Amphicoelias fragillimus

Amphicoelias fragillimus - Possibly one of the largest land animals to ever walk the Earth

Temporal range: Late Jurassic, Tithonian, around ~150 Ma

Probable length: Between ~40-60 metres?
Probable mass: Between ~100-200 tonnes?

Etymology: Fragile double hollow


Amphicoelias fragillimus was a gigantic gigapod, or very large sauropod, that lived on North America during the Late Jurassic. It was possibly among the largest land animals to have ever walked the Earth.

The type specimen of the smaller Amphicoelias species, Amphicoelias altus, AMNH 5764, was discovered by palaeontologist Edward Drinker Cope in December 1877 (though not published until 1878) for an incomplete skeleton consisting of two vertebrae, a pubis, and a femur. Later in 1878, Cope discovered and described a larger specimen, AMNH 5777, which was known from a partial neural arch approximately ~1.5 metres tall. He assigned it to a second species, A. fragillimus. This was likely the largest dinosaur specimen known from skeletal remains ever to be discovered. The neural arch was badly preserved and crumbling and was soon discarded, probably by Cope himself.

In 2006, Kenneth Carpenter estimated A. fragillimus at ~58 metres long and ~122.4 tonnes based on Greg Paul's Diplodocus.
______________

UPDATE(11/5/2016): A complete remake
Previous version