DOI: 10.5061/dryad.61s1n
title: Data from: Morphological and biomechanical disparity of crocodile-line archosaurs following the end-Triassic extinction

description: Mesozoic crurotarsans exhibited diverse morphologies and feeding modes,
 representing considerable ecological diversity, yet macroevolutionary
 patterns remain unexplored. Here we employ a unique combination of
 morphological and biomechanical disparity metrics to quantify the
 ecological diversity and trophic radiations of Mesozoic crurotarsans,
 using the mandible as a morpho-functional proxy. We recover three major
 trends. First, the diverse assemblage of Late Triassic crurotarsans was
 morphologically and biomechanically disparate, implying high levels of
 ecological variation; but, following the end-Triassic extinction,
 disparity declined. Second, the Jurassic radiation of marine
 thalattosuchians resulted in very low morphological disparity but moderate
 variation in jaw biomechanics, highlighting a hydrodynamic constraint on
 mandibular form. Third, during the Cretaceous terrestrial radiations of
 neosuchians and notosuchians, mandibular morphological variation increased
 considerably. By the Late Cretaceous, crocodylomorphs evolved a range of
 morphologies equaling Late Triassic crurotarsans. In contrast,
 biomechanical disparity in the Cretaceous did not increase, essentially
 decoupling from morphology. This enigmatic result could be attributed to
 biomechanical evolution in other anatomical regions (e.g. cranium,
 dentition or postcranium), possibly releasing the mandible from selective
 pressures. Overall, our analyses reveal a complex relationship between
 morphological and biomechanical disparity in Mesozoic crurotarsans that
 culminated in specialized feeding ecologies and associated lifestyles.
description: Stubbs et al.
 Morphological analysis - Raw Landmark DataThis is a tps. file
 containing 2-D digitized landmarks for the mandibles (lower jaws) of 107
 Mesozoic crurotarsans, in lateral view. The file describes the landmark
 coordinates for all 74 landmark points taken on each specimen. Together
 with the associated NTS. sliders file this is used to compute aligned,
 Procrustes transformed, coordinates. The file can be read by notepad, PAST
 and a number of geometric morphometrics software packages, including tps
 software, MorphoJ, or IMP software.Stubbs et al.
 Morphological analysis - Semi-Landmark Data (sliders
 file)This simple NTS. file
 describes which of the 74 landmarks used in this study are sliding
 (semi-landmarks). The file is required to compute aligned, Procrustes
 transformed, coordinates; together with the associated raw landmark data
 file. The file was created in TPSUTIL. To create aligned coordinates both
 this file and the raw landmark data should be input in TPSRELW using the
 chord – min d2 sliding method.Stubbs et al.
 Morphological analysis - Procrustes Aligned CoordinatesThis data file contains
 the Procrustes transformed aligned 2-D landmark coordinates for 107
 Mesozoic crurotarsan mandibles. The file contains taxonomic labels in the
 first column. The file can be opened in PAST (Palaeontological
 Statistics). Using the PCA function on all the data will produce a 2-D
 lateral lower jaw morphospace for Mesozoic
 crurotarsans.Stubbs et al.
 Morphological analysis - PCA axes 1-15File contains 15 PC
 scores from the principal component analysis on the Procrustes transformed
 aligned landmarks. Plotting axes 1 and 2 as an XY plot produces a 2-D
 lateral mandibular morphospace for Mesozoic crurotarsans. In our main
 analyses the first 10 axes were used to calculate morphological disparity,
 together with binary occurrence and groups files using the MDA add-on for
 MATLAB. Data regarding the stratigraphic occurrences and groupings for
 each taxon can be found in the electronic supplementary material
 accompanying our article (Table S1).Stubbs et al.
 Biomechanical analysis - Raw biomehanical character dataThis file contains the
 raw data from 14 biomechanical measurements, taken from the mandibles of
 107 Mesozoic crurotarsans. To produce a biomechanical morphospace the data
 should be z-transformed and entered into PAST. Using the PCO (principle
 coordinates) function and the Gower similarity index will produce a
 biomechanical mandibular morphospace. Abbreviations for characters: Total
 mandibular length (TOTL), Quadrate/articular offset (QUADOFF), Relative
 length of the mandibular symphysis (SYMPH), Relative length of dental row
 (%DENT), Relative area of the fenestrae (%FEN), Anterior mechanical
 advantage (AMA), Posterior Mechanical Advantage (PMA), Opening mechanical
 advantage (OMA), Maximum Second Moment of Area (MAXI), Average Second
 Moment of Area (AVRI), Max polar moment of inertia (MAXJ), Average polar
 moment of inertia (AVRJ), Slenderness of the largest tooth (CUSPMAX), The
 curvature of largest tooth (CURVEMAX). Full descriptions of each character
 can be found in the electronic supplementary material accompanying the
 main article.Stubbs et al.
 Biomechanical analysis - PCO axes 1-15File contains 15 PC
 scores from a principal coordinates analysis of the z-transformed
 biomechanical data, from 107 Mesozoic crurotarsan mandibles. Plotting axes
 1 and 2 as an XY plot produces a biomechanical mandibular morphospace. In
 our main analyses the first 10 axes were used to calculate biomechanical
 disparity, together with binary occurrence and groups files using the MDA
 add-on for MATLAB. Data regarding the stratigraphic occurrences and
 groupings for each taxon can be found in the electronic supplementary
 material accompanying our article (Table S1).