Dinosaur with sails on it's neck !!

Group Sauropoda.

Sauropods were a type of dinosaur with a long neck that lived on an herbivorous diet. Sauropods possessed long necks and tails, short heads (in comparison to the rest of their body), and four strong, pillar-like legs. Some species have grown to massive proportions, and the group contains the largest animals to have ever lived on land. Sauropods thrived in the prehistoric world as the biggest and largest terrestrial animals that ever lived, from the Jurassic period through the end of the dinosaur era.

Discovery of the long necked.

Paleontologists in Argentina discovered a nearly complete fragmented skull in 1984. The skull belonged to a sauropod dinosaur that was not as large as its relatives. Because the skull is nearly complete, scientists can get a good picture of the animal's body structure. This animal existed 122 million years ago in the wood lands of south America, during the early Cretaceous period. (The early cretaceous period was around 145-100years ago) The dinosaur was given the name Amargasaurus cazaui by scientists. The skull was discovered in the Argentinian La Amarga formation, hence the name means "la Amarga lizard."

Source: http://dinosaurios.org/wp

They are bit different from their relatives.

Amargasaurus, unlike other sauropods, was 30-33 feet long and weighed 2.6 tons. It had a long tail and neck, a small skull, and a barrel-shaped trunk supported by four column-like legs, as is typical of sauropods. Amargasaurus had a shorter neck than most other sauropods. As a result, Amargasaurus was assigned to the Sauropod family Dicraeosauridae. Dicraeosauridae is a sauropod family with a short neck and a small body size. The Amargasaurus’ most amazing feature is its enormously tall, upwardly extending neural spines on the neck and all the way back. This double row of spike-like neural spines was bifurcated along its entire length. They had a circular cross section and tapered to the points. The tallest spines were located in the middle of the neck, reaching 60 centimeters

What are the uses of the unusual sail.

The spines of the Amargasaurus could be used to deter predators, they may have had some kind of role in temperature regulation (that is, if they were covered by a thin flap of skin capable of dissipating heat), or, most likely, they may simply have been a sexually selected characteristic (Amargasaurus males with more prominent spines being more attractive to females during mating season.

source:https://dinosaurpictures.org/Amargasaurus-pictures

Latest information about spines.

According to the 2014 study, the average resting posture of the Amargasaurus head would place it just under 1 meter off the ground, but it could rise as much as 2.7 meters above the ground when the neck was lifted and the neural spines compressed. However, that knowledge was acquired before to the 2022 publication describing the spines as being supported by ligaments, and with that extra soft tissue, Amargasaurus may not have been able to elevate its head as far as originally supposed. A limited range of motion in the neck would have been conceivable, although to a lesser extent. Dicraeosauridae sauropods are already thought to be slow browsers. A feeding niche that would allow sauropod dinosaurs like Amargasaurus to escape direct competition with the rising varieties of larger titanosaurs found in South America.