Coelophysis: Encyclopedia II - Coelophysis - Description

Coelophysis - Description

Coelophysis bauri is the earliest well known dinosaur. C. bauri was a lightly built dinosaur, between two to three meters in length, and less than a meter tall at the hips. The name Coelophysis means "hollow form" or "hollow process, so named because of its hollow limb bones.

Despite being an early dinosaur, the evolution of the theropod body form had already advanced greatly from creatures like Herrerasaurus and Eoraptor. 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 torso of Coelophysis conforms to the basic theropod body plan, but the pectoral girdle displays some interesting characteristics. C. bauri had a furcula, the earliest known example in a dinosaur. Coelophysis also preserves the ancestral condition of possessing four digits on the hand (manus). It had only three functional digits, the fourth embedded in the flesh of the hand.

The pelvis and hindlimbs of C. bauri are also slight variations on the theropod body plan. It has the open acetabulum and straight ankle hinge that define the Dinosauria. The hindlimb ended in a three-toed foot (pes), with a raised hallux.

The tail of Coelophysis had an unusual structure within its prezygapophysis that formed a semi-rigid lattice, apparently to stop the tail from moving up and down (Gay, 2001). This may have let tail act as a rudder or counterbalance when the animal was maneuvering.

Adapted from the Wikipedia article "Description", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki