19 Facts About Cretaceous


Cretaceous is a geological period that lasted from about 145 to 66 million years ago.

FactSnippet No. 1,578,542

Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas.

FactSnippet No. 1,578,543

Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out.

FactSnippet No. 1,578,544

The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.

FactSnippet No. 1,578,545

In older literature, the Cretaceous is sometimes divided into three series: Neocomian, Gallic and Senonian.

FactSnippet No. 1,578,546

Lower boundary of the Cretaceous is currently undefined, and the Jurassic–Cretaceous boundary is currently the only system boundary to lack a defined Global Boundary Stratotype Section and Point.

FactSnippet No. 1,578,547

Calpionellids, an enigmatic group of planktonic protists with urn-shaped calcitic tests briefly abundant during the latest Jurassic to earliest Cretaceous, have been suggested as the most promising candidates for fixing the Jurassic–Cretaceous boundary.

FactSnippet No. 1,578,548

Upper boundary of the Cretaceous is sharply defined, being placed at an iridium-rich layer found worldwide that is believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatan Peninsula and extending into the Gulf of Mexico.

FactSnippet No. 1,578,549

High sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms.

FactSnippet No. 1,578,550

The Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type that is formed under warm, shallow marine conditions.

FactSnippet No. 1,578,551

Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed.

FactSnippet No. 1,578,552

In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast.

FactSnippet No. 1,578,553

In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls.

FactSnippet No. 1,578,554

Cretaceous is justly famous for its chalk; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic.

FactSnippet No. 1,578,555

Flowering plants underwent a rapid radiation beginning during the middle Cretaceous, becoming the dominant group of land plants by the end of the period, coincident with the decline of previously dominant groups such as conifers.

FactSnippet No. 1,578,556

Rhynchocephalians disappeared from North America and Europe after the Early Cretaceous, and were absent from North Africa and northern South America by the early Late Cretaceous.

FactSnippet No. 1,578,557

Choristoderes, a group of freshwater aquatic reptiles that first appeared during the preceding Jurassic, underwent a major evolutionary radiation in Asia during the Early Cretaceous, which represents the high point of choristoderan diversity, including long necked forms such as Hyphalosaurus and the first records of the gharial-like Neochoristodera, which appear to have evolved in the regional absence of aquatic neosuchian crocodyliformes.

FactSnippet No. 1,578,558

The Cretaceous was an important interval in the evolution of bioerosion, the production of borings and scrapings in rocks, hardgrounds and shells.

FactSnippet No. 1,578,559

Cretoxyrhina, one of the largest Cretaceous sharks, attacking a Pteranodon in the Western Interior Seaway.

FactSnippet No. 1,578,560