Dongnanosuchus: The Maoming Alligator
Currently working on the wikipedia page for Dongnanosuchus, so I'm happy to share some new illustrations and of course accompanying info.
Dongnanosuchus is a small crocodilian from the Eocene of China that is assigned to the clade Orientalosuchina. Orientalosuchins are currently poorly understood animals that were possibly endemic to Asia throughout the Cretaceous and Paleogene, tho its not entirely clear how they relate to other crocodilians.
Traditionally, by which I mean the original interpretation from 2019, they are thought to be some early branch of alligatoroid, but some studies have disputed this. One from this year showed that they could be reasonably placed at the base of Longirostres (the croc+gharial clade) and last year a study even had some results recover them as mekosuchines (tho the vast majority of analysis from said study did not recover the same result). Part of the reason for this is that they kinda mix and match features of both crocodyloids and alligatoroids, so future studies will be needed to better clarify all that.
Fossils of Dongnanosuchus are exlusively known from the Chinese Maoming Basin, which during the Eocene represented a lake located in a subtropical environment. In addition to Dongnanosuchus, this region was inhabited by one other crocodilian, the early gavialoid Maomingosuchus. This actually brings up an interesting point.
Tobias Massonne has highlighted that during the Late Eocene, there is an interesting set of co-occurances among Asian crocodilians. Maomingosuchus was found in three major basins: the Krabi Basin in Thailand, the Na Duong Basin in Vietnam and the Maoming Basin in China. Each of these basins was also home to an orientalosuchin. The Krabi was home to Krabisuchus, Na Duong Orientalosuchus and Maoming Dongnanosuchus. So each basin featured its own distinct genus of short-snouted orientalosuchin and a distinct species of the narrow-snouted Maomingosuchus (as shown in Massonne's figure below).
