Archosauromorphs

Archosauromorphs are a major clade of diapsid reptiles that includes living birds and crocodilians, as well as extinct groups like dinosaurs and pterosaurs. The group is defined by a set of skeletal features, including a hole in the skull in front of the eye socket (the antorbital fenestra). Archosauriformes is a more inclusive clade that includes Archosauria and their closest extinct relatives.

The earliest archosauromorphs appeared in the Late Permian period. By the Triassic, they had diversified into a wide range of forms, from small, lizard-like creatures to large, herbivorous and carnivorous animals. The most well-known archosauromorphs are the dinosaurs, which dominated terrestrial ecosystems for over 160 million years. Birds are the direct descendants of one lineage of theropod dinosaurs. Crocodilians, the other living archosauromorph group, are also descended from archosaurian ancestors.

Archosauromorphs exhibit a broad spectrum of lifestyles and diets. Some were bipedal or quadrupedal, while others could switch between the two. Their diets ranged from herbivory to carnivory and omnivory. The evolution of archosauromorphs is marked by several key innovations, including the development of more efficient lungs, changes in limb structure that allowed for more upright posture, and the evolution of specialized dentition for processing different types of food.

The extinction of the non-avian dinosaurs at the end of the Cretaceous period, caused by an asteroid impact and subsequent environmental changes, dramatically reshaped the archosauromorph landscape. However, birds survived and subsequently diversified, becoming the dominant aerial vertebrates. Crocodilians also survived, albeit in reduced numbers compared to their Mesozoic heyday, and continue to inhabit aquatic and semi-aquatic environments. The study of archosauromorphs provides crucial insights into reptile evolution, paleontology, and the history of life on Earth.