As if three-inch teeth don't sound deadly enough, at least one dinosaur may have delivered poison through those chompers. Two paleontologists examining the fossil remains of the Sinornithosaurus, a turkey-size cousin of the velociraptor, noticed it had grooved teeth, much like those on venomous lizards or snakes. Upon closer inspection, they found a cavity in the jawbone that may have held a venom gland, and a channel running from there to ducts near the teeth.
The Sinornithosaurus likely hunted bigger creatures, chewing the poison into their flesh, they speculate. “They grab onto you and they don’t let go,” one of the paleontologists tells NPR. “They just get a vise grip on your hand or whatever and that's enough to get the venom in.” He also says he’s found more fossils with grooved teeth, and thinks other dinosaurs could have similar adaptations. But some skeptics say the features can be interpreted in other, less exciting ways.