Amargosaurus

***Amargasaurus*** (/əˌmɑːrɡəˈsɔːrəs/; "La Amarga lizard") is a genus of sauropod dinosaur from the Early Cretaceous epoch (129.4–122.46 mya) of what is now Argentina. The only known skeleton was discovered in 1984 and is virtually complete, including a fragmentary skull, making *Amargasaurus* one of the best-known sauropods of its epoch. *Amargasaurus* was first described in 1991 and contains a single known species, ***Amargasaurus cazaui***. It was a large animal, but small for a sauropod, reaching 9 to 10 meters (30 to 33 feet) in length. Most distinctively, it sported two parallel rows of tall spines down its neck and back, taller than in any other known sauropod. In life, these spines most likely could have stuck out of the body as solitary structures that supported a keratinous sheath. An alternate hypothesis, now less favored, postulates that they could have formed a scaffold supporting a skin sail. They might have been used for display, combat, or defense.

*Amargasaurus* was discovered in sedimentary rocks of the La Amarga Formation, which dates back to the Barremian and late Aptian stages of the Early Cretaceous. A herbivore, it shared its environment with at least three other sauropod genera, which might have exploited different food sources in order to reduce competition. *Amargasaurus* probably fed at mid-height, as shown by the orientation of its inner ear and the articulation of its neck vertebrae, which suggest a habitual position of the snout 80 centimeters (31 inches) above the ground and a maximum height of 2.7 meters (8.9 feet). Within the Sauropoda, *Amargasaurus* is classified as a member of the family Dicraeosauridae, which differs from other sauropods in showing shorter necks and smaller body sizes. *Amargasaurus* was small for a sauropod, measuring 9 to 10 meters (30 to 33 feet) in length and weighing approximately 2.6 metric tons (2.9 short tons). It followed the typical sauropod body plan, with a long tail and neck, a small head, and a barrel-shaped trunk supported by four column-like legs. The neck of *Amargasaurus* was shorter than in most other sauropods, a common trait within the Dicraeosauridae. Measuring 2.4 meters (7.9 feet) in length, the neck corresponded to 136% of the length of the dorsal vertebral column. This is comparable to *Dicraeosaurus* (123%) but greater than in the extremely short-necked form *Brachytrachelopan* (75%). The neck consisted of thirteen cervical vertebrae, which were opisthocoelous (convex at the front and hollow at the back), forming ball-and-socket joints with neighboring vertebrae. The trunk was made out of nine dorsal and probably five fused sacral vertebrae. The foremost dorsals were opisthocoelous, while the remaining dorsals were amphyplatyan (flat on both ends). Robust transverse processes (lateral projections connecting to the ribs) indicate a strongly developed rib cage. The dorsal vertebrae of *Amargasaurus* and other dicraeosaurids lacked pleurocoels, the deep lateral excavations that were characteristic for other sauropods.

The most striking features of the skeleton were the extremely tall, upwardly projecting neural spines on the neck and anterior dorsal vertebrae. From the third cervical onwards, these neural spines were bifurcated along their entire length, forming a double row. They were circular in cross section and tapered towards their tips. The tallest spines could be found on the middle part of the neck, where they reached 60 centimeters (24 inches) on the 8th cervical. On the neck, they were bowed backwards, projecting above the adjacent vertebra.A similar elongated neural spine has been described from the neck region of the closely related *Bajadasaurus* in 2019. Unlike in *Amargasaurus*, this spine was bowed frontwards and broadened towards the tips.[7] The last two dorsal vertebrae, the hip, and the foremost tail in *Amargasaurus* also had elongated spines; these were not bifurcated but flared into a paddle-shaped upper end. The pelvic region was relatively wide, judging from the long, laterally projecting transverse processes of the sacral vertebrae. The forelimbs were somewhat shorter than the hind limbs, as in related sauropods. Most of the hand and foot bones were not preserved, but *Amargasaurus* probably possessed five digits each as in all sauropods.

Only the rear part of the skull is preserved. It likely showed a horselike, broad snout equipped with pencil-like teeth, as seen in related sauropods for which more complete skulls are known.[9] As in other dicraeosaurids, the external naris (nostril opening) was situated in the posterior half of the skull, diagonally above the orbit (eye opening), which was proportionally large.[6][10] As in most other dinosaurs, the skull featured three additional openings (fenestrae). The infratemporal fenestra, located below the orbit, was long and narrow.[10] Behind the orbit was the supratemporal fenestra, which in dicraeosaurids was uniquely small and can be seen when the skull is viewed from the side. This contrasts with other diapsid reptiles, where these openings were directed upwards, thus being visible only in top view.[2] The antorbital fenestra would have been located in front of the eye opening, although this region is not preserved. An unusual feature were small openings seen on the backside of the skull, the so-called parietal openings or fontanelles. In other tetrapods, these openings are usually seen only in juveniles and would close as the individual grows.[11][12] Skull features shared with *Dicraeosaurus* but absent in most other sauropods included the fused frontal bones and the notably long basipterygoid processes, bony extensions connecting the braincase with the palate.

their are a few living species in equestria, one species is blue with an assortment of red stripes on its body and red sails down its back

another species is yellow and has red sail spikes and back

the last species is grey with a light grey underbelly and black sail spikes and black spots around its eyes