Yunnanosaurus, meaning “Yunnan lizard,” is a genus of prosauropod dinosaur from the Early to Mid Jurassic Period. This was perhaps one of the last living prosauropods of the time. It was discovered by Yang Zhongjian in the Lufeng Formation of Yunnan, China. The find consisted of twenty incomplete skeletons, including two skulls, and were excavated by Tsun Yi Wang.
The type species, Y huangi, was named by C.C. Young in 1942, and created the family Yunnanosauridae based on the findings as a unique specimen. The family comprises only the one genus, Yunnanosaurus. A second species, Y. robustus, was also named by Young in 1951, but this species has since been included in the type species. The confusion stemmed from the fact that the original finds were of juvenile specimens and the later find was that of an older dinosaur.
In 2007, another species Yunnanosaurus, Y. youngi, was named by Lu and colleagues honoring C.C. Young.
Based on two valid species, the adult Yunnanosaurus ranged in size from 23 feet to 42 feet long and up to 7 feet tall.
Yunnanosaurus was unique among prosauropods as its jaws, containing more than sixty spoon-shaped teeth, were self-sharpening because they wore against each other as the animal fed. Experts believe the teeth were advanced compared to other prosauropods, as they shared features with sauropod.
However, scientists do not consider Yunnanosaurus to be closely related to sauropods because the rest of its body is distinctly prosauropod in design. The similarity in the teeth of Yunnanosaurus and sauropods may be an example of convergent evolution.