The phylogenetic revision of Mesoeucrocodylia: basal radiation and major issues

Author(s)

Felipe Chinaglia Montefeltro

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2013-04-09

Examining board members

Max Cardoso Langer; Douglas Riff Gonçalves; Milton Groppo Junior; Alexander Wilhelm Armin Kellner; Jonathas de Souza Bittencourt Rodrigues

• Advisor: Max Cardoso Langer

Abstract

Mesoeucrocodylia is a well established clade encompassing the greatest taxonomic and morphological diversity within Crocodyliformes. However, its basal phylogeny remains poorly understood. Previous works highly disagree on the relationships and validity of an array of basal mesoeucrocodylian groups, particularly Thalattosuchia, Sebecosuchia, Notosuchia, Peirosauridae and Trematochampsidae. The Mesoeucrocodylia basal phylogeny was critically revaluated based on a broad revision. Taxa belonging to the aforementioned subgroups, as well as taxa assigned to other Mesoeucrocodylia major lineages and its immediate outgroups were reanalyzed. Characters previously proposed within this context were also revised and new characters added to cover the morphological diversity within the selected taxa. The final matrix is 122 taxa and 494 character and the parsimony analyses was performed in TNT (5000 RAS, TBR and Hold 20). The strict consensus of the 3575 most parsimonious trees (MPTs) does not fully agree to any of the previous phylogenies. The new analysis depicts a mix of known clades and relationships proposed for the first time. Thalattosuchia is the basal most Mesoeucrocodylia and sister group of Metasuchia. Metasuchia is formed by a dichotomy including Neosuchia on one branch and Gondwanasuchia on the other. Stomatosuchidae is the basal most Neosuchia, followed by Atoposauridae as the sister group of a polytomy encompassing Tethysuchia, Goniopholididae, Bernissartia and a clade of derived neosuchians (Paralligatoridae, Susisuchus and Eusuchians). Gondwanasuchia is formed by a basal polytomy including Doratodon, Peirosauridae + Trematochampsidae, Sebecidae + Mahajangasuchidae and Notosuchia. In this sense, Sebecosuchia was not depicted as a monophyletic group and Baurusuchidae was placed derived in the Notosuchia clade. In addition, Sebecia, as original, conceived was not recovered in all of the MPTs however it is a possible result among the MPTs. (AU)