Mamenchisaurus (mah-MUN-chee-SAW-rus, (External Link) or spelling pronunciation ) was a plant-eating four-legged dinosaur, known for its remarkably long neck which made up half it's total length. Most species lived 145 to 150 million years ago, in the Tithonian age of the Late Jurassic Period of China. Discoveries Mamenchisaurus was first discovered in 1952 on the construction site of the Yitang Highway in Sichuan, China. The partial skeleton fossil was then studied, and named Mamenchisaurus c… (More on Mamenchisaurus)