Coelophysoidea is an extinct clade of theropod dinosaurs common during the Late Triassic and Early Jurassic periods. They were widespread geographically, probably living on all continents. Coelophysoids were all slender, carnivorous forms with a superficial similarity to the coelurosaurs, with which they were formerly classified, and some species had delicate cranial crests. Sizes range from about 1 to 6 m in length. It is unknown what kind of external covering coelophysoids had, and various artists have portrayed them as either scaly or feathered. Some species may have lived in packs, as inferred from sites where numerous individuals have been found together.

Examples of coelophysoids include Coelophysis, Procompsognathus and Liliensternus. Most dinosaurs formerly referred to as being in the dubious taxon "Podokesauridae" are now classified as coelophysoids. The family Coelophysidae, which is contained within Coelophysoidea, flourished in the Late Triassic and Early Jurassic periods, and has been found on numerous continents. Many members of Coelophysidae are characterized by long, slender skulls and light skeletons built for speed. One member genus, Coelophysis, displays the earliest known furcula in a dinosaur.

History of Study

Under cladistic analysis, Coelophysidae was first defined by Paul Sereno in 1998 as the most recent common ancestor of Coelophysis bauri and Procompsognathus triassicus, and all of that common ancestor's descendants. Coelophysidae is part of the superfamily Coelophysoidea, which in turn is a subset of the larger Neotheropoda clade.

Anatomy

thumb|left|Skull diagrams of various coelophysoids

Despite their very early occurrence in the fossil record (early to middle Norian),

Coelophysids are characterized by slender, skinny builds and long, narrow skulls with large fenestrae to allow for a lighter skull. They are fairly primitive theropods, and so have fairly basal characteristics, such as hollow air sacs in the cervical vertebrae and obligate bipedalism.

Classification

Coelophysoids are classified as basal neotheropods that lie outside of Averostra. Many taxa that have been historically considered coelophysoids or coelophysids, have also been found elsewhere around the early theropod stem. Below is the phylogenetic analysis of Stephan Spiekman and colleagues from 2021, with taxa sometimes recovered as coelophysoids illustrated. Procompsognathus triassicus was discovered in Germany, and Camposaurus arizonensis is from Arizona in North America. No coelophysid fossils were known from Asia until the discovery of Panguraptor lufengensis in 2014 in the Yunnan Province of China. The genus Coelophysis has been found in North America, South Africa, and Zimbabwe.

See also

  • Eucoelophysis, an unrelated silesaurid
  • Pangaea, the supercontinent where coelophysoids originated
  • Timeline of coelophysoid research
  • Toarcian Oceanic Anoxic Event

References

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Sources

  • Rauhut and Hungerbuhler (2000). "A review of European Triassic theropods." Gaia, 15: 75-88.
  • Tykoski, R. S. (2005). "Anatomy, Ontogeny, and Phylogeny of Coelophysoid Theropods." Ph. D dissertation.
  • Yates, A.M., 2006 (for 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.