The show is set in a primordial Death World, which is 100% Played for Drama, so tragic moments are all around.
Spear and Fang
- The deaths of Spear and Fang's families are nightmarish. Spear and Fang are both visibly shattered by them. Until they turn that grief into pure Unstoppable Rage.
- Spear contemplates suicide after his family got killed.
- The way Spear collapses after the Tyrannosauruses are killed. He's avenged his family but it won't bring them back.
River of Snakes
- The second episode shows that even though he's avenged them, what happened to Spear's family still haunts him, with him making shadow puppets and accompanying noises and thinking he sees, and is entertaining, his kids only for the shadows to become the horned Tyrannosaur Alpha which quickly chases down and eats the shadow versions of his children.
- It's also sad to see Spear and Fang, who bonded strongly in the first episode, get driven apart to the point that Spear attacks Fang.
A Cold Death
- Even before the mammoth is killed by Spear and Fang, it's clear that he's older, and therefore not in good shape: he's missing a tusk and patches of fur, and he gets separated from the herd because he just can't keep up with them.
- The entire episode is filled with moments like this but the ending scene at the Mammoth graveyard is an especially sad one, considering they could only bring back one tusk from the dead herd member, and possibly lost one other when retrieving it.
- Similarly sad is Spear's flashback to the time he taught his son how to hunt, in a scene that clearly mirrors the scene where he and Fang slay the elderly mammoth. Spear is still grieving his family.
- Spear's expression and how he places a hand on the mammoth right before it dies.
Rage of the Ape-Men
- Fang seemingly dying at the hands of the Ape-Men.
- After Spear relapses from his Psycho Serum-induced rage and looks at the corpses of the ape-men he slaughtered, he has a brief My God, What Have I Done? moment.
Plague of Madness
- Spear and Fang watching the diseased Argentinosaurus burn in lava and disintegrate into ashes, the former mournful that they had to kill it. The somber music during this scene sets the sad tone even further.
- The way how the Argentinosaurus is taking in huge gulps of water from the lake after getting infected upon mere seconds, presumably to ease whatever kind of pain he's going through. It's even more saddening when he starts vomiting blood, you can actually hear him screaming in intense agony if you listen hard enough.