Dinosaur Terms

Order

Dinosaurs are divided into two groups based on hip structure.

Saurischian hip The Saurischia had a hip-bone structure similar to lizards.
Ornithischian hip The Ornithischia had a hip-bone structure similar to birds.

 

Sub-order

Saurischian dinosaurs are divided into two sub-orders:
Therapoda
  • The Theropoda were meat eaters which walked on two legs. They had clawed hands and strong jaws. Theropods were the ancestors of the birds.
  • The Sauropodomorpha were plant eating dinosaurs which walked on four legs. They included the Sauropoda and the Prosuaropoda.
    • The Sauropoda were huge dinosaurs with small heads and long necks and tails.
    • The Prosauropoda were the ancestors of the Sauropods. They were much smaller than the Sauropods..

 

Ornithischian dinosaurs are divided into the following sub-orders:
Thyreophora
  • The Thyreophora were plant eating, armored dinosaurs which walked on four legs. They included the Ankylosauria and the Stegosauria.
    • The Ankylosauria were armored, plant eating dinosaurs which walked on four legs.
    • The Stegosauria were plant eating dinosaurs with armor plates and spikes.

 

Marginocephalia
  • The Marginocephalia were plant eating dinosaurs with horns or thick skulls. They included the Ceratopsia and the Pachycephalosaurs:
    • .The Ceratopsia were plant eating dinosaurs with horns and beaks.
    • The Pachycephalosaurs were plant eating, dome-headed dinosaurs with huge bony skulls.

 

Ornithopoda
  • The Ornithopods were plant eating dinosaurs with no body armor. They included the Iguanadontia.
    • The Iguanadontia were plant eating, beaked dinosaurs with hoof-like claws and a spike on each thumb.

 

 

Period

Dinosaurs lived during the Mesozoic Era (from 248 to 66.4 million years ago). The Mesozoic Era is divided as follows:

  • The Triassic
    • Early (248 to 235 million years ago)
    • Late (235 to 208 million years ago)
  • The Jurassic
    • Early (208 to 178 million years ago)
    • Middle (178 to 157 million years ago)
    • Late (157 to 144 million years ago)
  • The Cretaceous 
    • Early ( 144 to 97 million years ago)
    • Late (97 to 66.4 million years ago).

 Dinosaurs first appeared in the Late Triassic Period.