Coelophysis is a small (up to 9.8 feet/3 meters long) theropod dinosaur. Its large eyes, long neck, long tail, large and clawed hands and slender and narrow hind foot are among its distinctive features. It also has more than 100 pointed, blade-like serrated teeth in its skull and lower jaws.
The shape of the hip joint of Coelophysis indicates that the hindlimb was held under the body in an upright posture, and this identifies Coelophysis as a dinosaur.
Coelophysis has many features that are distinctive of the meat-eating dinosaurs, the Theropoda. These include: a large lachrymal bone of the skull in front of the eyes, a clawed hand, five vertebrae in the sacrum, a “boot” (thickened bone area) on the tip of the pubic bone, a bowed femur (thigh bone), and a narrow hind foot with three functional toes.
The presence of fused bones in the hind leg, especially in the ankle, are distinctive of ceratosaurs, the groups of theropods that includes Coelophysis.
Particularly distinctive features of Coelophysis among ceratosaurs are in its pelvis, which shows a high degree of fusion of the bones and a distinctive opening (for blood vessels and nerves) in the pubic bone.