thought to have dispersed into or out of North America during the middle Eocene include the mesonychian Harpagolestes (Szalay and Gould, 1966; Jin, 2005), the hyaenodontans Propterodon and Sinopa (Morlo et al, 2014; Zack, 2019b), and the oxyaenid Apataelurus (Zack, 2019b). Late Bridgerian to early Uintan carnivore assemblages of North America in particular are distinct in retaining relictual lineages of carnivoramorphans (e.g., Viverravus , Uintacyon ) that had disappeared earlier from elsewhere in the Holarctic.…”