Types of Dinosaurs: How Scientists Classify Them
Scientists organize dinosaurs into groups based on their anatomy, especially their hip structure. Understanding these categories helps make sense of dinosaur diversity.
Learn more in our Dinosaurs Explained collection →
The Two Main Groups
All dinosaurs belong to one of two major groups based on hip structure:
Saurischia ("Lizard-Hipped")
Hip bones arranged like lizards. Includes:
- T. Rex, Velociraptor, Spinosaurus
- Also includes birds!
- Brachiosaurus, Diplodocus, Brontosaurus
Ornithischia ("Bird-Hipped")
Hip bones arranged like birds (ironically, birds evolved from lizard-hipped dinosaurs).
- Triceratops, Stegosaurus, Ankylosaurus
- Hadrosaurs (duck-bills)
- Iguanodon
Dinosaur Types by Diet
Carnivores (Meat-Eaters)
- Large: T. Rex, Giganotosaurus, Spinosaurus
- Medium: Allosaurus, Carnotaurus
- Small: Velociraptor, Deinonychus, Compsognathus
- Walked on two legs
- Sharp teeth and claws
- Forward-facing eyes
- Many had feathers
Herbivores (Plant-Eaters)
- Brachiosaurus, Diplodocus, Argentinosaurus
- Largest land animals ever
- Triceratops, Styracosaurus
- Beaks and frills
- Ankylosaurus, Euoplocephalus
- Bony armor, tail clubs
- Stegosaurus
- Plates and tail spikes
- Parasaurolophus, Edmontosaurus
- Often with elaborate crests
Dinosaur Types by Size
Giants
- Argentinosaurus — 70-100 tons
- Patagotitan — 70+ tons
- Brachiosaurus — 30-60 tons
All were sauropods.
Mid-Sized
- T. Rex — 9 tons
- Triceratops — 6-12 tons
- Stegosaurus — 5-7 tons
Small
- Velociraptor — 33 lbs
- Compsognathus — 6 lbs
- Microraptor — 2 lbs
Dinosaur Types by Locomotion
- All theropods
- Many ornithischians (hadrosaurs, etc.)
- All sauropods
- Ceratopsians, ankylosaurs, stegosaurs
- Some could switch (Iguanodon)
Special Categories
Feathered Dinosaurs
- All birds (which are dinosaurs)
- Velociraptor
- Microraptor
- Possibly T. Rex (debated)
Armored Dinosaurs
- Ankylosaurs — Full body armor, tail club
- Stegosaurs — Plates and spikes
- Ceratopsians — Neck frills, horns
Crested Dinosaurs
- Parasaurolophus — Tubular crest
- Dilophosaurus — Twin crests
- Corythosaurus — Helmet-like crest