Diapsida is a clade of reptiles characterized by having two temporal fenestrae, which are openings in the skull behind the eyes. This group includes a wide variety of species, such as dinosaurs, crocodiles, and birds. Diapsids are known for their diverse adaptations and evolutionary success, thriving in many environments. The origin of diapsids dates back to the late Carboniferous period, around 300 million years ago. They are distinguished from other reptiles, like anapsids and synapsids, by their unique skull structure. Diapsids have played a significant role in the evolution of reptiles and continue to be an important part of the animal kingdom today.