Wikipedia
Velocisaurus ("swift lizard") is a genus of ceratosaurian theropod dinosaur from the Cretaceous period of Argentina.
In 1985 Oscar de Ferrariis and Zulma Brandoni de Gasparini uncovered fossils at Boca del Sapo in Neuquén province of Patagonia from layers of the Bajo de la Carpa Formation, dating from the Santonian. Among them was the right lower hind limb of a small theropod. In 1991 this dinosaur was described and named by José Bonaparte as Velocisaurus unicus. The generic name is derived from Latin velox, "swift", a reference to the fact that the hind leg and foot show adaptations for running. The specific name means "unique" in Latin, referring to the exceptional build of the foot.
The genus and species are based on the holotype MUCPv 41. It is part of the collection of the Museo de la Universidad Nacional del Comahue and represents the only known remains of Velocisaurus.
Velocisaurus was probably around long, the tibia having a length of fourteen centimeters. The foot is unique in that the middle (third) metatarsal has become the main weight-bearing element. Its upper end has thickened whereas the shafts of the adjoining second and fourth metatarsals have thinned considerably. Such a configuration is unknown for other theropods, including birds. Bonaparte explained it as an adaptation for a cursorial (running) lifestyle. The high speed would have been necessary to escape larger theropods; Bonaparte suggested that Velocisaurus was itself an omnivore, as indicated by the fact that the sole claw found, of the fourth toe, was not trenchant but relatively straight.
Bonaparte originally assigned Velocisaurus to a family of its own, the Velocisauridae. A study of theropod relationships by Fernando Novas and Sebastian Apesteguia in 2003 showed that Velocisaurus was a close relative of the strange ceratosaur Masiakasaurus. These two may form a subfamily, the Velocisaurinae. In 2004 this subfamily was assigned to the Noasauridae within the more inclusive Abelisauroidea.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 12-foot bones referred to Velocisaurus were examined for signs of stress fracture, but none were found.