This timeline of coelophysoid research is a chronological listing of events in the history of paleontology focused on the coelophysoids, a group of primitive theropod dinosaurs that were among Earth's dominant predators during the Late Triassic and Early Jurassic epochs. Although formally trained scientists didn't discover coelophysoid fossils until the late 19th century, Native Americans of the modern southwestern United States may have already encountered their fossils. Navajo creation mythology describes the early Earth as being inhabited by a variety of different kinds of monsters who hunted humans for food. These monsters were killed by storms and the heroic Monster Slayers, leaving behind their bones. As these tales were told in New Mexico not far from bonebeds of Coelophysis, this dinosaur's remains may have been among the fossil remains that inspired the story. The first scientifically documented coelophysoid taxon was Coelophysis bauri itself. However, when the species was first described by Edward Drinker Cope in 1887, it was thought to belong to a genus of small carnivorous dinosaurs called Coelurus. Later that same year Cope changed his mind and transferred it to the genus Tanystropheus. Tanystropheus turned out to be a long-necked reptile not regarded by scientists as a true dinosaur. As such, "Tanystrophaeus" bauri was soon given its own genus, Coelophysis in 1889. Over the ensuing decades, many new coelophysoids would be discovered, like Podokesaurus, Procompsognathus, and Segisaurus. In 1947, a paleontological team led by Edwin Colbert made a major discovery in New Mexico. While on an expedition to Petrified Forest National Park in Arizona, he made a detour to Ghost Ranch, New Mexico where many phytosaur fossils had been found. There they discovered a massive bonebed preserving hundreds of Coelophysis, many of which were complete and articulated. The find has been considered the most significant Triassic fossil discovery in North America. Later, other coelophysoids and even other bonebeds would be discovered. Notable coelophysoids discovered during the mid to late 20th century include Syntarsus (now Megapnosaurus) and Gojirasaurus. Despite this extensive history of research, the formal recognition of the Coelophysoidea as a distinct group of dinosaurs is relatively recent and the group would not be formally named until a 1994 by Thomas Holtz.
Prescientific
Navajo creation mythology tells stories about the Grey Monsters that populated the world during earth's early days. These monsters came in a variety of forms, including flying and four-footed creatures. They used to terrorize early humans, capturing them and cooking them, in the process leaving behind burnt places in the rocks near Taos, New Mexico. The Navajo believe that the Grey Monsters were wiped out by heroic Monster Slayers and storms. The remains of these monsters can now be found in stones, under tree roots, and near bodies of water. These stories were likely inspired by local fossils, including those of nearby Triassic amphibians and reptiles like Coelophysis, as well as the dinosaurs of the Jurassic Morrison Formation.
19th century
1880s
1884 Othniel Charles Marsh named the Ceratosauria. Coelophysoids would later come to be considered a member of this group for some time.
1887 May 4th: Edward Drinker Cope described the new species Coelurus bauri. Cope transferred Coelurus bauri to Tanystropheus bauri.
1889 Cope described the new genus Coelophysis to house the species Tanystropheus bauri.
1890s
1895 The American Museum of Natural History bought Cope's fossil collection and acquired the original Coelophysis type specimen.
20th century
1910s
1911 Mignon Talbot described the new genus and species Podokesaurus holyokensis.
1913 Fraas described the new genus and species Procompsognathus triassicus.
1915 Von Huene published a detailed description and illustrated the fossils of Coelophysis for the first time in the scientific literature.
1930s
1934 Huene described the new species Halticosaurus liliensternus. He noted that at least two individuals of this species were preserved together.
1936 Camp described the new genus and species Segisaurus halli.
1940s
1947 While en route to collect fossils from Petrified Forest National Park, a team of paleontologists led by Edwin Colbert took a detour to Ghost Ranch, New Mexico where some interesting phytosaur remains had once been discovered. While there they serendipitously discovered a bonebed preserving hundreds of Coelophysis, many of them complete and articulated.
1960s
1969 Raath described the new genus and species Syntarsus rhodesiensis.
1980s
1984 Welles described the new genus Liliensternus to house the species Halticosaurus liliensternus.
1989 Rowe described the new species Syntarsus kayentakatae. He reported that at least three individuals of this species were found preserved together in a single mass burial. Colbert published his findings after 22 years of research on the Ghost Ranch Coelophysis bonebed.
1990s
1991 Hunt and Lucas described the new genus Rioarribasaurus to house the species Coelophysis bauri. They also described the species Rioarribasaurus colberti.
1993 Cuny and Galton informally named the new species Liliensternus airelensis.
1994 Holtz named the Coelophysoidea. He defined them as all theropods more closely related to Coelophysis than to Ceratosaurus. Within the Coelophysoids he defined the Coelophysids as the descendants of the most recent common ancestor shared by Coelophysis and Syntarsus.
1997 Carpenter described the new genus and species Gojirasaurus quayi.
1998 Hunt and others described the new genus and species Camposaurus arizonensis. Sereno redefined Ceratosauria as all neotheropods closer to Coelophysis bauri than to birds. However, this definition never received broad acceptance by the scientific community because the Rowe had already defined the group in 1989, and therefore had priority. He also defined the Coelophysidae as the descendants of the most recent common ancestor shared by Coelophysis bauri and Procompsognathus triassicus. He further divided the family into two stem-based subfamilies; the Coelophysinae (all Coelophysids closer to Coelophysis than to Procompsognathus) and the Procompsognathinae (all coelophysids closer to Procompsognathus than Coelophysis). Tykoski observed that since three species of coelophysoid had been recovered from the Kayenta Formation, this stratigraphic unit preserved the most diverse ceratosaur fauna known to science.
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