Agilisaurus (AJ-i-li-SAW-rus)
Agilisaurus ('agile lizard') is a genus of ornithischian dinosaur from the Middle Jurassic Period of what is now eastern Asia. The name is derived from the Latin agilis meaning 'agile' and the Greek sauros meaning 'lizard', and refers to the agility suggested by its lightweight skeleton and long legs. Its tibia (lower leg bone) was longer than its femur (upper leg bone), which indicates that it was an extremely fast bipedal runner, using its long tail for balance, although it may have walked on all fours when browsing for food. It was a small herbivore, about 1.2 meters (4 feet) in length, and like all ornithischians, it had a beak-like structure on the ends of both upper and lower jaws to help it crop plant material.
Discovery and history
There is one named species (A. louderbacki), named after Dr. George Louderback, an American geologist and the first to recognize dinosaur fossils from the Sichuan Province of China in 1915. Both genus and type species were named by Chinese paleontologist Peng Guangzhou in very brief fashion in 1990, then described in further detail by Peng in 1992.
A single complete skeleton of A. louderbacki is known to science, one of the most complete small ornithischian skeletons ever found. Only a few parts of its left fore limb and hind limb are missing, and those can be reconstructed from their counterparts on the right side.
This skeleton was actually discovered during the construction of the Zigong Dinosaur Museum, in which it is now housed. This museum features many dinosaurs recovered from the famous Dashanpu Quarry outside the city of Zigong, in the Chinese province of Sichuan, including Agilisaurus, as well as Xuanhanosaurus, Shunosaurus, and Huayangosaurus. This quarry preserves sediment from the Lower Shaximiao Formation (sometimes called "Xiashaximiao") which ranges from the Bathonian through Callovian stages of the Middle Jurassic Period, or from about 168 to 161 million years ago.
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