Lizard from La Amarga, Argentina
The early Cretaceous Period, from about 131 to 125 million years ago
South America; Argentina
Amargasaurus was a sauropod from the early Cretaceous period. This plant-eater was weighed roughly 5000 kg. It had 2 rows of spines growing out along its backbone along its neck, body, and tail. These spines may have had a covering of skin forming a sail (or two). If so, this sail might have been a thermoregulatory structure, used to absorb and release heat, for mating and dominance rituals, and/or for making it look much larger than it was to predators. Otherwise, the spines may have been useful as protection. Amargasaurus was a quadruped (it walked on four legs), had a small head, a long neck and a very long tail.