Palaeocene

Beginning and end: major events

The start of the Palaeocene is marked by a global mass extinction at the Cretaceous–Palaeogene boundary, triggered by a combination of causes that include a large bolide impact at the Chicxulub structure and extensive volcanism associated with the Deccan Traps in what is now India. The epoch concludes with the Paleocene–Eocene Thermal Maximum (PETM), a brief but intense episode of rapid warming accompanied by major changes in ocean chemistry and life, including oxygen-depleted conditions in deeper waters.

Stratigraphy and environmental change

Formally, the Palaeocene is divided into three stages—Danian, Selandian and Thanetian—used by geologists to correlate rocks and fossils worldwide. Climatic trends during the epoch generally show a warming trajectory that culminates at the PETM. That event produced a transient global temperature spike and a pronounced perturbation in the carbon cycle, causing reduced levels of oxygen at depth and a substantial loss among deep-sea organisms such as benthic foraminifera.

Life and ecosystems

After the end-Cretaceous extinction many ecological niches were vacant, allowing surviving and newly evolving groups to diversify. On land, archaic mammals expanded rapidly: early primates, ungulate-like herbivores, small carnivorous lineages and diverse insectivores appear in the fossil record. Forests became widespread and angiosperm-dominated plant communities recovered and spread into higher latitudes, supporting complex terrestrial food webs.

Key developments and significance

• Rapid mammalian radiation that laid foundations for later modern orders.
• Recovery and reorganization of marine ecosystems, with many modern fish groups becoming common.
• Major climatic and carbon-cycle events that provide study opportunities for understanding rapid global warming and its biological consequences.

The Palaeocene is therefore important for understanding how life rebounded from a mass extinction and how early Cenozoic climates and ecosystems evolved into the patterns familiar in later epochs. For introductory and technical overviews, see summaries of the geological epoch concept and regional stratigraphic treatments that place Palaeocene rocks and fossils into global context.