YANDUSAURUS (YAN-doo-SORE-us)
Period: Middle Jurassic
Order, Suborder, Family: Ornithischia, Ornithopoda, Hypsilophodontidae
Location: Asia (People's Republic of China)
Length: 6 1/2 feet (2 meters)
Yandusaurus, a name meaning "reptile from Yandu," is a very important animal in the history of hypsilophodontid dinosaurs. In the late 1970s and early 1980s, workers found it in the Sichuan Province in the People's Republic of China.
Paleontologists are studying several articulated (the bones are joined) skeletons and skulls of Yandusaurus. It is the earliest known hypsilophodontid and was found in Middle Jurassic rocks. All other hypsilophodontids are from the Late Jurassic, Early Cretaceous, and Late Cretaceous.
This small animal had a short snout, and the back of the skull was high and wide. The spaces for the eyes were large, which might mean that Yandusaurus had good eyesight. It had many small triangular teeth in its jaws. The teeth had ridges on their surfaces, which were similar to the teeth of Thescelosaurus, Parksosaurus, and Zephyrosaurus. The teeth and jaws show that Yandusaurus was a successful plant-eater. It may have also eaten slow-moving insects.
Its neck was long and the body somewhat thinly built. The front limbs were strong with large hands with claws. Scientists do not know whether the hands were able to grasp.
The back limbs were very long and athletic, much like its close relative Orodromeus. Its legs were built for running fast. This running ability must have been how Yandusaurus was able to escape its fierce predators, such as Szechuanosaurus and Yangchuanosaurus. The feet of Yandusaurus also had claws.
The base of the tail is present in only one specimen. The long tail may have acted as a balance for the body while the animal was running. All other ornithopods used their tails for balance. Scientists hope to find more specimens to study.
