Cranial anatomy of a new crocodyliform (Archosauria: Crocodylomorpha) from the Lower Cretaceous of Song-Liao Plain, northeastern China

摘要

Rugosuchus nonganensis, a new genus and species of crocodyliform, is erected on the basis of its peculiar cranial features. This late Early Cretaceous species represents the second, and most complete, crocodyliform known from northeastern China. Its discovery is significant for our understanding of both the local vertebrate fauna and its stratigraphical correlations, and the paleobiogeography of the Crocodyliformes. The palatine contribution to the anterior border of the choana excludes the new form from the Eusuchia, and evidence from osteoderms (not detailed in the present paper) suggests that the new form appears to be phylogenetically closer to the Eusuchia than to the Goniopholididae. Therefore, comparisons are made primarily with those taxa which have a closer relationship to the former than the latter. The unsculpted, depressed, and lobe-like posterolateral process of the squamosal is further demonstrated to be ontogenetically variable and thus inappropriate for use as a character in phylogenetic analyses.