Dinosaurs first evolved around 240–245 million years ago and the last non‑bird dinosaurs died out about 66 million years ago, so they ruled Earth for roughly 180 million years.

Quick Scoop

When did dinosaurs live?

Scientists group dinosaur time into the Mesozoic Era, split into three main periods.

  • Triassic: About 245–201 million years ago, this is when the earliest dinosaurs appeared and gradually became more common.
  • Jurassic: About 201–145 million years ago, many famous large dinosaurs (and the first bird‑like dinosaurs) thrived.
  • Cretaceous: About 145–66 million years ago, dinosaurs reached huge diversity before most non‑bird species were wiped out by a mass extinction.

In total, non‑bird dinosaurs lived from roughly 245 to 66 million years ago. That means the “age of dinosaurs” lasted three times longer than the time between that extinction and humans today.

How “old” are specific dinosaurs?

Different dinosaur species lived at very different times, often separated by tens of millions of years.

  • Stegosaurus: Lived roughly 155–145 million years ago, in the Late Jurassic.
  • Tyrannosaurus rex: Lived roughly 73–66 million years ago, near the very end of the Cretaceous.
  • Tarbosaurus: A close relative of T. rex, lived about 70–68 million years ago, slightly earlier than T. rex.

So Stegosaurus was already extinct for about 70 million years before T. rex ever appeared. To compare, that gap is longer than the entire time since dinosaurs (except birds) went extinct.

Are any dinosaurs still around?

All non‑bird dinosaurs died out around 66 million years ago in a mass extinction event. However, birds are considered living dinosaurs by most scientists, because they evolved from one group of small theropod dinosaurs.

That means the only dinosaurs alive today are birds, which carry on part of that ancient lineage in modern ecosystems.

Information gathered from public forums or data available on the internet and portrayed here.