These theropods were slender, gracefully built, predatory animals. It is very likely that they fed on small lizards, fish and possibly carrion, as they were too light to kill larger animals. They had three clawed fingers and a flexible thumb, the function of which is not guaranteed. They were one to three meters long and could have been relatively fast runners. The fossil remains of two taxa, Coelophysis and Megapnosaurus , were found by the dozen and hundreds respectively in one deposit. It is therefore assumed that the animals lived in larger groups.
Until recently, the Coelophysoids, especially the genus Coelophysis , were said to have cannibalism . However, new research has shown that the remains of supposedly own young animals were Saltoposuchids , ancestors of the crocodiles .
The coelophysoids differ from the more primitive theropods in the construction of the upper jawbones , which have a strange kink . Apart from the Coelophysoids, only the Spinosaurs had this strange characteristic . Possibly this skull shape reduced the weight of the head.
It is controversial whether the Coelophysoids are counted among the Ceratosauria or whether they branch off from the family tree at an earlier point in time than this. Various authors generally assign them to the Neotheropoda , more recent works such as Hendrickx & Mateus (2014) place them in the Tetanurae . Still others like Nesbitt et al. (2009) question the status of the Coelophysoidea as a valid taxon in general.
Two of the possibilities for the systematic position of the Coelophysids are shown by the following cladograms :
↑ AM Yates. 2005: A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods . Palaeontologia Africana 41: 105-122 
↑ C. Hendrickx and O. Mateus. 2014: Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth . Zootaxa 3759 (1): 1-74 doi : 10.11646 / zootaxa.3759.1.1
^ SJ Nesbitt, ND Smith, RB Irmis, AH Turner, A. Downs and MA Norell. 2009: A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs . Science 326: 1530-1533 doi : 10.1126 / science.1180350 .
↑ Nesbitt, Sterling J .; Ezcurra, Martin D. (July 13, 2015): The early fossil record of dinosaurs in North America: A new neotheropod from the base of the Upper Triassic Dockum Group of Texas . Acta Palaeontologica Polonica 60. doi : 10.4202 / app.00143.2014
^ Hai-Lu You, Yoichi Azuma, Tao Wang, Ya-Ming Wang & Zhi-Ming Dong: The first well-preserved coelophysoid theropod dinosaur from Asia. Zootaxa 3873 (3): 233-249 (Oct. 16, 2014)