Archelon

The Archelon is a two-part fossil in the introduced in.

Real-world information
Archelon was a herbivorous marine turtle from the Late Cretaceous period. It is the largest turtle ever known, at up to 4.6 meters in length and weighing up to 2200 kg. It had not a solid shell, but a leathery one supported by a skeletal framework. It lived in the Western Interior Seaway, which went down the middle of modern-day North America, from 80 to 71 million years ago.