Cretaceous Period
145 – 66 million years ago · Mesozoic Era
The Cretaceous is the longest period of the Phanerozoic. It saw the greatest diversity of dinosaurs, the rise of flowering plants, and one of the most famous endings in Earth history.
At a glance
- Began
- 145 Ma
- Ended
- 66 Ma
- Duration
- 79 million years
- Era
- Mesozoic
- Climate state
- Greenhouse (warm, little or no polar ice)
- Land above sea level (PaleoDEM)
- ~32.5%
- Dinosaurs on our map
- 9
The world in the Cretaceous
Open the interactive map at 90 Ma → Elevation view Show dinosaurs on the map
What Earth was like
The continents moved toward their modern shapes. South America separated from Africa, opening the South Atlantic, and India broke away from Gondwana and raced north. Sea levels were exceptionally high: the Western Interior Seaway split North America in two, and shallow seas covered much of Europe and North Africa.
Climate
A hot greenhouse world. Carbon dioxide was several times today’s level, the poles were largely ice-free, and forests grew near the poles. Chalk from tiny plankton accumulated in warm seas, giving the period its name (creta, Latin for chalk).
Life
Flowering plants spread and diversified alongside pollinating insects. Dinosaurs reached their peak: Iguanodon and Spinosaurus earlier on, then Triceratops, Ankylosaurus, Velociraptor, Parasaurolophus and Tyrannosaurus rex. Mosasaurs ruled the seas and pterosaurs such as Quetzalcoatlus soared overhead.
Dinosaurs of the Cretaceous
These genera from our map lived during the Cretaceous. Bars show each genus’s accepted time range within the period.
- Iguanodon
- Spinosaurus
- Parasaurolophus
- Velociraptor
- Edmontosaurus
- Pachycephalosaurus
- Tyrannosaurus rex
- Ankylosaurus
- Triceratops
Silhouettes via PhyloPic: Iguanodon — Tasman Dixon, CC0 1.0 (PhyloPic) · Spinosaurus — Alessio Ciaffi, CC BY 4.0 (PhyloPic) · Parasaurolophus — Richard Rich, CC0 1.0 (PhyloPic) · Velociraptor — Itai Fein, CC0 1.0 (PhyloPic) · Edmontosaurus — Ivan Iofrida, CC BY 4.0 (PhyloPic) · Pachycephalosaurus — Emily Willoughby, CC BY-SA 3.0 (PhyloPic) · Tyrannosaurus — Fred Wierum, CC BY 4.0 (PhyloPic) · Ankylosaurus — Itai Fein, CC0 1.0 (PhyloPic) · Triceratops — Jagged Fang Designs, CC0 1.0 (PhyloPic)
How it ended
At 66 million years ago an asteroid about 10 km wide struck Chicxulub, Mexico, while the Deccan Traps erupted in India. Around three quarters of species, including all non-avian dinosaurs, went extinct.
Key facts
- The Cretaceous lasted about 79 million years.
- T. rex lived only in the last few million years of the period.
- Flowering plants now make up about 90% of land plant species.
Data: land and sea
Across the Cretaceous, an average of 32.5% of Earth’s surface stood above reconstructed sea level (range 27.5–36.8%). Today the same model gives 31.8%.
Where this data comes from
- Continent positions: GPlates Web Service, Müller et al. (2019) plate model, covering 0–250 Ma.
- Elevation and shorelines: PALEOMAP PaleoDEMs, Scotese & Wright (2018), doi:10.5281/zenodo.5460860, CC BY 4.0.
- Dinosaur fossils: Paleobiology Database occurrence records.
- Period boundaries: ICS International Chronostratigraphic Chart (2023/09).
These are scientific reconstructions, not observations. Uncertainty grows the further back in time you go. About & data sources
Related reading
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- About & data sourcesWhere the reconstructions and fossil data come from.