Pendraig milnerae, a new small-sized coelophysoid theropod from the Late Triassic of Wales

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  • Stephan Spiekman
  • Martin Ezcurra
  • Richard Butler
  • Nicholas Fraser
  • Susannah Maidment


We describe a new small-bodied coelophysoid theropod dinosaur, Pendraig milnerae gen. et sp. nov, from the Late Triassic fissure fill deposits of Pant-y-ffynnon in southern Wales. The species is represented by the holotype, consisting of an articulated pelvic girdle, sacrum and posterior dorsal vertebrae, and an associated left femur, and by two referred specimens, comprising an isolated dorsal vertebra and a partial left ischium. Our phylogenetic analysis recovers Pendraig milnerae as a non-coelophysid coelophysoid theropod, representing the first named unambiguous theropod from the Triassic of the United Kingdom. Recently it has been suggested that Pant-y-ffynnon and other nearby Late Triassic to Early Jurassic fissure fill faunas might have been subjected to insular dwarfism. To test this hypothesis for Pendraig milnerae, we performed an ancestral state reconstruction analysis of body size in early neotheropods. Although our results indicate that a reduced body size is autapomorphic for Pendraig milnerae, some other coelophysoid taxa show a similar size reduction, and there is therefore ambiguous evidence to indicate that this species was subjected to dwarfism. Our analyses further indicate that, in contrast to averostran-line neotheropods, which increased in body size during the Triassic, coelophysoids underwent a small body size decrease early in their evolution.


Original languageEnglish
Article number210915
Number of pages27
JournalRoyal Society Open Science
Issue number10
Publication statusPublished - 6 Oct 2021


  • Pendraig, Coelophysoidea, Theropoda, Triassic, body size evolution, osteology