Mamenchisaurus hochuanensis

Mamenchisaurus had the longest neck of any animal that has ever lived. At up to 11 metres long, the neck was more than half the overall length of the animal, and needed a number of special features to support its weight and length:

• The vertebrae in the neck were unusual because they had long, supporting spines underneath, that overlapped each other,
• The neck vertebrae were hollow and therefore light, like those of a bird,
• Long muscles attached to the middle backbone held the neck in position, and
• The weight of the neck was counterbalanced by the tail.

Mamenchisaurus. Artist: Kate Nolan. Source: Museum Victoria.

Like all sauropods, Mamenchisaurus was a plant-eater, although its small peg-like teeth probably restricted it to a diet of quite soft plant material. The small heads, mouths and brains, and large bodies of sauropods suggest that they were probably ectothermic or 'cold-blooded'. If they had been 'warm-blooded' they would have needed to eat 10 times as much food, and then would have had difficulty in getting rid of waste heat from such large bodies.

The bones used for the cast of Mamenchisaurus in the exhibition at Melbourne Museum were discovered in 1957 by a petroleum exploration team working in Hochuan County of Sichuan Province, western China. Staff from the provincial museum spent several months excavating the nearly complete skeleton, while scientific staff in Beijing removed the bones from surrounding rock and preserved them for further study. The animal was found to be a dinosaur of enormous dimensions: 22 metres in length, 3.5 metres high at the shoulder, with a probable weight of 40-50 tonnes. The head on the specimen displayed is actually a cast of the head of a related dinosaur. A head for this species has only recently been found in China.