Polar Records of Chimaeroid Fishes (Holocephali, Chimaeroidei) from the Upper Cretaceous of Eastern Siberia

We describe the discovery of five fragments of chimaeroid tooth plates from the Lower Coniacian deposits (Volviceramus subinvolutus Zone) of the Yangoda River, Krasnoyarsk Krai (Eastern Siberia). The material is identified as the ‘edaphodontid’ Edaphodon sp. and the long-nosed chimaera Harriotta sp. This is the northernmost known locality for Cretaceous chimaeroids in the world (70.5 degrees north), the palaeogeographic position of which in the Coniacian is calculated as 71 degrees north. The new findings show that chimaeroid associations including ‘edaphodontids’ and rhinochimaerids existed in the Late Cretaceous in the polar latitudes of Eastern Siberia as well as in Chukotka (Russian Far East). Moreover, chimaeroid fishes in the terminal Jurassic in Eastern Siberia were already spawning in the polar environment. In the Southern hemisphere, findings of polar chimaeroids are known as early as the Early Cretaceous (Aptian age), and the diversity of polar chimaeroid associations from the Campanian–Maastrichtian of Antarctica (3–4 genera) allow us to expect a greater diversity of polar chimaeroid assemblages in the Northern hemisphere as well.