Reg. Charity No. 1168330
This article presents a detailed description and reconstruction of the palate of Chroniosaurus dongusensis, a chroniosuchid tetrapod from the Upper Permian of Russia, based on a new, chemically prepared specimen representing a juvenile animal with skull length of about 70 mm. It provides new information on this poorly known portion of the skull. The vomer, palatine and ectopterygoid are elongate bones bearing tusks on their lateral margins: six on the vomer, at least nine on the palatine and at least seven on the ectopterygoid. The anterior portion of the vomer is broad and meets its fellow in the median plane. The pterygoid is the largest and longest element of the palate. The anterior end of the pterygoid is divided into a pair of processes; the medial process meets its fellow in the median plane, and the anterior ends of these fit between the vomers. The medial margin of the palatal ramus bears no denticles and the edge is distinctly bevelled, produced into a dorsally inturned flange. The parasphenoid extends anteriorly into a long and narrow cultriform process located between the medial margins of the palatal rami of the pterygoids. The transverse process of the pterygoid is small, but distinct. The ventral surface of the pterygoid bears rows of small denticles that radiate from a site immediately lateral to the articular portion of the pterygoid. The posterior portion of the parasphenoidal plate extends into a short but distinct laterodorsally oriented processes. Using additional data derived from the current study, we performed a cladistic analysis based on an earlier one by the same authors. This analysis recovered 6 most parsimonious trees. The results differed slightly from the previous analysis in that all placed Chroniosaurus below the Viséan and Namurian anthracosaur Eoherpeton at the base of the Embolomeri, a group of Upper Carboniferous stem amniotes, rather than more crownward as in some of the previous trees.