Eomamenchisaurus

Eomamenchisaurus means 'dawn Mamenchisaurus' because it is an early relative of the better-known Mamenchisaurus.1

Its thigh bone (femur) is 1.1 metres (3.6 feet) long, similar to the femur of Mamenchisaurus youngi, which was about 16 metres (52 feet) long.1

The tibia (shin bone) is only about 64% as long as the femur, a primitive feature compared to later sauropods.1

Some of its back vertebrae are fused together, a trait shared with other mamenchisaurid dinosaurs.1

The fourth trochanter (a ridge for muscle attachment on the femur) is on the inner side of the bone, like in early sauropods, not in the middle like in Mamenchisaurus.1

Eomamenchisaurus lived during the Middle Jurassic, about 174 to 161 million years ago.2