Birds are Avian Dinosaurs

Super fact 84 : Modern birds are classified as part of the clade Dinosauria. They are direct descendants of small, feathered maniraptoran dinosaurs that survived the Cretaceous-Paleogene extinction event 66 million years ago. Maniraptoran dinosaurs in turn are a major subgroup of coelurosaurian theropod dinosaurs. In other words, birds are avian dinosaurs.

Birds are descendants of specialized maniraptoran theropod dinosaurs that survived the extinction event that killed most dinosaurs 66 million years ago. Maniraptoran dinosaurs in turn are a major subgroup of Tyrannoraptora, which include the well-known Tyrannosaurus Rex. Tyrannoraptora  in turn is a major subgroup of coelurosaurian theropod dinosaurs. Both the well-known dinosaur called velociraptor, and birds belong to the group Maniraptora. Even though the velociraptor was not a bird they shared many bird-like features, including feathers, wishbones, hollow bones, and similar wrist joints.

Birds evolved during the Jurassic period from two-legged, carnivorous, and often feathered dinosaurs, and are the only surviving dinosaurs. They have been classified as avian dinosaurs since the 1980’s. In other words, they are dinosaurs. Initially feathers evolved among dinosaurs for insulation, sexual display, and camouflage rather than flight. One of the early birds was Eoconfuciusornis. It lived 131 million years ago, long before the Cretaceous-Paleogene extinction event 66 million years ago. Eoconfuciusornis could fly and it had colorful feathers.

I brought up this fact in a recent post and I hinted that it was a super fact. It is true, surprising and kind of important. After all birds are all around us. In this post I am exploring the fact that birds are dinosaurs a little bit more than I did in my previous post. Below are a couple of modern birds.

Feathered Dinosaurs

A lot of dinosaurs had feathers, and some could fly. That included many types of dinosaurs other than birds. Dinosaurs with feathers include, for example, Velociraptor, Deinonychus, Archaeopteryx (could fly), Microraptor (could fly), Rahonavis (could fly), Gallimimus, Ornithomimus, Yutyrannus huali, Psittacosaurus, Psittacosaurus, Sinosauropteryx, Sinornithosaurus, Eoconfuciusornis, Wulong, Psittacosaurus, Sciurumimus, Kulindadromeus, Caudipteryx, Utahraptor, Deinonychus, and even young T-Rex and many others. We know that at least some dinosaurs had feathers as well as colors based on fossil finds. Below are some illustrations.

Terror Birds and Other Giant Birds

After the Cretaceous-Paleogene extinction event 66 million years ago birds continued evolving. Some of them became large standing 1 – 3 meters (3-10 feet) and weighing hundreds or even thousands of pounds. From about 53 million years ago until 100,000 years ago there were large birds that we refer to as Terror Birds. They lived at the same time as humans. However, there were other large and scary birds. Dromornis stirtoni was a flightless bird that lived 7-8 million years ago, it was over three meters in height (10 feet) and weighed 500-600 kilograms (1,100 to 1,300 pounds). Below are some illustrations.