DOI: 10.5061/dryad.8kprr4xxr
title: A new notosuchian crocodyliform from the Paleocene of Patagonia and the survival of a large-bodied terrestrial lineage across the K–Pg mass extinction

description: Sebecid notosuchians are the only terrestrial crocodyliforms to survive
 the Cretaceous–Paleogene extinction, 66 Ma, which eliminated large-bodied
 species (~&gt;5 kg) in terrestrial ecosystems. Early sebecid evolution
 is unclear due to the scarcity of remains from both sides of the boundary.
 We present the stratigraphically earliest post-extinction notosuchian
 record, from the lower Paleocene Salamanca Formation of Patagonia.
 Tewkensuchus salamanquensis n. gen. n. sp. has unique features, including
 a skull roof with elevated lateral margins, and an accessory peg and
 socket articulation between the postorbital and posterior palpebral. Our
 phylogenetic analysis allies Tewkensuchus with a clade of predatorial
 crocodyliforms from the Eocene of Europe (and possibly of Africa, as
 Eremosuchus may belong to this clade). This clade forms the sister taxon
 of South American sebecids. We name Sebecoidea for this more inclusive
 clade of Eurogondwanan notosuchians and suggest that its spatial
 distribution reflects earlier diversification and dispersal events, which
 are only partially known. We estimate a body mass of ~300 kg for
 Tewkensuchus, one of the largest known notosuchians. Phylogenetic
 optimization of notosuchian body size change reconstructs a
 Cretaceous–Paleogene boundary-crossing sebecoidean lineage with an
 estimated mass between 332–443 kg. This provides the first support for
 survival of a large-bodied terrestrial vertebrate lineage across the K-Pg
 boundary.
description: # A new notosuchian crocodyliform from the Paleocene of Patagonia and the
 survival of a large-bodied terrestrial lineage across the K–Pg mass
 extinction
 [https://doi.org/10.5061/dryad.8kprr4xxr](https://doi.org/10.5061/dryad.8kprr4xxr) # Title of dataset: A new notosuchian crocodyliform from the Paleocene of Patagonia and the survival of a large-bodied terrestrial lineage across the K–Pg mass extinction. Supporting data # Author Information: A. Investigator Contact Information Name: Gonzalo Gabriel Bravo Institution: CONICET, Instituto Superior de Correlación Geológica, Universidad Nacional de Tucumán, Facultad de Ciencias Naturales e I.M.L., Av. Presidente Perón S/N, Yerba Buena, 4107, Tucumán, Argentina. Email: [gonzagbravo@gmail.com](mailto:gonzagbravo@gmail.com) B. Co-investigator Contact Information Name: Diego Pol Institution: CONICET, Museo Argentino de Ciencias Naturales Bernardino Rivadavia (MACN), Av. Ángel Gallardo 470, C1405DJR,Buenos Aires, Argentina. Email: [cacopol@gmail.com](mailto:cacopol@gmail.com) C. Co-investigator Contact Information Name: Juan Martín Leardi Institution: 1)CONICET, Instituto de Estudios Andinos “Don Pablo Groeber” (IDEAN), Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldez 2160, Ciudad Universitaria, Pabellón 2, C1428EGBA, Buenos Aires, Argentina. 2)Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldez 2160, Ciudad Universitaria, Pabellón 2, C1428EGBA, Buenos Aires, Argentina. Email: [jmleardi@gl.fcen.uba.ar](mailto:jmleardi@gl.fcen.uba.ar) D. Co-investigator Contact Information Name: Javier Marcelo Krause Institution: 1)CONICET, Museo Paleontológico Egidio Feruglio, Av. Fontana 140, Trelew, 9100, Chubut, Argentina; [mkrause@mef.org.ar](mailto:mkrause@mef.org.ar); 2)Universidad Nacional de Río Negro, Av. Roca 1242, General Roca, 8332, Río Negro, Argentina Email: [mkrause@mef.org.ar](mailto:mkrause@mef.org.ar) E. Co-investigator Contact Information Name: Cecily S. C. Nicholl Institution: Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, United Kingdom. Email: [cecily.nicholl@ucl.ac.uk](mailto:cecily.nicholl@ucl.ac.uk) F. Co-investigator Contact Information Name: Guillermo W. Rougier Institution: Department of Anatomical Sciences and Neurobiology, University of Louisville, 511 S. Floyd Street, Louisville, Kentucky, 40202, U.S.A. Email: [grougier@louisville.edu](mailto:grougier@louisville.edu) G. Co-investigator