Mark of the Beast (S02E17)

After the treehouse is raided by a monkey, Roxton and Marguerite track the culprit to a cave. There, they discover a strange amulet that marks them with a tattoo of a dinosaur skull. This imprint seems to provoke some primal instincts from the explorers as they morph into their more beast-like selves. Overcome by a power that science can't explain, the group begins to exhibit heightened senses. (Prime Video)