Turtles

The largest turtle known so far was Archelon ischyros.

An excerpt from the article 27 facts about turtles

The body length of this marine giant was as long as 4.5 m and its weight was about 2.2 t. It lived at the end of the Cretaceous about 75 to 65 million years ago. It is possible that this turtle survived the extinction of the dinosaurs and its extinction was linked to the appearance of new species of marine animals and mammals feeding on its eggs.