Kreidezeit

Kreidezeit, literally “chalk era,” is the German term for the Cretaceous period, the last division of the Mesozoic Era. It lasted about 79 million years, spanning roughly from 145 million to 66 million years ago, and followed the Jurassic while preceding the Paleogene.

Geology and climate during the Kreidezeit were characterized by a generally warm global climate and high sea levels. Large portions of continents were submerged by shallow seas, creating expansive epicontinental waters. The ongoing break-up of the supercontinent Pangaea contributed to widespread tectonic activity and changing coastlines. The period is well known for extensive chalk deposits, especially in Europe, formed by calcareous nannoplankton and coccolithophores that accumulated on the seafloor.

Biologically, the Kreidezeit saw continued dominance and diversification of dinosaurs, including large sauropods and theropods, as well as the early evolution of birds. Angiosperms (flowering plants) diversified, adding a new dimension to terrestrial ecosystems alongside conifers and ferns. In the oceans, ammonites, belemnites, mosasaurs, and plesiosaurs were common, while planktonic organisms contributed to the formation of major chalk beds.

The end of the Kreidezeit was marked by a major biotic crisis about 66 million years ago, commonly attributed to an asteroid impact at the Chicxulub crater, together with large-scale volcanic activity (such as the Deccan Traps). This Paleogene boundary event led to the mass extinction of most non-avian dinosaurs and many marine groups, paving the way for mammalian and other faunal radiations.

In German geology and paleontology, Kreidezeit remains a standard term for this interval, with subdivisions typically recognized as Early and Late Kreidezeit (approximately 145–100 Ma and 100–66 Ma, respectively).