mention a few of its physical appearance?
It has a long tail and neck, a small head, and a barrel-shaped trunk supported by four column-like legs.
Amargasaurus
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. 
what is amargasaurus? A genus of sauropod dinosaur when was it discovered? 1984
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Amargasaurus [SEP] Description
"Amargasaurus" was small for a sauropod, measuring in length and weighing approximately . 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 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.