New mesonychian dentitions from the Paleocene and Eocene of the Bighorn Basin, Wyoming

This paper describes several exceptional mesonychian dental specimens from the late Paleocene-early Eocene Fort Union and Willwood formations of the Bighorn Basin. They include three new species of Dissacus, one of late Tiffanian and two of Wasatchian age, and several virtually complete dentitions of D. praenuntius. Dissacus longaevus lacks diagnostic traits, and is here considered a nomen dubium. Other specimens reported include well-preserved upper and lower dentitions of Pachyaena gigantea, the first nearly complete maxillary dentition of P. gracilis, and a new specimen of the very rare basal Wasatchian Hapalodectes anthracinus. -from Authors