Ah, the amazingly cool-looking Amargasaurus(“La Amarga lizard”)! Only one skeleton is known, found in February 1984 by Guillermo Rougier during an expedition led by the famous Argentine paleontologist José Bonaparte. The skeleton is nearly complete, including a fragmentary skull(sauropod skulls are rarely found complete, if at all), making Amargasaurus one of the best-known sauropods from the Early Cretaceous.
Quite small for a sauropod, Amargasaurus owned two parallel rows of tall spines down its neck and back. While it is unclear how these spines appeared in life, scientists have put forth theories that the spines could have supported skin sails or stuck out of the body as solitary structures supporting a keratin covering. They could have been used for display, combat, or defense.