Phylogenetic relationships and divergence timing of Crocodylus based on morphology and the fossil record

Abstract

Maximum parsimony analysis of 164 morphological characters supports the monophyly of crown-genus Crocodylus relative to other extant lineages. Crocodylus cataphractus is the basalmost living species, and monophyletic New World and Indopacific assemblages are supported. The Indian Mugger (Crocodylus palustris) is closely related to the Indopacific assemblage. Most fossils assigned to Crocodylus do not belong to the crown genus. Only one extinct fossil included in the analysis, Crocodylus palaeindicus (= C. sivalensis), falls within the crown-group Crocodylus and is of uncertain affinities within the group; Adams consensus trees draw C. palaeindicus toward the root of non-cataphractus Crocodylus, and the Nile crocodile (C. niloticus) is the sister taxon to the New World assemblage. The oldest fossil diagnostically belonging to the clade is from the Late Miocene, which is congruent with previous protein distance estimates of a Late Tertiary divergence among living species. Fossils and molecules never actually clashed regarding divergence timing, because very different meanings were applied to the name Crocodylus by paleontologists and neontologists.