Agilisaurus, meaning “Agile lizard”, is a genus of dinosaur from the Middle Jurassic Period of what is now eastern Asia. It was first discovered during the construction of the Zigong Dinosaur Museum, in which it is now housed. There is one named species, A. louderbacki, named after Dr. George Louderback, an American geologist who first recognized dinosaur fossils from the Sichuan Province of China in 1915. The genus and species name was given in 1990, and then further described in 1992. It is known from a almost perfectly complete skeleton. It was only missing a few parts of the left forelimb and hind limb.
Despite being a near complete specimen, this dinosaur has been placed in several different families. It was originally placed in the family Fabrosauridae, which is no longer considered a valid genus by most paleontologists. Recent studies conclude that it may be the most primitive member of the group Euornithopoda. A second species was named by Peng in 1992, but was dismissed as inaccurate in 2005.
Agilisaurus was a small herbivore, about 4 feet in length. It was lightweight and agile. Its lower leg bone was longer than the upper leg bone, which indicates that it was a very quick runner, using its long tail for balance. It may have stood on all fours when browsing for food. It had a beak-like snout used for cropping plant matter.