lateCretaceous

The late Cretaceous, sometimes written lateCretaceous, is the final epoch of the Cretaceous Period, spanning roughly 100.5 to 66 million years ago. It comprises the Campanian and Maastrichtian ages, a time of generally high global temperatures, high sea levels, and widespread shallow seas. Continental configurations were still shifting after the breakup of Pangaea, with major seaways such as a large Western Interior Seaway in North America shaping marine and coastal environments.

During this interval, ecosystems were diverse and dynamic. Angiosperms (flowering plants) diversified and became globally important, alongside conifers and ferns. Dinosaurs remained ecologically dominant on land, including large herbivores such as hadrosaurs, ceratopsians, and titanosaurs, as well as various predators. Marine life included mosasaurs, plesiosaurs, and a variety of invertebrates, while birds and small mammals continued to diversify, setting the stage for mammalian dominance after the extinction event at the end of the period.

Towards its end, the late Cretaceous saw significant geological and climatic developments. The Deccan Traps in what is now India produced extensive volcanic activity, contributing to atmospheric changes and climatic stress. A large asteroid impact near the present-day Yucatán Peninsula (Chicxulub crater) caused a global catastrophe about 66 million years ago, triggering a mass extinction that eliminated non-avian dinosaurs, most marine reptiles, and many other organisms, while birds, certain mammals, and several plant and invertebrate groups survived and later radiated.

The end-Cretaceous extinction opened ecological niches that propelled rapid diversification in the early Cenozoic, particularly among mammals and birds.