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Coelurus
The best specimen referable to this species is dentary with a single tooth still embedded in the jaw. The dentary is long and slender in comparison to the Ornitholestes jaw, which is robust and displays numerous nutrient foraminia.
Marsh, 1879 Kimmeridgian (LJ) of Wyoming, Utah, and ?Colorado Coelurus is known from a good postcranial elements.
Wasn't recognized until 1980, when a study stated that a second species, C. agilis Marsh 1884, was not only the same species but the same individual as the type specimen of C. fragilis. Before this, Coelurus was often confused with Ornitholestes. The type, from a young individual, shows a collection of interesting features, including very long hindlimbs and short but gracile forelimbs. A possible dentary fragment suggests a gracile skull as well. It, along with Tanycolagreus, could be on the line leading to tyrannosaurids.
