DOI: 10.5061/dryad.ghx3ffc27
title: Braincase and digital endocast of a loricatan pseudosuchian (Reptilia: Archosauria) from the Upper Triassic of Nova Scotia (Canada)

description: We present a detailed description of an incomplete but excellently
 preserved braincase and a digitally generated endocast of a pseudosuchian
 archosaur from the Upper Triassic (Carnian) Evangeline Member of the
 Wolfville Formation of Nova Scotia (Canada). The general morphology of the
 braincase particularly resembles that of the rauisuchid Postosuchus
 kirkpatricki from the Upper Triassic (Norian) of Texas. Indeed, the
 quantitative phylogenetic analyses found the Wolfville specimen within
 Rauisuchidae (Postosuchus spp., Polonosuchus silesiacus, and Rauisuchus
 tiradentes) among loricatan pseudosuchians based on the presence of a deep
 and dorsoventrally elongate basisphenoid recess. Although the specimen
 described here shows differences with Postosuchus kirkpatricki and
 Postosuchus alisonae, its fragmentary condition and the absence of
 overlapping elements with other rauisuchids (Polonosuchus silesiacus and
 Rauisuchus tiradentes) led us to be cautious and identify it as aff.
 Postosuchus sp. The Wolfville rauisuchid braincase provides evidence for
 the presence of this clade in low paleolatitudes during the Carnian,
 bridging the higher paleolatitude occurrences of Rauisuchidae in southern
 Brazil and in Poland, respectively.
description: Specimen scan and digitalization The surfaces
 of the braincase YPM VPPU 020750 were 3D-scanned with an Artec Spider 3D
 Scanner, and the scanning data were collected and processed in Geomagic
 Studio (3D systems, Rock Hill, South Carolina). Images of 3D surface
 meshes were produced using MeshLab. Subsequently, the
 specimen was mCT-scanned using a GE Phoenix v|tome| xm 240/180 Dual mCT
 system at the National Museum of Natural History (Smithsonian Institution)
 with a voxel size of 125 mm, a source voltage of 175 kV, and a source
 current of 150 mA. It generated 1432 images, each with a height of 2024
 pixels and a width of 2014 pixels. The scan data were exported in DICOM
 format and subsequently imported into the digital visualization software
 Avizo (v.9.1). The endocast was reconstructed using the Segmentation
 Editor with key anatomical structures isolated and highlighted in
 different colors. Finally, images of the digital endocast visualized
 inside the transparent braincase were exported.
 Phylogenetic analyses The phylogenetic
 relationships of YPM VPPU 020750 were tested using the character-taxon
 matrix of Desojo and Rauhut (2024), which is the latest iteration of the
 dataset originally published by Nesbitt (2011). After adding YPM VPPU
 020750, the modified version of the data matrix is composed of 454
 characters scored across 97 active terminals (Supplementary Material). The
 data set was analyzed under implied weighting maximum parsimony in the
 program TNT version 1.6 (Goloboff and Morales 2023). This decision of
 weighting against homoplasy follows the results of the analyses of
 Goloboff et al. (2018) (based on simulations) and Ezcurra (2024) (based on
 empirical data), in which implied weighting outperformed equal weighting
 in topological accuracy and stability, respectively. A series of analyses
 were conducted with a range of concavity constant values (k) between 5 and
 11 following the suggestion of Ezcurra (2024) for a matrix with the number
 of terminals used here. The following 22 characters were considered as
 ordered following Desojo and Rauhut (2024): 32, 52, 121, 137, 139, 156,
 168, 188, 223, 247, 258, 269, 271, 291, 297, 314, 328, 356, 371, 399, 413,
 and 446. The search strategy initially used a combination of the
 tree-search algorithms sectorial searches, drifting, ratchet, and tree
 fusing, until 100 hits of the same minimum tree length were achieved. The
 shortest trees obtained were then subjected to a final round of TBR branch
 swapping. Zero length branches in any of the recovered MPTs were
 collapsed. All the trees were rooted with <em>Mesosuchus
 browni</em>. Homoplasy indices for each analysis under the different
 k values were calculated with ‘STATSb.run’ (Spiekman et al., 2021). Group
 supports were quantified using no-zero weight symmetric resampling
 analyses, using 10,000 pseudo-replications (each with 10 replications of
 Wagner trees + TBR) and reporting both absolute and GC (group
 present/contradicted) frequencies. Finally, a global strict consensus tree
 (GSCT) was generated from all the most parsimonious trees (MPTs) found in
 all the analyses using the different k values. Similarly, absolute and GC
 resampling frequencies were calculated from all the resampling trees
 recovered using the different k values and plotted on the branches of the
 GSCT. These analyses were implemented using the TNT
 script ‘phylo_analyses_IW_and_eqW.run’, which uses a series of arguments
 to customize automatized analyses (see README file in Supplementary
 Material). This script, ‘STATSb.run’, and data matrix files should be in
 the same folder (working directory). The script needs the following seven
 arguments that allow the user to customize the analysis: 1) the name of
 the matrix file without the “.tnt” extension, 2) character weighting
 treatment (0 = implied weighting, 1 = implied weighting and equal weights,
 2 = equal weights), 3) the lower limit of the <em>k</em>
 values range, 4) the upper limit of the <em>k</em> values
 range, 5) type of tree search (0 = traditional search, 1 = new technology
 search, 2 = consensus stabilization search), 6) number of iterations
 during tree search, and 7) the number of pseudo-replications of the
 resampling analyses. Hence, to reproduce the analyses conducted here, the
 script should be run as follows in TNT: ‘run phylo_analyses_IW_and_eqW.run
 Nesbitt_matrix_YPM 0 5 11 1 100 1000;’.
description: # Braincase and digital endocast of a loricatan pseudosuchian (Reptilia:
 Archosauria) from the Upper Triassic of Nova Scotia (Canada) Dataset DOI:
 [10.5061/dryad.ghx3ffc27](10.5061/dryad.ghx3ffc27) ## Description of the
 data and file structure No experiments involved. ### Files and variables
 #### File: Nesbitt_matrix_YPM.nex **Description:** Character-taxon matrix
 in NEXUS format for phylogenetic analysis. #### File:
 Nesbitt_matrix_YPM.tnt **Description:** Character-taxon matrix in .tnt
 format for phylogenetic analysis using TNT v. 1.6. #### File:
 YPM_VPPU_020750_Endocast.stl **Description:** Digitally generated endocast
 based microCT-scanning data of the braincase. #### File:
 YPM_VPPU_020750_Labyrinth.stl **Description:** Digitally generated cast of
 inner ear labyrinth based microCT-scanning data of the braincase. ####
 File: YPM_VPPU_020750_Braincase.stl **Description:** .stl file of 3D
 rendering of the braincase of YPM VPPU 020750.  ## Code/software 3D
 scanning: Geomagic Studio, MeshLab MicroCT scanning: Avizo v. 9.1
 Phylogenetic analysis: TNT v. 1.6 ## Access information Other publicly
 accessible locations of the data: * Scanning images from Department of
 Paleobiology, National Museum of Natural History Data was derived from the
 following sources: * All generated by authors