Elasmobranch (Chondrichthyes) assemblages from the Albian (Lower Cretaceous) of Ukraine

Abstract

Sampling of six horizons of quartz-glauconite sands in Kaniv dislocations in Ukraine yielded more than three thousand vertebrate specimens, including elasmobranch teeth, chimaera dental plates, actinopterygian and sauropsid teeth and bones. Our study represents the first illustrated and detailed description of elasmobranch teeth from Ukrainian Albian deposits since Rogovich (1861), whose specimens were still preserved in the collections of the Kiev National Natural History Museum of National Academy of Sciences of Ukraine. Twenty-three elasmobranch species belonging to eight orders were identified in our samplings and in some of Rogovich's material. This paper provides new data on the systematics of Cretaceous elasmobranchs and assesses the taxonomic status of Rogovich's species. Sampled assemblages include hybodonts, synechodontiforms, hexanchiforms, squaliforms, squatinifroms, orectolobiforms, heterodontiforms and lamniforms. The latter dominate the assemblages, both in terms of species and number of specimens with small odontaspidid species, early pseudoscapanorhynchids and archaeolamnids as well as large carnivorous sharks Cretoxyrhina and Cretolamna. Most importantly, Paraisurus macrorhizus and Cretoxyrhina vraconensis findings indicate a late Albian age for the sampled deposits, which were so far considered Albian–Cenomanian.