Tanycolagreus, meaning “long-limbed hunter,” is a genus of dinosaur from the Oxfordian-Tithonian stages of the Late Jurassic Period of what is now North America. The holotype was discovered in the Bone Cabin Quarry in Albany County, Wyoming, in the Morrison Formation.
The holotype includes a complete skull and mandibles and much of the postcranial skeleton. Two paratypes have also been named — an incomplete hand originally referred to Ornitholestes hermanni, also collected from Bone Cabin Quarry, and a premaxilla, originally referred to Stokesaurus clevelandi, recovered from the Cleveland-Lloyd Quarry of Utah.
Carpenter et al. determined that the holotype of Tanycolagreus represents a sub-adult individual which was about 11 feet long in life. However, one of the paratypes, the premaxilla, would have belonged to a larger individual, measuring up to 13 feet long. It is unclear if the premaxilla fragment represents a fully mature adult, so the upper size limit for the taxon remains unknown.
Though a detailed phylogenetic analysis of Tanycolagreus has yet to be carried out, Carpenter et al. suggest that, based on other known Morrison theropod, the genus most closely resembles Coelurus, though it retains more primitive features. A reconstruction of Tanycolagreus is on display at the North American Museum of Ancient Life in Lehi, Utah, where it is portrayed preying upon a small ornithischian dinosaur, Othnielia rex.