Baraminic analysis of Crocodylia based on mitochondrial DNA similarity

Crocodiles, alligators, caimans, and gharials are interesting reptiles that are distinctly different from all other reptiles. These animals can be classified into three families within the order Crocodylia: Alligatoridae (alligators and caimans), Crocodylidae (crocodiles), and Gavialidae (gharials). They are characterized by a long snout with sharp teeth, a long tail, sideways-protruding limbs, a thick scaly ectoderm, and a semi-aquatic, carnivorous lifestyle. As such, they belong to an apobaramin, separate from all other animals.

How many kinds belong to Crocodylia? Are all crocodilian species interrelated, or do they possibly make up multiple, similar-looking kinds, like snakes? No hybridization data exists for crocodylians. In this study, the mitochondrial DNA of 19 crocodylians as well as four outliers were aligned, and the species were clustered based on sequence similarity.

The results show a possible split between Alligatoridae and all other crocodylians. This may seem to indicate two crocodilian holobaramins. However, the order of the 37 genes in the mitochondrial  genome has virtually the same order in the 19 crocodylians in the study, which may indicate that they are a united group. Hennigan proposes three crocodilian holobaramins based on morphological cognita. However, an interesting study of crocodylians by Frederico and McLain also found a split between two groups: Alligatoroidea+Crocodyloidea, and Gavialoidea. However, when fossil species from Eusuchia were added, all of these species were found to form a single holobaramin. Thus, it may be possible that post-Flood extinctions caused the holobaramin Crocodylia to fragment into subgroups.