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The Mamenxi lizard, Mamenchisaurus (1954)

Phylum : Chordata Class : Reptilia Order : Saurischia Suborder : Sauropodomorpha Family : Mamenchisauridae Genus : Mamenchisaurus Species : M. constructus, M. hochuanensis, M. sinocanadorum, M. youngi, M. anyuensis, M. jingyanensis

Late Jurassic (160 - 145 Ma)

23 m long and 40 000 kg (size)

Sichuan province, China (map)

If it hadn’t been named after the province of China where it was discovered, in 1952, Mamenchisaurus might better have been called “Neckosaurus.” This sauropod (a family of gigantic, herbivorous dinosaurs) wasn’t quite as hefty as more famous cousins like Apatosaurus or Argentinosaurus, but it had the longest neck of any dinosaur of its kind–over 35 feet long, with huge, elongated, numerous vertebrae.

With such a long neck, you might assume that Mamenchisaurus subsisted on the uppermost leaves of tall trees. However, some paleontologists believe this dinosaur didn’t hold its neck vertically, but rather swept it back and forth close to the ground, like the hose of a giant vacuum cleaner. In any event, it’s difficult to imagine Mamenchisaurus having a robust enough metabolism (or a strong enough heart) to enable it to pump blood 35 feet straight up into the air!