This is just an oddball variant Teenage Mutant Ninja Turtle. Variant Ninja Turtles were all over the place in their heeyday - a staple of Playmate's toy marketing strategy. But few were as odd as prehistoric turtles! Because the oddness didn't stop at cavemen themed outfits- originally, each prehistoric turtle came with a dinosaur ride/pet too!
Sadly all I have is Donatello in a sabretooth skin.
But I have to admit he's pretty darn cool!
One could imagine a storyline that throws Donatello out of time and into pre-history. Forced to survive with only his wits to aid him, he eventually battles and subsequently carves up and eats a sabretooth cat ; later using the skin to keep warm at night.