Coelurus fragilis Marsh, 1879

Rauhut, Oliver W. M., 2003, The interrelationships and evolution of basal theropod dinosaurs, Special papers in palaeontology 69, pp. 1-213 : 25

Coelurus fragilis Marsh, 1879

Age . Kimmeridgian-Tithonian.

Occurrence. Morrison Formation, Wyoming, Utah, USA.

Diagnosis. Cervical vertebrae with one or two small, slit-like pneumatic foramina above the parapophyses; pubic boot almost half as long as pubic shafts and strongly convex ventrally.

Remarks. The species Coelurus fragilis was first described by Marsh (1879) on the basis of several vertebrae from Quarry 13 of the Como Bluff outcrop area of the Morrison Formation of Wyoming. The same author later (1884) erected a new species, Coelurus agilis , on the basis of mainly limb and girdle elements from the same quarry. Marsh (1881 b, 1896) furthermore referred material from Quarries 9 and 12 to the same genus (see Ostrom 1980, pp. 255-256, for a list of the material).

Gilmore (1920, pp. 127-129) revised the original material referred to Coelurus fragilis and Coelurus agilis by Marsh. He synonymized Ornitholestes with Coelurus fragilis , which was subsequently accepted by many authors (e.g. Romer 1956, 1966; Steel 1970). The first detailed taxonomic review of Coelurus since Gilmore’ s (1920) paper was carried out by Ostrom (1980), who made a strong case that all the material from Quarry 13 represented a single individual, and thus that Coelurus agilis Marsh, 1884 is a junior objective synonym of Coelurus fragilis Marsh, 1879 b . He furthermore showed that Coelurus is quite different from Ornitholestes and must thus be regarded as a valid taxon. This view has been widely accepted, and it is followed here.