First record of the tritylodontid cynodont Oligokyphus and cynodont postcranial bones from the McCoy Brook Formation of Nova Scotia, Canada

Abstract

A fragment of a right dentary with one postcanine tooth from the Upper Triassic (Rhaetian) Scots Bay Member of the McCoy Brook Formation at Wasson Bluff, Nova Scotia, Canada, represents the first record of the tritylodontid cynodont Oligokyphus from the early Mesozoic of eastern North America. In addition, three dissociated postcranial bones from the same horizon and locality are referable to derived cynodont therapsids. One of these elements, a nearly complete right humerus, can be assigned to Tritylodontidae. Two other bones, an ulna and incomplete ischium, belong to indeterminate derived cynodonts but show no features allowing more precise taxonomic identification. The presence of Oligokyphus in the McCoy Brook Formation provides additional evidence for the remarkably wide geographic distribution of many latest Triassic and Early Jurassic continental tetrapods.