The Cretaceous Period
145–66 million years ago · 79 million years long
Flowers, horns, tyrants — and a sudden ending
The short version
The Cretaceous is the longest and most crowded chapter. Flowering plants spread across the world, the continents drifted close to their modern positions, and dinosaurs reached their greatest variety — horned, duck-billed, armoured and tyrannical. Then it ended abruptly, 66 million years ago, with an asteroid impact.
The world then
Gondwana broke apart into South America, Africa, India, Antarctica and Australia; the Atlantic widened and shallow seaways split North America in two.
Sea levels were the highest of the Phanerozoic and the climate peaked in extreme warmth in the mid-Cretaceous, with forests near both poles.
Life in the Cretaceous
Flowering plants appear in the Early Cretaceous and dominate many floras by its end, remaking terrestrial ecosystems and insect life alongside them.
Ceratopsians, hadrosaurs, ankylosaurs and tyrannosaurs dominate the northern continents late in the period, while abelisaurs and titanosaurs hold the south. Birds diversify substantially; pterosaurs decline to a few giant forms.
Inside the Cretaceous
- Early CretaceousFlowering plants appear; feathered fossils of Liaoning.145–100.5 Ma
- Late CretaceousTyrannosaurus, Triceratops; ends at the impact.100.5–66 Ma
Best-documented Cretaceous dinosaurs
Genera whose entire known fossil range sits inside the Cretaceous, ranked by how many sites they turn up at.