Mammals and birds radiated rapidly after the extinction. The India–Eurasia collision raised the Himalayas and the Antarctic ice sheet formed as Earth began cooling.
Explore the Paleogene Earth in 3D →The Chicxulub impact 66 million years ago spread dust, sulfur and soot into the atmosphere, darkening and cooling Earth and disrupting food webs. Non-avian dinosaurs disappeared; a 2024 isotope study supports a carbonaceous asteroid that formed beyond Jupiter’s orbit.
Around 66 million years ago, enormous Deccan eruptions built thick lava sequences in present-day India. Carbon dioxide could drive prolonged warming and sulfur brief cooling, but volcanism’s contribution to extinction alongside Chicxulub remains debated.
About 56 million years ago, a large carbon release raised global temperatures by roughly 5–8°C and acidified the oceans. The full warming-and-recovery episode lasted around 200,000 years. The carbon sources and release rate remain under study, so comparisons with modern warming must account for different timescales.
By around 50 million years ago, India–Asia collision was underway as remaining Tethyan seas closed. Initial contact may have occurred earlier in different regions; today’s Himalaya reflects tens of millions of years of subsequent crustal shortening and uplift.
Fossils from roughly 52–40 million years ago trace the transition from land-dwelling whale relatives to aquatic forms. By around 40 million years ago, some whales lived entirely in the sea, while other branches still had weight-bearing hind limbs.
Around 49 million years ago, Arctic sediments recorded abundant Azolla, a floating freshwater fern, over an interval of about 800,000 years. Some may have grown on fresh surface waters, while other remains washed in from land. Its carbon burial may have aided cooling, but its geographic extent and global climate effect remain uncertain.
Around 36 million years ago, the Popigai impact left a roughly 100-kilometre crater in northern Siberia. Shock transformed graphite in the rocks into tiny diamonds, mostly polycrystalline grains better suited to industrial uses than gemstones.
Around 34 million years ago, global cooling accompanied major Antarctic ice-sheet growth. Falling carbon dioxide is a leading driver; ocean gateways and orbital variations also mattered, but a single current cannot explain the transition.
By about 25–20 million years ago, grass-rich habitats were expanding in several regions, with different regional histories. Many modern tropical C4 grasslands spread much later, especially around 8–3 million years ago. Climate, fire and grazing interacted, while herbivore adaptations did not always appear at the same time as open grasslands.