Dryptosaurus, the tearing lizard, infamously known as laelaps, is a genus of Tyrannosauroid. Dryptosaurus is one of the first described tyrannosaurs and lived in North ameica. Its hand carried a huge thumb claw and it has been suggested that it might used that claw to attack ankylosaurs by hammering this claw between the armoured and unarmoured part of the body. Don t know if its true, but I read it somewhere. Dryptosaurus was around 7-8 metres long, a quite big tyrannosauroid.