When was the Triassic Period?

The Triassic Period lasted from about 252 to 201 million years ago, roughly 51 million years in total.

What ended the Triassic Period?

A massive volcanic event caused another mass extinction. This wiped out many large reptiles and left dinosaurs as the dominant land animals going into the Jurassic.

What were the first dinosaurs?

Some of the earliest known dinosaurs include Eoraptor, Herrerasaurus, and Eodromaeus, all found in South America. They were small, fast bipeds that lived around 230-235 million years ago.

Home/Prehistoric Periods/Triassic

Triassic Period Pronunciation

How to Pronounce Triassic

try-ASS-ik

ALL CAPS = stressed syllable

252-201 million years ago

The Triassic Period is when dinosaurs first appeared on Earth. After the biggest mass extinction in history wiped out nearly 96% of all species, life slowly rebuilt itself — and dinosaurs emerged as one of the survivors. Early Triassic dinosaurs were small compared to what came later, but they were the ancestors of everything that followed.

Fun Facts

✓The Triassic Period started right after the Permian-Triassic extinction, the worst mass extinction in Earth's history.
✓Earth had one giant supercontinent during the Triassic called Pangaea. There were no separate continents yet.
✓The earliest known dinosaurs appeared about 230-240 million years ago during the Late Triassic.
✓Triassic dinosaurs were much smaller than later giants. Many were no bigger than a modern turkey.
✓The first mammals also appeared during the Triassic Period, though they were tiny and looked like shrews.

Questions About the Triassic

Other Prehistoric Periods

Late Triassic Middle Triassic Jurassic Early Jurassic Middle Jurassic Late Jurassic Middle-Late Jurassic Late Jurassic-Early Cretaceous View all periods →