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From the Chañares Formation (Early Carnian), Argentina comptes rendus palevol 2020 19 3 DIRECTEURS DE LA PUBLICATION / PUBLICATION DIRECTORS : Bruno David, Président du Muséum national d’Histoire naturelle Étienne Ghys, Secrétaire perpétuel de l’Académie des sciences RÉDACTEURS EN CHEF / EDITORS-IN-CHIEF : Michel Laurin (CNRS), Philippe Taquet (Académie des sciences) ASSISTANTE DE RÉDACTION / ASSISTANT EDITOR : Adenise Lopes (Académie des sciences; [email protected]) MISE EN PAGE / PAGE LAYOUT : Martin Wable (Muséum national d’Histoire naturelle; [email protected]) RÉDACTEURS ASSOCIÉS / ASSOCIATE EDITORS : Micropaléontologie/Micropalaeontology Maria Rose Petrizzo (Università di Milano, Milano) Paléobotanique/Palaeobotany Cyrille Prestianni (Royal Belgian Institute of Natural Sciences, Brussels) Métazoaires/Metazoa Annalisa Ferretti (Università di Modena e Reggio Emilia, Modena) Paléoichthyologie/Palaeoichthyology Philippe Janvier (Muséum national d’Histoire naturelle, Académie des sciences, Paris) Amniotes du Mésozoïque/Mesozoic amniotes Hans-Dieter Sues (Smithsonian National Museum of Natural History, Washington) Tortues/Turtles Juliana Sterli (CONICET, Museo Paleontológico Egidio Feruglio, Trelew) Lépidosauromorphes/Lepidosauromorphs Hussam Zaher (Universidade de São Paulo) Oiseaux/Birds Éric Buffetaut (CNRS, École Normale Supérieure, Paris) Paléomammalogie (petits mammifères)/Palaeomammalogy (small mammals) Robert Asher (Cambridge University, Cambridge) Paléomammalogie (mammifères de moyenne et grande taille)/Palaeomammalogy (large and mid-sized mammals) Lorenzo Rook (Università degli Studi di Firenze, Firenze) Paléoanthropologie/Palaeoanthropology Roberto Macchiarelli (Université de Poitiers, Poitiers) Archéologie préhistorique/Prehistoric archaeology Marcel Otte (Université de Liège, Liège) COUVERTURE / COVER : Composition à partir d’illustrations de l’article / Made from the Figures of the article. Comptes Rendus Palevol est indexé dans / Comptes Rendus Palevol is indexed by: – Cambridge Scientific Abstracts – Current Contents® Physical – Chemical, and Earth Sciences® – ISI Alerting Services® – Geoabstracts, Geobase, Georef, Inspec, Pascal – Science Citation Index®, Science Citation Index Expanded® – Scopus®. Les articles ainsi que les nouveautés nomenclaturales publiés dans Comptes Rendus Palevol sont référencés par : Articles and nomenclatural novelties published in Comptes Rendus Palevol are registered on: – ZooBank® (http://zoobank.org) Comptes Rendus Palevol est une revue en flux continu publiée par les Publications scientifiques du Muséum, Paris et l’Académie des sciences, Paris Comptes Rendus Palevol is a fast track journal published by the Museum Science Press, Paris and the Académie des sciences, Paris Les Publications scientifiques du Muséum publient aussi / The Museum Science Press also publish: Adansonia, Geodiversitas, Zoosystema, Anthropozoologica, European Journal of Taxonomy, Naturae, Cryptogamie sous-sections Algologie, Bryologie, Mycologie. L’Académie des sciences publie aussi / The Académie des sciences also publishes: Comptes Rendus Mathématique, Comptes Rendus Physique, Comptes Rendus Mécanique, Comptes Rendus Chimie, Comptes Rendus Géoscience, Comptes Rendus Biologies. Diffusion – Publications scientifiques Muséum national d’Histoire naturelle CP 41 – 57 rue Cuvier F-75231 Paris cedex 05 (France) Tél. : 33 (0)1 40 79 48 05 / Fax : 33 (0)1 40 79 38 40 [email protected] / http://sciencepress.mnhn.fr Académie des sciences, Institut de France, 23 quai de Conti, 75006 Paris. © Publications scientifiques du Muséum national d’Histoire naturelle / © Académiedes sciences, Paris, 2020 ISSN (imprimé / print) : 1631-0683/ ISSN (électronique / electronic) : 1777-571X New information on the anatomy and histology of Gracilisuchus stipanicicorum (Archosauria: Pseudosuchia) from the Chañares Formation (early Carnian), Argentina LECUONA Agustina CONICET, Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro (UNRN), Av. Roca 1242, R8332EXY, General Roca, Pcia. de Río Negro (Argentina) [email protected] (corresponding author) DESOJO Julia Brenda CONICET, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Paseo del Bosque s/n°, B1900FWA, La Plata (Argentina) [email protected] CERDA Ignacio Alejandro CONICET, Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro (UNRN), Av. Roca 1242, R8332EXY,General Roca, Pcia. de Río Negro (Argentina) and Museo Provincial “Carlos Ameghino”, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta), CP8300, Cipolletti, Pcia. de Río Negro (Argentina) [email protected] Submitted on 8 January 2019 | accepted on 25 October 2019 | published on 2 September 2020 urn:lsid:zoobank.org:pub:BAB7B425-9315-4775-9432-4DD17DFF4921 Lecuona