The Jurassic Period
201.4–145 million years ago · 56 million years long
Giants, and the first birds
The short version
With their competitors gone, dinosaurs took over. The Jurassic is the age of the enormous long-necked sauropods and the plated and spiked plant-eaters that lived alongside them. Pangaea started splitting apart, the climate turned warm and wet, and the first birds appeared near the end.
The world then
Pangaea rifted into a northern Laurasia and a southern Gondwana, and shallow seas flooded across continental interiors as sea level rose.
Climate was warm and humid with no polar ice; conifer, cycad, ginkgo and tree-fern forests grew at high latitudes.
Life in the Jurassic
Sauropods reached extraordinary sizes — Brachiosaurus, Diplodocus, Apatosaurus — supported by air-filled vertebrae and a crop-and-swallow feeding strategy.
Large theropods such as Allosaurus and Ceratosaurus hunted them; Stegosaurus and early ankylosaurs carried plates and armour. Archaeopteryx, from the German Solnhofen limestone at about 150 Ma, is the classic early bird.
Inside the Jurassic
- Early JurassicDinosaurs radiate into empty niches.201.4–174.7 Ma
- Middle JurassicSauropods and early tyrannosauroids diversify.174.7–161.5 Ma
- Late JurassicPeak sauropod gigantism; Archaeopteryx.161.5–145 Ma
Best-documented Jurassic dinosaurs
Genera whose entire known fossil range sits inside the Jurassic, ranked by how many sites they turn up at.