Crocodilaemus robustus (*)
Mesoeucrocodylia is the name of the clade that has replaced the paraphyletic group Mesosuchia. The evolved during the Early Jurassic, and continue to the present day.
It was long known that Mesosuchia was an evolutionary grade,, a hypothesis confirmed by the phylogenetic analysis of Benton and Clark, 1988 which demonstrated that Eusuchia (which includes all living crocodilian species) was nested within Mesosuchia. As the authors did not accept paraphyletic groups, Mesoeucrocodylia was erected to replace Mesosuchia.
Several anatomical characteristics differentiate Mesoeucrocodylia from the other crocodylomorph clades. The frontal bones of the skull are fused together into a single compound element, for example. Mesoeucrocodylians possess somewhat of a secondary palate, formed by the posterior extension of sutured palatine bones. The otic aperture of the members of this clade is blocked posteriorly by the squamosal bone.
Cladogram after Larsson and Sues (2007)
Mesoeucrocodylia |--Thalattosuchia `--Metasuchia |--Notosuchia `--+--Sebecia `--Neosuchia |--+--Pholidosauridae | `--Eutretauranosuchus |--Hylaeochampsa |--Mahajangasuchus `--Crocodylia (modern crocodilians)
1. ^ a b Whetstone KN, Whybrow PJ. 1983. A “cursorial” crocodilian from the Triassic of Lesotho (Basutoland), southern Africa. Occasional Papers of the Museum of Natural History. The University of Kansas 106: 1–37.