page_title: Coelurus
section_title: Description
hierarchical_section_title: Coelurus / Description
context_page_description: Coelurus is a genus of coelurosaurian dinosaur from the Late Jurassic period. The name means "hollow tail", referring to its hollow tail vertebrae. Although its name is linked to one of the main divisions of theropods, it has historically been poorly understood, and sometimes confused with its better-known contemporary Ornitholestes. Like many dinosaurs studied in the early years of paleontology, it has had a confusing taxonomic history, with several species being named and later transferred to other genera or abandoned. Only one species is currently recognized as valid: the type species, C. fragilis, described by Othniel Charles Marsh in 1879. It is known from one partial skeleton found in the Morrison Formation of Wyoming, United States. It was a small bipedal carnivore with elongate legs.
context_section_description: Coelurus is known from most of the skeleton of a single individual, including numerous vertebrae, partial pelvic and shoulder girdles, and much of the arms and legs, stored at the Peabody Museum of Natural History; however, the relative completeness of the skeleton was not known until 1980. The fossils were recovered from Reed's Quarry 13 at Como Bluff, Wyoming. Additionally, two arm bones possibly belonging to this genus are known from the Cleveland-Lloyd Dinosaur Quarry in Utah. It was not a large dinosaur. Its weight has been estimated at around 13 to 20 kilograms (29 to 44 lb), with a length of about 2.4 meters (7.9 ft) and a hip height of 0.7 meters (2.3 ft). From reconstructions of the skeleton, Coelurus had a relatively long neck and torso due to its long vertebrae, a long slender hindlimb due to its long metatarsus, and potentially a small slender skull.
  The skull is unknown except for possibly a portion of lower jaw found at the same site as the rest of the known Coelurus material. Although it has the same preservation and coloring as the fossils known to belong to the Coelurus skeleton, it is very slender, which may mean it does not belong to the skeleton; this bone is 7.9 centimeters long (3.1 in) but only 1.1 centimeters tall (0.43 in). In general, its vertebrae were long and low, with low neural spines and thin walls to the bodies of the vertebrae. Its neck vertebrae were very pneumatic, with numerous hollow spaces on their surfaces (pleurocoels); these hollows were not evenly distributed among the vertebrae and varied in size. The neck vertebrae were very elongate, with bodies four times longer than wide, and they articulated with concave faces on both ends (amphicoely). The back vertebrae were not as elongate, lacked surface hollows, and had less developed concave faces and bodies that were hourglass-shaped. The tail vertebrae also lacked surface hollows.
  The only bone known from the shoulder girdle is a fragment of scapula. The upper arm had a distinct S-shaped curve in side view and was slightly longer than the forearm (11.9 centimeters [4.7 in] versus 9.6 centimeters [3.8 in]). The wrist had a semilunate carpal similar to that of Deinonychus, and the fingers were long and slender. The only bone known from the pelvic girdle is paired and fused pubis bones, which had a prominent, long "foot" at the end. The thigh bones had an S-shape when viewed from the front. The metatarsals were unusually long and slender, nearly the length of the thigh bones (the best preserved thigh bone is about 21 centimeters long [8.3 in]).
caption: Coelurus compared in size to an average adult human