Akhoba, head of the Rock Tribe, leads a hunting party. His son Tumak begs the right to his first kill, a small triceratops which he wrestles to death. An elderly man in the party falls from a cliff and is left to die. The party arrives at the Rock Tribe's cave with their prey. The beast is cooked on a fire. When it is done, the strongest feed first, next the women and children, then the few elderly pick the scraps. Tumak defends his portion from demands by Akhoba. They fight and Akhoba knocks Tumak over a cliff as his mother watches. Tumak recovers to find a mastodon attacking him. He runs and climbs a tree. The mastodon rams the tree and knocks it into a river.