Contact Information Name: Philip D. Mannion Institution: Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, United Kingdom. Email: [philipdmannion@gmail.com](mailto:philipdmannion@gmail.com) ## Description of the data and file structure 1\. Supporting data 2: This file contains the dataset of notosuchians, including cranial measurements and calculations with estimates of body mass. Sheet 1, called "Dataset Notosuchia", contains the list of taxa used in the body mass analyses. All measurements were taken with a digital caliper when the material was firsthand. When the material was photographic, measurements were taken using the ImageJ program, with the scale calibrated beforehand. All measurements were recorded in this dataset in millimeters (mm). The references for each measurement are as follows: DCL, dorsal cranial length; ODCL, orbital-dorsal cranial length; DFrL, dorsal frontal length; BM, body mass. Sheet 2, called "Cranial length of sebecids", contains both actual and inferred measurements for the sebecoidean notosuchians. The inferred measurements were obtained from the DFrL values using a linear regression equation derived through the R program. These inferred values are calculated in the columns "Estimated DCL (mm)" and "Estimated ODCL (mm)." Sheet 3, called "Body mass using equation from F", includes the body mass calculations made using Farlow's (2005) equation. Both the Excel sheet (.xlsx) titled "Cranial length of sebecids" and the one titled "Body mass using equation from F" include scatter plots that support the data used and the estimates made. On the other hand, the data tables without any formatting or graphs are provided separately in csv format. ## Description of the data published on Zenodo 1\. Supporting data 1: This file contains additional information to the main body of the work, including a Geological Setting section, more detailed anatomical descriptions and comparison, and additional information on the phylogenetic analysis (procedures and results). In the Geological Setting section, you will find additional information about the provenance site of the holotype of *T*described in this work (MPEF-PV 3700), as well as some details about its discovery and the legal permits for its extraction. In the phylogenetic analysis section, you will find the list of morphological characters used and the list of taxa with their corresponding collection references. Additionally, this section provides details on how the unstable taxa for the data matrix were identified, the process used to search for the supports for each node of interest (Sebecosuchia, Sebecoidea, and Sebecidae), and how the analysis of the optimization of the continuous character Dorsal Cranial Length (DCL) was conducted. 2\. Phylogenetic analysis: This folder contains the files used for reproduce the phylogenetic analyses. It contains the morphological matrix, an updated version of the matrix from Bravo et al., 2021 used for the main phylogenetic analysis(a) and its nexus format (b), the file of most parsimonious trees resulting from the TNT analysis (c), and the morphological matrix including the continuous characters Dorsal Cranial Length (Character 1), Body Mass (Character 2), and logaritm of Body Mass (character 3) (d). a. Tewkensuchus_444x121.tnt b. Tewkensuchus_444x121.nex c. Tewkensuchus_444x121.ctf d. Tewkensuchus_Optimization.tnt 4\. Script package: This folder contains scripts for viewing and exporting ambiguous and unambiguous synapomorphies from TNT (a), detecting unstable taxa and viewing their alternative positions in the phylogenetic topology (b), determining the jackknife support values of nodes in a reduced consensus tree that excludes unstable taxa (c), and exporting a tree in SVG format that marks the mapping of a desired character in different colors (d), and the file that includes the R script used to obtain the linear regression equation (e). a. APOLISTAMB.RUN b. iterpcr.run c. pcrjack.run d. colorcontBlueRed.run e. R_linear_regression The execution of each script is outlined in the respective sections of Supporting Data 1.