Dinosaurs are one of the biggest icons, not only in prehistory, but in modern pop culture as well. But what is a dinosaur? Dinosaurs are a diverse group of reptiles that dominated the planet for over 140 million years, first appearing during the Triassic era and losing their prominence after the Cretaceous era. Dinosaurs came in all shapes and sizes. Ranging from the giants such as T. rex, Titanosaurus, and the many varieties of hadrosaurs to the chicken sized and feathered Micro raptor and Archaeopteryx.
Though we often think of dinosaurs as extinct, modern birds are a group of avian dinosaurs that evolved from theropods that survived the mass extinction event 65 million years ago. Being theropods, modern birds still share many similarities with their extinct ancestors. All known Theropods are bipedal, most often with 3 forward facing toes and a single backward facing digit on their feet. Many birds even have scales on their legs!
So, are dinosaurs' reptiles or birds? The short answer is yes. Dinosaurs evolved from a group of early reptiles called Archosaurs. Other non-dinosaur reptiles such as Pterosaurs also split off from this group. Birds, however, evolved specifically from a group of dinosaurs known as Theropods. Because of this ancestry, birds are technically considered reptiles along with all other dinosaurs. In short, all birds are dinosaurs but not all dinosaurs are birds, and both are phylogenetically considered reptiles.