Mammoths are plastic models from a variety of sources. I did some conversion work on the adults' heads, necks and trunks to give many of them more dynamic poses. Cut the head off, repose, pin, then green stuff to redo the neck, trunk and hump. (Then repainted them all.) Worked out pretty well. Cavemen are a mix of Copplestone, Pulp Figures and Reaper, with some modifications to get more variety. Other animals are a mix - horses (repainted from plastic model zebras), megaceros from DeeZee, and the odd cave bear and cave lion from Ral Partha.
In the below pic, the mammoth on the left is an original model. The other three show some of the converted head and trunk poses.