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.

3D illustration showing two carnivorous dinosaurs and two large herbivores looking up at a burning asteroid. | Birds are Avian Dinosaurs
Some dinosaurs survived the Cretaceous-Paleogene extinction event 66 million years ago. Shutterstock Asset id: 2196200279 by funstarts33

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.

A colorful velociraptor covered in feather. It does not look like it could fly.
Velociraptor with feathers (well a little bit). Shutterstock Asset id: 2636534673 by Shutterstock AI Generator

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.

A black bird with a long retrix / tail sitting on a tree. | Eoconfuciusornis 130 million years ago. | Birds are Avian Dinosaurs
Eoconfuciusornis 130 million years ago. Nobu Tamura, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons

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.

A shoebill stork is a large gray-blue bird with a huge beak.
A shoebill stork standing at Ueno Zoo, Tokyo, five feet tall. Bob Owen, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons
A taxidermy mount of a turkey standing on our dining room table. | Birds are Avian Dinosaurs
A wild turkey in our dining room.

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.

A Gallimimus dinosaur covered in hair and feathers.
Life restoration showing an adult with feathers, based on those known from the related Ornithomimus. Picture is from here. PaleoNeolitic, CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons
A bird like dinosaur with feathers. It has huge claws.
Life restoration of Pyroraptor olympius. Picture is from here. Mette Aumala, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons.
Birds are Avian Dinosaurs | Reconstruction of the 2014 microraptorine dromaeosaur dinosaur, Changyuraptor yangi. This is a dinosaur with four wings.
Reconstruction of the 2014 microraptorine dromaeosaur dinosaur, Changyuraptor yangi. This is a dinosaur with four wings. The picture is taken from here. Emily Willoughby (e.deinonychus@gmail.com, http://emilywilloughby.com), CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons
Greyish bird like creature with a reptile like head.
Artistic restoration of D. albertensis Artistic restoration of D. albertensis. Picture from here. Fred Wierum, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons
Six dromaeosaurs are shown, all covered with feathers. Microraptor gui (flying), Velociraptor mongoliensis, Austroraptor cabazai, Dromaeosaurus albertensis, Utahraptor ostrommaysorum, Deinonychus antirrhopus. A human is shown on the left. Most of the dinosaurs are bigger than the human.
Size of Utahraptor (5) compared with other dromaeosaurs and a human. It is the biggest one in the picture. The picture is from here. Fred Wierum, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons.

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.

pencil drawing, digital coloring of Paraphysornis brasiliensis, a Terror Bird. | Birds are Avian Dinosaurs
Paraphysornis brasiliensis, a Terror Bird, 8 feet tall weighing 400–530 pounds, this is a terror bird from the Early Miocene of Brazil,: Snowmanradio (talk)Paraphysornis_BW.jpg:  Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0 <https://creativecommons.org/licenses/by/3.0&gt;, via Wikimedia Commons.
The Kelenken, Devincenzia, Phorusrhacos, and Titanis birds are all larger than the human standing on the left hand side. Kelenken guillermoi is the largest.
Size comparison of some phorusrhacids (Terror Birds), including Kelenken, Devincenzia, Phorusrhacos, and Titanis. Picture taken from here. PaleoNeolitic, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0&gt;, via Wikimedia Commons.
A flightless bird with huge yellow beak. | Birds are Avian Dinosaurs
A pencil-drawn reconstruction of Dromornis stirtoni. Picture is taken from here. Nobu Tamura (http://spinops.blogspot.de), CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons

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Author: thomasstigwikman

My name is Thomas Wikman. I am a software/robotics engineer with a background in physics. I am currently retired. I took early retirement. I am a dog lover, and especially a Leonberger lover, a home brewer, craft beer enthusiast, I’m learning French, and I am an avid reader. I live in Dallas, Texas, but I am originally from Sweden. I am married to Claudia, and we have three children. I have two blogs. The first feature the crazy adventures of our Leonberger Le Bronco von der Löwenhöhle as well as information on Leonbergers. The second blog, superfactful, feature information and facts I think are very interesting. With this blog I would like to create a list of facts that are accepted as true among the experts of the field and yet disputed amongst the public or highly surprising. These facts are special and in lieu of a better word I call them super-facts.

52 thoughts on “Birds are Avian Dinosaurs”

  1. A fascinating post, Thomas. My husband talks about birds coming from dinosaurs but it was so interesting to learn exactly how and the many different types of dinosaurs related to birds. The reconstruction images are spectacular and wow, they were big!

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    1. Thank you so much Annika. Yes, not only are birds and dinosaurs related, birds are dinosaurs. Now a day they classify birds as a clad of dinosaurs. So calling birds dinosaurs is technically correct. Yes after the other dinosaurs died out some birds got really big. Meeting a 10 feet 1000 pound bird in the forest would have been frightening, and yet that was a possibility for early humans and Neanderthals.

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    1. Yes I agree with you. Terror Birds still existed just 100,000 years ago. I certainly would not like to meet a Dromornis. Like you say some birds can still be a bit scary like the bald eagles you mention, and I’ve been attacked by angry swans and seagulls.

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    1. Thank you so much Ada. Yes what a huge and scary bird Dromornis was. They are illustrations and it is hard to know how accurate they are but hopefull at least the body shape and size is correct. In some cases pigmentation left behind helps us know the color.

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    1. Thank you so much for your kind words Esther. Even though this post was not an answer to your prompt it was inspired by my response to your prompt (flying). Your prompts are gifts that keep on giving. Thank you for doing them.

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    1. I agree the Ornithomimus looks strange, and it is big and could not fly. The’ve found a lot of feathered dinosaur fossils as well as ancient birds. I just selected a few. Thank you so much for your comment and kind words Robbie.

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  15. This is one of those facts that sounds surprising at first and then feels completely obvious once you see the evolutionary path laid out so clearly. I appreciate how you walk through the classification step by step — from maniraptorans to modern birds — while keeping it accessible and engaging. The feathered reconstructions really bring the science to life.

    What makes this especially fun is the shift in perspective it creates. Looking at everyday birds and realizing they are technically dinosaurs adds a fresh sense of wonder to something so ordinary. It’s a reminder that the ancient world is not as distant as we sometimes imagine.

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    1. Thank you so much for checking it out Di. The natural history of birds have certainly been updated since when we were young. To think that what is essentially a dinosaur may be flying by right now. I agree it is fascinating.

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        1. Yes once I found this out, and about the reclassification of birds, and the feathered dinosaur ancestors, such as velociraptor and utahraptor, that I thought had scaly lizzard skin (but NOT) I am also looking at birds differently.

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