The diapsids, the reptile subclass that was destined to be the most important, started off as a small group of specialized climbing and gliding animals. Some appear to have been very agile tree-living animals, which has led to their classification as the order Simiosauria, the “monkey lizards”.
When discovered, Cosesaurus caused a scientific stir. The skeleton seemed to be surrounded by plumes of some sort which have been interpreted as feathers. Several scientists see this as indicating that Cosesaurus was ancestral to the birds. However, the consensus is now that these plumes weremarks in the rock formed as Irhe rock was split. animatronic dinosaur
Features: In build, Cosesaurus is lizard-like. The mam difference between it and a lizard is in the structure of the hips, which are broader than usual and accommodate more than the usual number of vertebrae. This suggests an ability to walk or run on its hind legs. The muscle scars on the arm bones and the breast-bone show that it could pull its arms together strongly. This has been interpreted as an adaptation to climbing.