Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
dinosaur
References & Edit History Quick Facts & Related Topics
Images, Videos & Interactives
Illustration showing various dinosaur species drawn to scale and grouped by geologic era: Late Cretaceous, Early Cretaceous, Jurassic, and Triassic. Dinosaurs range from large species like Brachiosaurus and Tyrannosaurus to smaller ones like Velociraptor and Compsognathus, with a human silhouette included for size comparison. Measurement bars at the bottom indicate 1 meter and 3 feet for scale reference. dinosaur phylogeny
Did Dinosaurs Really Have Feathers?
Dr. Jingmai O'Connor smiles and gestures toward a fossil of Archaeopteryx on display at the Field Museum, with exhibit text visible in the background.
Dinosaur National Monument fossil
Person in inflatable T. rex costume lifting small dumbbells in a gym beside a weight rack; text overlay reads “design flaw?” with an arrow pointing to the T. rex's arms.
The origins of birds.
Silhouette of a bird with outstretched wings holding a Hello, my name is ? badge, next to a set of four large, weathered bones on a dark background.
Illustration of Plateosaurus, a large, long-necked herbivorous dinosaur from the late Triassic period, shown in profile with a human and dog for scale. The Plateosaurus stands on four legs, highlighting its long tail and neck, and may have reared up to reach high vegetation. Scale bars indicate 1 meter and 3 feet, and text notes its length of 26 feet and European origin.
At a Glance
default image
dinosaur summary
Quizzes
Sea otter (Enhydra lutris), also called great sea otter, rare, completely marine otter of the northern Pacific, usually found in kelp beds. Floats on back. Looks like sea otter laughing. saltwater otters
Animal Group Names
Lion (panthera leo)
Deadliest Animals Quiz
Young chimpanzee dressed in a shirt and sweater vest, scratching his head thinking. (primates)
Wild Words from the Animal Kingdom Vocabulary Quiz
Mute swan with cygnet. (birds)
Match the Baby Animal to Its Mama Quiz
Model of a molecule. Atom, Biology, Molecular Structure, Science, Science and Technology. Homepage 2010 arts and entertainment, history and society
Science Quiz
Related Questions
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
Britannica Websites
Articles from Britannica Encyclopedias for elementary and high school students.
Illustration showing various dinosaur species drawn to scale and grouped by geologic era: Late Cretaceous, Early Cretaceous, Jurassic, and Triassic. Dinosaurs range from large species like Brachiosaurus and Tyrannosaurus to smaller ones like Velociraptor and Compsognathus, with a human silhouette included for size comparison. Measurement bars at the bottom indicate 1 meter and 3 feet for scale reference.
dinosaurs to scale A selection of dinosaurs grouped by the geologic interval in which they lived.

dinosaur

fossil reptile
Also known as: Dinosauria
Written by
John H. Ostrom
Emeritus Professor of Geology, Yale University; former Curator of Vertebrate Paleontology, Peabody Museum of Natural History. Coauthor of Marsh's Dinosaurs: The Collections from Como Bluff.
John H. OstromAll
Fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
Britannica Editors
Last updated
•History

dinosaur, (clade Dinosauria), the common name given to a group of reptiles, often very large, that first appeared roughly 245 million years ago (near the beginning of the Middle Triassic Epoch) and thrived worldwide for nearly 180 million years. Most died out by the end of the Cretaceous Period, about 66 million years ago, but many lines of evidence now show that one lineage evolved into birds about 155 million years ago. (Read E.O. Wilson’s...

Discover the world with Britannica

Subscribe to Continue Reading

Free Trial | No Ads | Exclusive Content
Explore Subscriptions
DNA
Right
Mobile