Yunnanosaurus
| Key | Value |
|---|---|
| Name Meaning | “Yunnan lizard” |
| Location | China (Yunnan) |
| Time Period | c. 190 million years ago (Early Jurassic) |
| Length | 35 ft (10.5 m) |
| Weight | 1.5 tons (1,360 kg) |
| Locomotion | Biped (?) |
| Diet | Herbivore |
| Described | 1942 (Young) |
| Geological Formation(s) | Lufeng, Fengjiahe |
| Valid Species | Yunnanosaurus huangi (type), Yunnanosaurus youngi, Yunnanosaurus robustus (?) |
Phylogeny: Dinosauria > Saurischia > Sauropodomorpha > Plateosauria > Massopoda > Sauropodiformes > Yunnanosauridae
Overview: Yunnanosaurus takes its name from the southern Chinese province of Yunnan, where its holotype specimen was discovered back in 1939. Yunnan was among the Chinese regions more or less safe from the ongoing Japanese invasion at that time. The description of Yunnanosaurus was published in 1942 by the renowned Yang Zhongjian, alternatively known as C. C. Young, considered to be one of the founders of modern vertebrate paleontology in China. Yang had a decent amount of material to work with when it came to Yunnanosaurus. Recovered fossils included much of the spine, a complete pelvis, most of the legs, many arm bones, the upper portion of the tail, some of its neck vertebrae, and a complete skull. More fossils would be found in the following decades. In the 1950’s, a second species called Yunnanosaurus robustus was described, but it’s probably based on adult fossils of the type species. Yunnanosaurus youngi, named in 2007, is likely valid, however.
The basic body plan of Yunnanosaurus was fairly typical for a basal sauropodomorph. It was a biped, though some restore it as capable of quadrupedal movement. While up on its hind limbs, the arms were free to be used for foraging and defense, using its large claws. The neck was fairly long, while the skull was tiny. Yunnanosaurus had relatively simple teeth, but they do seem to have been more specialized than those of some earlier sauropodomorphs, being self-sharpening, well suited to tear and shear plant material. One other notable trait was its potential size. The genus’s type species, Y. huangi, was an average to large-sized “prosauropod” itself, but Yunnanosaurus youngi appears to have been remarkably large for such an animal. Bigger individuals of this species grew to be ten to twelve meters long or possibly even longer. It was among the largest of the sauropodomorphs to retain the ability to walk bipedally, but it was also among the last of such dinosaurs.