Key Events

• Dinosaurs continue to dominate.
• Flowering plants appear.
• New groups of mammals and birds evolve.
• The Cretaceous Period and Mesozoic Era end when an asteroid hits Earth at Chicxulub in Mexico.
• A fast-moving cloud of dust, soot from wildfire and other ejecta material spreadsaround the globe in 4-5 hours. The Earth becomes dark and cold for about a decade, with longer-term changes lasting much longer (decades, or even hundreds of years).

Facts, Debates & Trivia

• The Cretaceous Period is named after the Latin for chalk, creta.
• Cretaceous rocks can be found in many places of the world.
• The impact of a ~10 km diameter asteroid is thought to be responsible for the mass extinction, but volcanism may also play a part.
• The Chicxulub crater is 200 km wide.
• Other evidence for the impact includes a layer of the rare metal, Iridium, derived from vapourised material, that covers the entire globe.

Conditions

• The climate is warm.
• High sea levels create numerous shallow inland seas.

Timeline

201.3 – 145.0 million years ago 

(56.3 million years)

Where have you reached on the trail?