Dinosaur species and groups

Dinosaurs were enormously varied, and palaeontologists have named many hundreds of distinct species from fossil remains. These are organised into larger groups based on shared features of their skeletons. The broadest division separates dinosaurs into two main lineages according to the structure of their hip bones: one whose hips resembled those of lizards and another whose hips resembled those of birds. Within these, numerous families evolved a wide range of body forms suited to different ways of life.

Among the best-known groups are the theropods, mostly meat-eating dinosaurs that walked on two legs, a group that includes the large predator Tyrannosaurus rex and many smaller, agile hunters such as the raptors. The sauropods were the giant, long-necked plant-eaters with massive bodies and small heads, including some of the largest land animals known. Other major herbivore groups include the armoured and plated dinosaurs, the horned dinosaurs with bony frills, and the duck-billed dinosaurs. Each group is distinguished by characteristic teeth, limbs, body shape and defensive or feeding adaptations.

Classifying dinosaur species is an ongoing scientific process. New fossils can reveal previously unknown species or show that two named specimens belong to the same animal at different ages. Because soft tissues rarely survive, much of what is inferred about colour, behaviour and relationships is reconstructed from bones and compared with living relatives, especially birds, which descend from small feathered theropods.

Frequently asked questions

How are dinosaurs classified?

They are grouped by shared skeletal features, with a basic division based on hip structure, then subdivided into families such as theropods, sauropods and horned dinosaurs.

What were theropods and sauropods?

Theropods were mostly two-legged meat-eaters, including Tyrannosaurus rex and the raptors, while sauropods were giant long-necked plant-eaters.

How do scientists identify new dinosaur species?

They compare fossil bones with known specimens; distinctive features can indicate a new species, while shared traits may show two finds are the same animal.