A., Desojo J. B. & Cerda I. A. 2020. — New information on the anatomy and histology of Gracilisuchus sti- panicicorum (Archosauria: Pseudosuchia) from the Chañares Formation (early Carnian), Argentina. Comptes Rendus Palevol 19 (3): 40-62. https://doi.org/10.5852/cr-palevol2020v19a3 ABSTRACT Gracilisuchus stipanicicorum Romer, 1972 is a basal suchian from the Late Triassic Chañares Forma- tion (Argentina), nested in the recently erected Gracilisuchidae, along with Turfanosuchus dabanensis Young, 1973 and Yonghesuchus sangbiensis Wu et al., 2001 from China. The six known specimens of Gracilisuchus Romer, 1972 preserve most of the skeleton, lacking only most of the shoulder girdle and forelimb. Our latest fieldwork has recovered two specimens that preserve previously unknown elements, including the humerus, radius, and ulna, as well as the femur, presacral vertebrae, and paramedian osteoderms. The femur and osteoderms were histologically sectioned, which has never been done for KEY WORDS Chañares Formation, Gracilisuchidae. The anatomical analysis revealed characters in the new elements that improve our Triassic, understanding of the anatomy of Gracilisuchus. Bone histology revealed that the specimen CRILAR Pseudosuchia, PV 490 died before reaching somatic maturity and that growth was relatively slow compared to other Gracilisuchidae, Bone Histology, pseudosuchians. This study increases the knowledge of the anatomy ofGracilisuchus and represents a Lamellar bone tissue. new step towards a broader understanding of Gracilisuchidae and basal suchian clades. COMPTES RENDUS PALEVOL • 2020 • 19 (3) © Publications scientifiques du Muséum et/and Académie des sciences, Paris. www.cr-palevol.fr 40 Lecuona A. et al. RÉSUMÉ Nouvelle information sur l’anatomie et l’histologie de Gracilisuchus stipanicicorum (Archosauria : Pseu- dosuchia) de la Formation Chañares (Carnian inférieur), Argentine. Gracilisuchus stipanicicorum Romer, 1972 est un suchien souche de la Formation Chañares du Trias supérieur (Argentine), inclus dans les Gracilisuchidae, un groupe récemment créé avec Turfanosu- chus dabanensis Young, 1973 et Yonghesuchus sangbiensis Wu et al., 2001 de Chine. Les six spécimens connus de Gracilisuchus Romer, 1972 conservent la majorité du squelette, à l’exception de la plupart de la ceinture scapulaire et du membre antérieur. Nos derniers travaux sur le terrain, ont exhumé deux spécimens qui préservent des éléments non encore connus, tels que l’humérus, le radius et l’ulna, ainsi qu’un fémur, des vertèbres et ostéodermes. Le fémur et les ostéodermes paramédiaux ont été section- nés en vue d’une histologie, encore jamais abordée chez les Gracilisuchidae. L’analyse anatomique a MOTS CLÉS Formation Chañares, révélé, dans les nouveaux éléments, des caracréristiques qui améliorent notre compréhension de l’ana- Trias, tomie de Gracilisuchus. L’histologie osseuse, elle, a révélé que l’individu CRILAR PV 490 était mort Pseudosuchiens, avant atteindre sa taille adulte et que sa croissance était relativement lente comparée à celle d’autres Gracilisuchidae, Histologie osseuse, pseudosuchiens. Cette étude approfondit la connaissance de Gracilisuchus et constitue un pas sup- Tissu osseux lamellaire. plémentaire vers une meilleure compréhension de Gracilisuchidae et des clades de suchiens souches. INTRODUCTION were gradually replaced by the bird-line clade of archosaurs (Avemetatarsalia), being today represented only by Crocodylia. Gracilisuchus stipanicicorum Romer, 1972 is a basal suchian Gracilisuchus stipanicicorum was previously known from archosaur from the Late Triassic of north-western Argentina six specimens housed in Argentina (Instituto Miguel Lillo, (Chañares Formation, Ischigualasto–Villa Unión Basin, early Tucumán and Museo de Ciencias Antropológicas y Naturales, Carnian; Desojo et al. 2011; Marsicano et al. 2016). This La Rioja) and the United States (Museum of Comparative species, discovered more than four decades ago (Bonaparte Zoology, Harvard University, Cambridge, Massachusetts), 1975; Romer 1972), has been subject to various phyloge- representing most of the skeleton but missing most of the pec- netic interpretations over the years but no detailed study toral girdle and forelimb elements. Some anatomical features has been made until recently (see Lecuona et al. 2017 for a including small size, open sutures in the skull and along the summary). Gracilisuchus Romer, 1972 is a monospecific genus axial skeleton, suggest that some specimens are possibly juve- nested within the recently erected family Gracilisuchidae niles (Lecuona et al. 2017). Recent fieldwork in the Chañares (Butler et al. 2014), along with the Chinese species Turfano- Formation (by Desojo & Lecuona in 2011 and 2013;
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