Dinosaur classification is the way that scientists determine what are dnosaurs, and how to group them. Find out what different types of dinosaur species there are - and how they are grouped.
Scientists use some basic rules to decide which ancient creatures are dinosaurs. The rules are:
Dinosaurs lived between 250-65 million years ago.
They lived on land.
They had straight legs tucked underneath their bodies.
They were reptiles.
Within these basic rules, scientist group dinosaurs into different categories.
Of the two main types of dinosaurs, the most important difference is in the shape of their hip joints. Dinosaurs with pelvic hips (like lizards) are called Saurischia. The second group, Ornithischia, are those with with hip bones more like birds.
Theropods - meaning 'Beast foot'. They are the only meat-eating group of dinosaurs. They walked on three-toed bird like feet with sharp claws. They had powerful legs and short arms.
Sauropods - lizard footed reptiles. These are the really large herbivores. They walked on all four feet, had small heads and long necks and tails.
Ornithischia - bird hipped
Ornithischia are firstly divided into two groups, with a total of five main subgroups. All of the dinosaurs in this group were herbivores.
Thyreophora
the Stegosaurs (plated or roofed reptiles). These were slow moving medium sized dinosurs that moved on all fours. Their skins were covered in bony plates or spikes.
Ankylosauria (armour covered or 'fused together' reptiles). Small to medium sized dinosaurs. Their bodies were covered in flexible bony armour of slabs or plates.
Cerapods
Ceratopsia (Ceratopsians)- horned face reptiles. Small to large dinosaurs. Some had horned or frilled heads, and some had parrot-like beaks. Usually lived in large herds
Ornithopoda (Ornithopods) meaning bird feet. Small to very large dinosurs that that walked and ran on their two back feet.
Pschycephalosauria - thick headed lizards. Small to medium sized dinosaurs that moved slowly on their back legs. Usually lived in herds.
