⌛ Dinosaur Eras Timeline

Dinosaurs Through Time: Triassic, Jurassic, Cretaceous

The Age of Dinosaurs spans three geological periods — Triassic (252–201 million years ago), Jurassic (201–145 million years ago), and Cretaceous (145–66 million years ago). Each period had different climates, landmass arrangements, plant life, and dominant dinosaur species. This interactive timeline lets students explore the progression of dinosaur evolution across these three eras and understand how Earth itself changed during the 186 million years of dinosaur dominance.

Placing dinosaurs in time is important because many popular culture depictions show species together that actually lived millions of years apart. Stegosaurus and Tyrannosaurus rex never met — Stegosaurus went extinct 80 million years before T. rex evolved. In fact, T. rex lived closer in time to us than to Stegosaurus. Understanding these timescales develops the concept of deep time that is fundamental to geology and evolutionary biology.

How Earth Changed

During the Triassic, all continents were joined as the supercontinent Pangaea. By the Jurassic, Pangaea had begun to split apart. By the late Cretaceous, the continents were approaching their modern positions. This continental drift affected climate, ocean currents, and which dinosaur species could interact — dinosaur evolution and plate tectonics are deeply intertwined stories.

The timeline culminates with the Cretaceous-Paleogene extinction event (66 million years ago), when an asteroid impact and volcanic eruptions wiped out roughly 75% of all species, including all non-avian dinosaurs. This catastrophic event reset life on Earth, allowing mammals — and eventually humans — to diversify into the ecological roles dinosaurs had dominated. Understanding this extinction helps students appreciate both the fragility and the resilience of life on Earth.

Last reviewed: May 2026 · Aligned with NGSS 3-LS4-1, MS-ESS1-4