The Only Stegosaurus Weapon We Can Prove Was Used

The plates on a Stegosaurus protected nothing. They stood upright along the spine, thin sheets of bone sheathed in keratin, leaving the entire flank of the animal bare. Allosaurus bit pieces off them. The weapon was at the other end. In a quarry in Utah there is an Allosaurus tail vertebra, catalogued UMNH 10781, with a hole punched through it. The shape matches the cross-section of a Stegosaurus tail spike. The bone around the edge healed. The wound itself never did — which suggests part of the spike stayed lodged inside. This is what the plates actually were, what the tail spikes actually did, why one of those is supported by direct fossil evidence and the other still isn't, and why after nearly 150 years nobody has established what those plates were for. New episode every other day. Some visuals in this video are AI-generated reconstructions.