DOI: 10.5061/dryad.6jq5d
title: Data from: Revision of the early crocodylomorph Trialestes romeri (Archosauria, Suchia) from the lower Upper Triassic Ischigualasto Formation of Argentina: one of the oldest-known crocodylomorphs

description: Trialestes romeri (Reig) is an early crocodylomorph from the Ischigualasto
 Formation (late Carnian – early Norian; Ischigualasto – Villa Unión Basin,
 Argentina) and one of the oldest-known members of this clade. Two
 specimens of this species are known, the holotype (PVL 2561) and a
 referred specimen (PVL 3889), both consisting of associated cranial and
 postcranial remains. These specimens are incomplete and poorly preserved
 thus leading previous authors to propose different phylogenetic hypotheses
 for the species. Trialestes romeri was originally interpreted as a basal
 dinosaur, subsequently considered to be a crocodylomorph with some
 dinosaurian characters (e.g. mesotarsal ankle joint, functionally
 tridactyl pes), and even proposed as a chimera representing two different
 genera. Some recent workers have mentioned and discussed Trialestes, but
 none have described it in detail or included it in a quantitative
 phylogenetic analysis. Here, we describe in detail all the material
 assignable to the species and test its phylogenetic relationships using a
 comprehensive data matrix focused on early archosaurs. We support the
 referral of PVL 3889 to Trialestes and reject the presence of a mesotarsal
 ankle joint in this specimen. We recovered Trialestes within
 Crocodylomorpha, closer to Crocodyliformes than Pseudhesperosuchus,
 Hesperosuchus, Dromicosuchus and Sphenosuchus. Several stratigraphical
 units worldwide approximately coeval with the Ischigualasto Formation,
 have also yielded early crocodylomorph remains, such as the upper Santa
 María (Brazil), Pekin (USA), and lower Maleri (India) formations. However,
 the crocodylomorph specimens recovered from those units are more
 incomplete, possess uncertain phylogenetic affinities, or are part of
 chimaerae. Therefore, Trialestes represents the most completely known of
 the earliest non-crocodyliform crocodylomorph taxa known to date.
description: Additional Supporting
 InformationThis file contains four
 appendices: the character list (Appendix S1), the character scorings
 modified from the original data matrix of Zanno et al. (2015) for Carnufex
 carolinensis (Appendix S2), the table of specimens used to build the
 palaeomap of Triassic crocodylomorphs (Fig. 15) (Appendix S3), and the
 references of the Additional Supporting Information (Appendix
 S4).Lecuona
 et al 2016 - Additional Sup.
 Information.pdfData matrix used for the
 analysisThis data matrix is
 based upon a modified version of the data matrix of Lecuona (2013), which
 in turn, was modified from the analysis of Nesbitt (2011). The changes
 proposed by Butler et al. (2014) were also in this data matrix (also
 Lecuona et al. unpub. data). Finally, we added the early crocodylomorph
 Carnufex carolinensis (Zanno et al. 2015, Drymala and Zanno 2016),
 modified scorings for several taxa, and modified the formulation of the
 characters 219 and 241. Three terminals were included for Trialestes, the
 holotype (PVL 2561), the referred specimen (PVL 3889), and the combination
 of both. The final data matrix consists on 87 terminals and 483
 characters.Lecuona et al 2016 - Data
 matrix of the analysis.nex