Gnathovorax cabreirai : a new early dinosaur and the origin and initial radiation of predatory dinosaurs

PeerJ

article

Cristian Pacheco¹  Rodrigo T. Müller²  Max Langer³  Flávio A. Pretto¹  Leonardo Kerber¹  Sérgio Dias da Silva¹ 

[1] Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria;Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria;Laboratório de Paleontologia, Universidade de São Paulo

关键词: Archosauria;    Brazil;    Carnian;    Herrerasauridae;    Paleobiology;    Santa Maria Formation;    Saurischia;    Triassic;    Candelária sequence;    Dinosauria;   

DOI  :  10.7717/peerj.7963

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Predatory dinosaurs were an important ecological component of terrestrial Mesozoic ecosystems. Though theropod dinosaurs carried this role during the Jurassic and Cretaceous Periods (and probably the post-Carnian portion of the Triassic), it is difficult to depict the Carnian scenario, due to the scarcity of fossils. Until now, knowledge on the earliest predatory dinosaurs mostly relies on herrerasaurids recorded in Carnian strata of South America. Phylogenetic investigations recovered the clade in different positions within Dinosauria, whereas fewer studies challenged its monophyly. Although herrerasaurid fossils are much better recorded in present-day Argentina than in Brazil, Argentinean strata so far yielded no fairly complete skeleton representing a single individual. Here, we describe Gnathovorax cabreirai, a new herrerasaurid based on an exquisite specimen found as part of a multitaxic association from southern Brazil. The type specimen comprises a complete and well-preserved articulated skeleton, preserved in close association (side by side) with rhynchosaur and cynodont remains. Given its superb state of preservation and completeness, the new specimen sheds light into poorly understood aspects of the herrerasaurid anatomy, including endocranial soft tissues. The specimen also reinforces the monophyletic status of the group, and provides clues on the ecomorphology of the early carnivorous dinosaurs. Indeed, an ecomorphological analysis employing dental traits indicates that herrerasaurids occupy a particular area in the morphospace of faunivorous dinosaurs, which partially overlaps the area occupied by post-Carnian theropods. This indicates that herrerasaurid dinosaurs preceded the ecological role that later would be occupied by large to medium-sized theropods.

【 授权许可】

CC BY