What is this old Anime set in prehistoric times?
I believe it is Ryu the Primitive Boy

 


Plot summary from ANN:


  Set in primitive times, a baby with white skin is born into the world. As his skin color is different from the rest of the children around him, the baby is immediately disliked and alienated from the others. Deserted and left on his own, the baby is eventually picked up by an ape called Kitty and raised as her child. The baby, Ryuu, grows up to be a good man but at this moment, his mother is attacked and killed by Tirano. In order to defeat Tirano and also find his real mother, Ryuu decides to set off on his own journey. In the midst of his travels, he meets the siblings Ran and Don. With his new-found companions, Ryuu begins his battle against hardships and obstacles.