Crocodile scute fossil
The crocodile belongs to the group of animals called archosaurs, or “ruling reptiles”. Archosaurs are members of a subclass that also includes dinosaurs, and flying repitles, plus several groups of extinct forms, mostly from the Triassic Period (251 million to 200 million years ago).
Crocodiles have a well-developed set of dermal armour plates (scutes) running down their back, between the horny scales of the skin. Not quite scales, not quite bone, or keratin, scutes are layer upon layer of these features, that together compose a sort of armour. The major predator along the sea coast and shallow swamps, these rows of armour plates protected the crocodile from other crocodiles.