The First Ornithosuchid from Brazil and Its Macroevolutionary and Phylogenetic Implications for Late Triassic Faunas in Gondwana
Total Page:16
File Type:pdf, Size:1020Kb
Editors' choice The first ornithosuchid from Brazil and its macroevolutionary and phylogenetic implications for Late Triassic faunas in Gondwana RODRIGO T. MÜLLER, M. BELÉN VON BACZKO, JULIA B. DESOJO, and STERLING J. NESBITT Müller, R.T., Baczko, M.B. von, Desojo, J.B., and Nesbitt, S.J. 2020. The first ornithosuchid from Brazil and its macro- evolutionary and phylogenetic implications for Late Triassic faunas in Gondwana. Acta Palaeontologica Polonica 65 (1): 1–10. Ornithosuchidae is one of the most enigmatic clades of Triassic pseudosuchians. The group is composed by three carnivo- rous species that were excavated from Upper Triassic beds of Scotland and Argentina. We describe the first ornithosuchid from the Upper Triassic sediments of Brazil and explore its phylogenetic affinities and implications for the evolution of the group. Dynamosuchus collisensis gen. et sp. nov. was found as the sister taxon of the Argentinean form Venaticosuchus rusconii. These relationships reject a potential endemic radiation of ornithosuchids from the Ischigualasto-Villa Unión Basin and would better support multiple diversification events. Our findings with ornithosuchids is consistent with the pattern reported for proterochampsid and erpetosuchid archosauriforms from Ischigualasto-Villa Unión and the Paraná basins. In addition, the presence of an ornithosuchid in the Late Triassic of Brazil suggests that ornithosuchids were more widespread than previously thought in the southern hemisphere. The new ornithosuchid further demonstrates a faunistic link between the Argentinean and Brazilian basins during the Carnian. Finally, the discovery of the new species provides the first clue of a putative necrophagous vertebrate from the oldest dinosaur-bearing beds and expands our knowledge regarding the trophic structure of the Late Triassic of Brazil. Key words: Archosauria, Pseudosuchia, Ornithosuchidae, biogeography, phylogeny, Carnian, Santa Maria Formation, South America. Rodrigo T. Müller [[email protected]], Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polêsine, RS 598, 97230-000, Brazil. M. Belén Von Baczko [[email protected]] and Julia B. Desojo [[email protected]], División Paleonto- logía de Vertebrados, Museo de La Plata, Paseo del Bosque s/n (B1900FWA), La Plata, Buenos Aires, Argentina; Con- sejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290 (C1425FQB), Ciudad Autóno- ma de Buenos Aires, Argentina. Sterling J. Nesbitt [[email protected]], Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA. Received 2 July 2019, accepted 18 November 2019, available online 31 January 2020. Copyright © 2020 R.T. Müller et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License (for details please see http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. matic clades. Coined by Huene in 1908, Ornithosuchidae Introduction has a long and controversial taxonomic history. The clade has been found in different phylogenetic positions across The radiation of pseudosuchian archosaurs during the Archosauria (e.g., Gauthier 1986; Sereno 1991; Nesbitt Triassic Period is characterized by the origin and extinction 2011; Ezcurra 2016). Nevertheless, most hypotheses follow- of several peculiar and disparate clades, such as Aetosauria ing Sereno (1991) converged on a position near the base of (Desojo et al. 2013; Parker 2016), Erpetosuchidae (Benton Pseudosuchia. Three species form the clade: Ornithosuchus and Walker 2002; Nesbitt and Butler 2013; Ezcurra et al. woodwardi (Newton, 1894), from the late Carnian–early 2017; Lacerda et al. 2018), Gracilisuchidae (Butler et al. 2014; Norian, the Lossiemouth Sandstone Formation, Scotland Lecuona et al. 2017), and Ornithosuchidae (Walker 1964; (Newton 1894; Walker 1964); Venaticosuchus rusconii Bonaparte 1970; Baczko et al. 2014; Baczko and Desojo (Bonaparte, 1970) from the late Carnian of the Ischigualasto 2016; Baczko 2018). The latter is one of the most enig- Formation, Argentina (Baczko et al. 2014; Baczko 2018); Acta Palaeontol. Pol. 65 (1): 1–10, 2020 https://doi.org/10.4202/app.00652.2019 2 ACTA PALAEONTOLOGICA POLONICA 65 (1), 2020 A BRAZIL Janner site Sanga do Cabral Fm. B Santa Maria Fm. Caturrita Fm. Botucatu Fm. Serra Geral Fm. Cenozoic deposits urban area Fig. 1. A. Location map of the Janner site and the surface distribution of the geologic units in the area (modified from Müller et al. 2017). B. Stratigraphic column of the Janner site (modified from Da-Rosa 2015) depicting its fossiliferous content: 1, Exaeretodon; 2, Hyperodapedon; 3, Pampadromaeus; 