Old Earth Ministries Online Dinosaur Curriculum

Free online curriculum for homeschools and private schools

From Old Earth Ministries (We Believe in an Old Earth...and God!)

NOTE:  If you found this page through a search engine, please visit the intro page first. 


Lesson 8 - Coelophysis

Coelophysis, meaning "hollow form" in reference to its hollow bones, is one of the earliest known genera of dinosaur. It was a small, carnivorous biped that lived during the Late Triassic (Norian stage) of the southwestern United States, with scattered material representing similar animals to Coelophysis found worldwide in some Late Triassic and Early Jurassic formations.

The type species, C. bauri, was described by Edward Drinker Cope in 1889. The name Rioarribasaurus is synonymous with Coelophysis. Another dinosaur, Megapnosaurus, is also often considered synonymous with Coelophysis.

Coelophysis: Built for Speed
Videos from Discovery Channel


Quick Facts


Length:  9.8 feet

Height:  3 feet at hips

Weight:  100 lbs

Date Range:  216 - 205 Ma, Norian Age,

Triassic Period


Coelophysis Skeleton

Mounted skeleton at the Cleveland Museum of Natural History (Picture Source)


Coelophysis scale
Coelophysis (purple) scale vs. human (Picture Source)

Coelophysis bauri is known from a number of complete fossil skeletons. C. bauri was a lightly built dinosaur which measured up to 3 metres (9.8 ft) in length and which was more than a meter tall at the hips. The name Coelophysis means "hollow form" or "hollow process", so named because of its hollow limb bones.

Coelophysis was very slim and it probably would have been a fast runner. Despite being an early dinosaur, the evolution of the theropod body form had already advanced greatly from creatures like Herrerasaurus and Eoraptor. The torso of Coelophysis conforms to the basic theropod body shape.

Coelophysis had large eyes and good eyesight. Its neck and head were long. The tail was
Coelophysis head
Artist Impression  (Picture Source)
 also long, and had an unusual structure within its interlocking prezygapophysis of its vertebrae, which formed a semi-rigid lattice, apparently to stop the tail from moving up and down. This may have let the tail act as a rudder or counterweight when the animal was maneuvering at high speeds.

Coelophysis had a long narrow head, and its sharp, curved, jagged teeth show that it ate meat - probably the small, lizard-like animals that were found with it. It may also have hunted in packs to tackle larger prey. Coelophysis had an elongated snout with large fenestrae which helped to reduce skull weight, while narrow struts of bones preserved the structural integrity of the skull. The neck had a pronounced sigmoid curve.


The teeth were typical of predatory dinosaurs, blade-like and recurved with fine serrations on both anterior and posterior edges.

Since knowledge of Coelophysis comes mainly from the specimens excavated at Ghost Ranch, there is a tendency to see this massive congregation of animals as evidence for huge packs of Coelophysis roaming the land. The television series Walking with Dinosaurs, for example, showed small flocks together (and did not cite the Ghost Ranch deposits as evidence). No direct evidence for flocking exists; the deposits only indicate that large numbers of Coelophysis, along with other Triassic animals, were buried together. Some of the evidence from the taphonomy of the site indicates that these animals may have been gathered together to feed or drink from a depleted water hole or to feed on a spawning run of fish, and then became buried in a catastrophic flash flood.

It has been suggested that C. bauri was a cannibal, based on supposed juvenile specimens
Animatronics model demonstrating supposed canibalistic behavior  (Picture Source
 found "within" the abdominal cavities of some Ghost Ranch specimens. However, Rob Gay showed in 2002 that these specimens were misinterpreted (several specimens of "juvenile coelophysids" were actually small crurotarsan reptiles such as Hesperosuchus, and it appears that in some cases bigger individuals were crushed on top of smaller ones), and there is no longer any evidence to support cannibalistic behavior in Coelophysis. Gay's study was corroborated in 2006 in a subsequent study by Nesbitt et al. There may be other evidence coming to light that may show stomach contents from some of these specimens, which might bring greater resolution to the subject.

Two forms of Coelophysis have been found, a more gracile form and a slightly more robust form. Opinion among paleontologists is now that these were female and male variants.

History of discovery


Skeleton at the Natural History Museum, London. (Picture Source)

Below: Two specimens mounted at the Denver Museum of Nature and Science   (Picture Source)


Edward Drinker Cope first named Coelophysis in 1889 during his competition to name species with Othniel Charles Marsh, known as the "Bone Wars". An amateur fossil collector, David Baldwin, had found the first remains of the dinosaur in 1881. The type species, C. bauri was named for Baur, one of the many fossil collectors who supplied Cope. However, these first finds were too poorly preserved to give a complete picture of this new dinosaur.

In 1947, a substantial 'graveyard' of Coelophysis fossils was found in New Mexico, at the Ghost Ranch, close to the original find. So many fossils together were probably the result of a flash flood, which swept away a large number of Coelophysis and buried them quickly and simultaneously. In fact, it seems such flooding was commonplace during this period of the Earth's history and, indeed, the Petrified Forest of nearby Arizona is caused by a preserved log jam of tree trunks that were caught in one such flood. Edwin H. Colbert made a comprehensive study of all the fossils found up to that date, and it is from him that we take most of our information about Coelophysis. The Ghost Ranch specimens were so numerous, including many well-preserved specimens, that one of them has since become the diagnostic, or type specimen, for the entire genus, replacing the original, poorly preserved specimen (see Classification below).

Since the Ghost Ranch specimens were discovered, more skeletons have been found in Arizona, New Mexico and an as-yet unconfirmed specimen from Utah, including both adults and juveniles, the deposits where Coelophysis has been discovered date from the late Carnian to the early Norian faunal stages of the Triassic Period.

Edwin H. Colbert has suggested that Connecticut Valley theropod footprints referred to the ichnogenus Grallator may have been made by Coelophysis.


Coelophysis is a distinct taxonomic unit (genus), composed of a single species, C. bauri.
Coelophysis Skeleton
Skeletal Diagram  (Picture Source

In popular culture

Coelophysis were featured in the BBC television series Walking with Dinosaurs, When Dinosaurs Roamed America and in Dinosaurs Alive (where they hunt an Effigia). The 1974 children's television series Land of the Lost also featured a Coelophysis, nicknamed "Spot".

Coelophysis was the second dinosaur in space. Although Maiasaura had been taken into space three years earlier, a Coelophysis skull from the Carnegie Museum of Natural History was aboard the Space Shuttle Endeavour mission STS-89 when it left the atmosphere on January 22, 1998. It was also taken onto the space station Mir before being returned to Earth.

Coelophysis is also the state fossil of New Mexico.

Return to the Old Earth Ministries Online Dinosaur Curriculum homepage.

horizontal rule

Shopping Results for Coelophysis fossil reproductions

Bay State Replicas - Coelophysis skull (Click on "Fossil Reproductions," then "Skull")