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Book Chapter

The Late Triassic dinosauromorph Sacisaurus agudoensis (Caturrita Formation; Rio Grande do Sul, Brazil): anatomy and affinities

By
Max C. Langer
Max C. Langer
Departamento de Biologia-FFCLRP, Universidade de São Paulo, 14040-901 Ribeirão Preto, Brazil
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Jorge Ferigolo
Jorge Ferigolo
Museu de Ciâncias Naturais, Fundação Zoobotânica do Rio Grande do Sul, 90690-000 Porto Alegre, Brazil
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Published:
January 01, 2013

Abstract

Silesauridae is an exclusively Triassic group of dinosauromorphs, knowledge on the diversity of which has increased dramatically in the last few years. Silesaurid relationships are still contentious, as a result in part of different homology statements, particularly regarding the typical edentulous mandible tip of these animals. One of the most complete silesaurids yet discovered is Sacisaurus agudoensis from the Caturrita Formation (Late Triassic: Norian) of Rio Grande do Sul, Brazil, represented by numerous isolated bones recovered from a single site. The anatomy of S. agudoensis is fully described for the first time here, and comparisons are provided to other basal dinosauromorphs. S. agudoensis is a small-bodied animal (less than 1 m in length) that possesses a dentition consisting of leaf-shaped crowns with large denticles in the carinae, a plesiomorphic propubic pelvis with an almost fully closed acetabulum, elongate distal hindlimbs suggesting well-developed cursorial ability, and a laterally projected outer malleolus in the tibia. All previous numerical phylogenies supported a non-dinosaur dinosauromorph affinity for Silesauridae, but the reanalysis of one of those studies suggests that a position within Dinosauria is not unlikely, with silesaurids forming the basal branch of the ornithischian lineage.

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Contents

Geological Society, London, Special Publications

Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin

S. J. Nesbitt
S. J. Nesbitt
University of Washington, USA
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J. B. Desojo
J. B. Desojo
Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Argentina
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R. B. Irmis
R. B. Irmis
Natural History Museum of Utah, USA
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Geological Society of London
Volume
379
ISBN electronic:
9781862396395
Publication date:
January 01, 2013

GeoRef

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