Dinosaurs Books 61.0

Dinosaurs are a diverse group of reptiles belonging to the clade Dinosauria. They first emerged during the Triassic period, which dates back to between 243 and 231 million years ago. Despite ongoing research concerning their precise origins and evolutionary timeline, dinosaurs soon emerged as the primary terrestrial vertebrates following the Triassic–Jurassic extinction event that occurred around 201 million years ago. Their dominance persisted throughout the subsequent Jurassic and Cretaceous periods. The fossil record suggests that birds are descendants of ancient feathered dinosaurs, evolving from earlier theropods towards the end of the Jurassic Period. Notably, birds stand out as the only surviving lineage of dinosaurs post the Cretaceous–Paleogene extinction event that transpired 66 million years ago. Consequently, dinosaurs are categorized into avian dinosaurs, represented by birds, and non-avian dinosaurs, encompassing all dinosaur species excluding birds. This review will focus primarily on non-avian dinosaurs.