A very big quadrupedal
, herbivorous dinosaur
that lived in the late Jurassic
period. First discovered in China
in the 1950's, its name comes from the area Mamenxi
in which it was found. There are two species
of genus Mamenchisaurus
known: M. constructus
and M. hochuanensis.
Its most distinctive characteristic was its neck, which contained 19 vertebrae and was 15 meters long. The vertebrae themselves were not sufficient to support the bulk of the dinosaur's neck - they were overlapped by long "rib" bones for additional strength. Until the discovery of the Sauroposeidon in the 1990's, Mamenchisaurus had the longest neck of any animal ever known to exist on Earth. The dinosaur's total length was about 25 meters, and its mass has been estimated as upwards of 10 tons. Its head was small and boxy, its body bulky and massive, legs thick and powerful, and tail short and slim in comparison to the enormous neck.