Anatomy: Mamenchisaurus was a long-necked giant with a boxy skull and a tiny brain. It was about 70 to 80 feet (21 to 25 m) long, with a 46 foot (14 m) long neck and a 45 foot (<14 m) long tail, but its head was less than 2 feet long. The nostrils were at the top of the head. It had peg-like teeth, but only towards the front of the jaws - there were no teeth in the back of the jaws. Mamenchisaurus weighed only roughly 12 tons (11 tonnes).

When Mamenchisaurus Lived: Mamenchisaurus lived during the late Jurassic Period, from about 156 million to 145 million years ago.

Diet: Mamenchisaurus was an herbivore (a plant-eater). It ate plants, mostly conifers, using its peg-like teeth to pull foliage off plants.

Fossils and Name: Mamenchisaurus was named by Chung Chien Young, a Chinese paleontologist, in 1954. Fossils have been found in China. Mamenchisaurus means "Mamenxi (Ferry) lizard." It was named for the area in which it was found.