4, Trucidocynodon; 5, Bagualosaurus; and 6, the new ornithosuchid. and Riojasuchus tenuisceps (Bonaparte, 1967) from the Instituto Miguel Lillo, Tucumán, Argentina; PVSJ, División Norian of the Los Colorados Formation, Argentina (Baczko de Paleontología de Vertebrados del Museo de Ciencias and Desojo 2016; Baczko et al. 2020). All members of this Naturales y Universidad Nacional de San Juan, San Juan, group are carnivorous, putatively scavengers and faculta- Argentina; SMNS, Staatliches Museum für Naturkunde, tive bipedal during fast gaits (Walker 1964; Baczko and Stuttgart, Germany; TTUP, Museum of Texas Tech Uni- Ezcurra 2013; Baczko 2018). Nevertheless, the fossil record versity, Lubbock, Texas, USA; UFRGS, Universidade Fede- of the group is geographically limited and so far, no remains ral do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, outside Ischigualasto-Villa Union Basin (Argentina) or the Brazil. Lossiemouth Sandstone Formation (Scotland) have been identified, thus leaving a large gap in their potential biogeo- Nomenclatural acts.—This published work and the nomen- graphic distribution. Here, we describe the first partial skel- clatural acts it contains, have been registered in ZooBank: eton of an ornithosuchid from the Upper Triassic sediments urn:lsid:zoobank.org:pub:A90DC693-B65F-472D-AA40-3C608C00 of Brazil (Fig. 1) and explore its phylogenetic affinities and B8D5 implications for the evolution of the group. Institutional abbreviations.—CAPPA/UFSM, Centro Material and methods de Apoio à Pesquisa Paleontológica da Quarta Colônia/ Universidade Federal de Santa Maria, São João do Polêsine, In order to test its phylogenetic affinities and potential im- Rio Grande do Sul, Brazil; CRILAR-Pv, Centro Regional plications for the understanding of pseudosuchian evolution, de Investigaciones y Transferencia Tecnológica de La Rioja, the new taxon was scored in the data matrix of Ezcurra et Paleontología de Vertebrados, Anillaco, La Rioja, Argen- al. (2017). This data matrix was employed because of the tina; NHMUK PV, Natural History Museum, London, UK; large sample of erpetosuchids included, whose importance PIN, Paleontological Institute of the Russian Academy of is crucial for this study because they were proposed as sister Sciences, Moscow, Russia; PIMUZ, Paläontologisches group of ornithosuchids (Ezcurra et al. 2017; Lacerda et Institut und Museum der Universität Zurich, Switzerland; al. 2018). The Brazilian erpetosuchid Pagosvenator can- PULR, Paleontología, Universidad Nacional de La Rioja, delariensis (Lacerda et al. 2018) which was published after La Rioja, Argentina; PVL, Paleontología de Vertebrados, Ezcurra et al. (2017) was also included here. Therefore, the MÜLLER ET AL.—LATE TRIASSIC ORNITHOSUCHID FROM BRAZIL 3 final data matrix includes 676 characters and 109 terminal correlation with radioisotope dating of another Brazilian site (Langer taxa. Our data matrix was subjected to an equally weighted et al. 2018) and Argentine beds from the La Peña Member of the Is- parsimony analysis in TNT v. 1.1 (Goloboff et al. 2008). The chigualasto Formation (Martínez et al. 2011) with the same taxa. characters treated by Ezcurra et al. (2017) as additive (1, 2, Diagnosis.—Dynamosuchus collisensis differs from all 7, 10, 17, 19, 20, 21, 28, 29, 36, 40, 42, 50, 54, 66, 71, 75, 76, other known ornithosuchids based on a unique combination 122, 127, 146, 153, 156, 157, 171, 176, 177, 187, 202, 221, of character states (* autapomorphy): dorsal process of the 227, 263, 266, 279, 283, 324, 327, 331, 337, 345, 351, 352, quadratojugal mostly dorsally oriented and with the lateral 354, 361, 365, 370, 377, 379, 398, 410, 424, 430, 435, 446, surface densely covered by rugosities; additional foramen 448, 454, 458, 460, 463, 472, 478, 482, 483, 489, 490, 504, on the medial wall of the quadrate foramen*; parabasi- 510, 516, 529, 537, 546, 552, 556, 557, 567, 569, 571, 574, sphenoid component of the basal tubera ventrally separated 581, 582, 588, 648, 652, and 662) were also treated as such from the basipterygoid process by a slight notch at the mid- in our analysis. Petrolacosaurus kansensis was used to root line; main axis of the parabasisphenoid process posteroven- the most parsimonious trees (MPTs), which were recovered trally direc ted; surangular with a conspicuous lateral shelf with a “Traditional search” (random addition sequence + and an anteroposteriorly wide surangular foramen; anterior tree bisection reconnection) with 1000 replicates of Wagner dorsal vertebrae with anterior and posterior centrodiapoph- trees (with random seed = 0), and using tree bisection re- yseal laminae and without prezygodiapophyseal and post- connection and branch swapping (holding 10