Eudaemonema webbi sp. nov. (Mammalia, Mixodectidae) from the late Paleocene of western Canada: the youngest known mixodectid

Abstract

Mixodectidae (Mammalia, Archonta) are an unusual, poorly known family of dermopteran-like mammals that have been discovered at several North American localities of primarily early Paleocene age. Among the three or four recognized mixodectid genera, Eudaemonema Simpson is perhaps one of the least understood, being known from only a few localities of late Torrejonian and earliest Tiffanian age. This paper reports on a new species of Eudaemonema from the late Paleocene of Alberta, Canada, that significantly extends the geographic and stratigraphic ranges of the genus. Eudaemonema webbi sp. nov. is known from middle and late Tiffanian localities in central and south central Alberta, and it represents the youngest and northernmost species of Eudaemonema so far discovered. E. webbi differs from the genotypic species E. cuspidata in being larger and in having a suite of dental characters (e.g., molariform posterior premolars, enlarged molar protocone and hypocone, development of a second grinding platform on the lower molars) that suggests an increased emphasis on grinding during mastication. E. webbi possesses several dental features (e.g., broad, shelf-like molar paraconid–paracristid, lingually shifted molar hypoconulid) that resemble those of cynocephalids (Mammalia, Dermoptera), with these resemblances interpreted herein as convergent. The occurrence of E. webbi at Gao Mine extends the stratigraphic range of Eudaemonema into the late Tiffanian (Ti5) and represents the youngest known record of Mixodectidae.