14 August 2017 A New Early Coelophysoid Neotheropod from the Late Triassic of Northwestern Argentina
Martín D. Ezcurra
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Neotheropoda includes the vast majority of the predatory dinosaurs and their oldest members are Late Triassic in age. The Triassic neotheropod record is restricted to North America and Europe with the exception of a few specimens from South America, which includes Zupaysaurus rougieri and Lucianovenator bonoi. Here, the South American record of the group is enriched with the description of the new genus and species Powellvenator podocitus from the middle Norian Los Colorados Formation (Ischigualasto-Villa Unión Basin) of northwestern Argentina. The new taxa are represented by previously undescribed partial hindlimbs collected by J. F. Bonaparte and associated to the hypodigm of the pseudosuchian Riojasuchus tenuisceps. In addition, a specimen originally interpreted by Bonaparte in 1972 as an indeterminate coelurosaur is here referred to the new species. Powellvenator podocitus differs from other basal dinosaurs in character-states that include an astragalus with a distinctly sigmoid posterodorsal margin and a rounded dorsal expansion on the anteromedial portion of the astragalar body in anterior view, calcaneum with a laterally projected flange, and strongly reduced shaft of metatarsal II. The phylogenetic relationships of the new species were tested in a comprehensive analyses focused on early neotheropods, which recovered Powellvenator podocitus within Coelophysoidea and as the sister-taxon of Procompsognathus triassicus and Coelophysinae. Powellvenator podocitus represents the first coelophysoid from South America together with Lucianovenator bonoi from the Marayes-El Carrizal Basin.

Martín D. Ezcurra "A New Early Coelophysoid Neotheropod from the Late Triassic of Northwestern Argentina," Ameghiniana 54(5), 506-538, (14 August 2017). https://doi.org/10.5710/AMGH.04.08.2017.3100
Received: 15 March 2017; Accepted: 1 August 2017; Published: 14 August 2017
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