This is by an artist called LR Roca who was certainly active in the sixties, illustrating for Vampirella magazine, which also featured soem very good cavegirl cover illustrations by Frank Frazetta. I haven't been able to find anything about him (I assume it's a him!) and he doesn't even have a Wikipedia entry. This is a shame as I would have liked to find some other examples of his art as this is a pretty good cavegirl piece.
She has a very good bottom and is definitely wearing a fur bikini. He's done the texture of the fur really well and the only problem I have with it is is that the fur on her bikini bottom looks like it's been stuck onto a normal bikini rather than being more natural. That is a good, hefty-looking stone age spear but again, it probably needs a longer shaft. The creature doesn't look like a dinosaur, more like a Burroughs-type alien lizard so she may be a hollow-earth girl rather than a cave girl. I like this one, though so..
Cavegirl rating 7/10