Why, despite looking like lizards, dinosaurs aren’t lizards
While both dinosaurs and lizards look similar and belong to the reptile family – and the word dinosaur stems from the Greek for ‘terrible lizard’ – dinosaurs aren’t lizards.
Dinosaurs belong to a group called Archosauria, which also includes crocodilians and birds. Lizards, on the other hand, belong to a different group known as Lepidosauria, which also includes snakes and the tuatara.
Lepidosaurs and archosaurs share a common ancestor, but they diverged early in the Mesozoic Era, likely during the Triassic period, over 230 million years ago. While lizards and dinosaurs both evolved from earlier reptiles, their evolutionary paths branched off long before dinosaurs came to dominate the Earth.
What’s the difference between dinosaurs and lizards?
This distinction is based on anatomical features, notably the legs.
A lizard’s legs stick out at right angles from its body, producing a sprawling stance, whereas a dinosaur’s legs are tucked underneath.
Why do lizards run on two legs?
Keeping a big reptile upright requires strong joints between the hips and backbone, which the ancestors of dinosaurs made by fusing together vertebrae to form a modified structure – the sacrum.
Discover more fascinating facts about the dinosaurs
- Dinosaur teeth: what were they like, how ferocious were they – and what do they tell us about a dinosaur’s diet?
- Were dinosaurs good parents – and how on earth do we know?
- Dinosaur sex: how these huge animals mated with all those dangerous spikes, claws and plates