Revisão sistemática de Gavialoidea (Eusuchia: Crocodylia)

Abstract

Crocodylia is a clade that comprises species such as alligators, caimans, crocodiles, tomistoma and the gharial. Recent studies have proposed a major dichotomy ithin Crocodylia: Brevirostres and Longirostres. Brevirostres are those that derive from an ancestor with a short rostrum (although some longirostrine forms derive within this clade, e.g., the genus Mecistops), while Longirostres are those that derive from an ancestor with an elongated rostrum. The present study reevaluates the phylogeny of these Longirostres clade (Gavialodiea, “Thoracosaurinae” and Tomistominae). Morphological and molecular analyses have shown divergent results regarding the position of these longirostres species among crocodilians, and considering Longirostres, their internal relationships are also unclear. The lack of homologous characters of the postcranium, combined with the lack of illustrations of existing homologues and the misinterpretation of such characters may result in biased data; it is essential to review these homologues, together with their respective illustrations, to facilitate coding in future studies. In the present work, 48 species of the Longirostres clade were studied and 155 morphological homologous characters were analyzed with the addition of each of their respective illustrations. The final phylogenetic tree contains 45 species, and, in it, it was possible to verify the clear division that exists between Tomistominae and Gavialoidea, with Gavialoidea being separated into two large groups (Gavialinae and Gryposuchinae), while Tomistominae presented the formation of four large clades that require further studies for their definitive validation.