Amargasaurus

Amargasaurus is an extinct genus of sauropod dinosaurs from the Early Cretaceous period and measuring up to 10 meters (33 feet) long. A distinctive feature of this dinosaur is the pair of parallel rows of tall spines down its neck and back, taller than in any other known sauropod. It is an example of Convergent Evolution; with thyreophoran-like, almost spinosaurian dorsal, cervical, and caudal vertebral spines.

Amargasaurus was first discovered in 1984 in Argentina, in La Amarga formation, by the same expedition which also uncovered the single but extremely well-preserved Carnotaurus specimen.[1] Living about 125 million years ago (and thus being far older than Carnotaurus), this is one of the few Cretaceous sauropods known from a complete skeleton. It is also one of the smaller sauropods, as, despite reaching up to 10 meters in length, most of that was neck and tail, and the animal wouldn’t be much heavier than a modern rhino. The distinctive row of spines along its neck has been the subject of considerable debate among palaeontologists, with some theorizing that it was used for thermoregulation, while others believe they protected the animal from predators.

Amargasaurus was a member of the Dicraeosauridae family, related to Rebbachisaurids such as Nigersaurus and diplodocids such as Diplodocus and Apatosaurus. While not closely related to the giant titanosaurs such as Dreadnoughtus, Amargasaurus was a close relative of Maraapuniasaurus, one of the largest dinosaurs from the Jurassic, known from a giant vertebra long lost to the elements.

In 2022, recent analyses have shown that Amargasaurus is unlikely to have had sails in life, due to it restricting its neck movement.