WHERE DO THALATTOSUCHIANS GO IN THE CROCODYLOMORPH TREE? INTRODUCING THE CROCSUPERMATRIX PROJECT

YOUNG MARK; HASTINGS, A.K.; ANDRADE, M.B.; WILBERG, E.; SMITH, T.J.; FOFFA, D. ; JOHNSON, M.M.; HERRERA, Y.; BRUSATTE STEPHEN

Caparica

Congreso; XVI Annual Meeting of the European Association of Vertebrate Palaeontology; 2018

Here we introduce the CrocSuperMatrix project, a collaborative effort lead by the authors listed herein, to rectify multiple uncertainty issues currently found in the crocodylomorph tree. Thus far, two datasets have been successfully merged, those of Alexander Hastings and Mark Young ? leading to the formation of the H+Y matrix. Currently, three datasets are in the process of being merged. Firstly, the H+Y matrix, the second is a modified version of the Andrade (mA) dataset, while the last is a modified version of the Wilberg (mW) dataset. These datasets have been restructured into the same anatomical order and share the same 20 common anatomical sub-sections. The first issue for the project to investigate is the evolutionary position of Thalattosuchia, a unique clade that thrived during the Jurassic and Early Cretaceous in marine ecosystems. At present our datasets return conflicting positions for Thalattosuchia, with the H+Y matrix finding thalattosuchians to be mesoeucrocodylians basal to Notosuchia + Neosuchia. The mA dataset recovers Thalattosuchia as the sister taxon to Tethysuchia, while the mW dataset has Thalattosuchia as the sister group to Crocodyliformes. This wide range of possible positions for Thalattosuchia, a major crocodylomorph clade, is bizarre at first-glance. However, thalattosuchians evolved a wide-range of osteological, soft-tissue and neuroanatomical adaptations for an aquatic and/or marine existence that clearly unite the clade, but also makes them disparate from all other crocodylomorphs. Our aim is to unite the character-lists from our datasets and use the combined weight of them to rectify this long-standing issue in crocodylomorph systematics.