An Early Triassic Ichthyopterygian Fossil from the Osawa Formation in Minamisanriku Town, Miyagi Prefecture, Japan

Abstract

The ichthyopterygian Utatsusaurus hataii Shikama et al. 1978 is the only valid reptilian taxon known from the Lower Triassic Osawa Formation in Minamisanriku Town, Miyagi Prefecture, which records the recovery of the marine ecosystem shortly after the end-Permian mass extinction. In this paper, we describe a fragmentary specimen of an indeterminate ichthyopterygian which is distinguished from Utatsusaurus hataii based on rib morphology. The discovery of a previously unknown ichthyopterygian implies that the taxonomic diversity of the reptilian fauna of this formation is higher than previously assumed.