Amargasaurus

Amargasaurus was a sauropod from the early Cretaceous period. It grew to 10 meters (33 feet) length, which was relatively small for a sauropod. It was a quadrupedal herbivore with a long, low skull on the end of a long neck, much like its relative "Dicraeosaurus".
"Amargasaurus" was found in La Amarga, a canyon in Neuquén Province, Argentina.
Features.
"Amargasaurus" had two tall rows of spines on top of its backbone along the neck and back. The function of the spines is not known. They may have operated as a defence from theropod attack from above. Another idea is that they supported a sail-like structure.
The 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 cm on the 8th cervical. On the neck, they were bowed backwards, projecting above the adjacent vertebra. Greatly elongated spines continue along the last two dorsal vertebrae, the hip and foremost tail. However, in these regions the spines were not bifurcated but flared into a paddle-shaped upper end.