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The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was largely ice-free, although there is some evidence ...
The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at 66 million years, [2] with radiometric dating yielding a more precise age of 66.043 ± 0.043 Ma. [3]
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after creta, the Latin word for the white limestone known as chalk.
The Cretaceous is the Phanerozoic's longest period and the last period of the Mesozoic. It spans from 145 million to 66 million years ago, and is divided into two epochs: Early Cretaceous, and Late Cretaceous. [53] Tylosaurus, a type of large marine lizards known as mosasaurs
That was life - and death - in the Cretaceous Period in the Canadian province of Alberta. About 76 million years ago, a juvenile of one of the largest flying creatures in Earth's history, called ...
The Cretaceous is justly famous for its chalk; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic. [51] Mid-ocean ridge activity—or rather, the circulation of seawater through the enlarged ridges—enriched the oceans in calcium; this made the oceans more saturated, as well as increased the bioavailability ...
During the Cretaceous, the dominant group of living fishes, the teleosts, first achieved ascendency over their holostean forebears. [81] The aquatic toothed bird Hesperornis is the only known Cretaceous bird whose remains are found with any frequency in North America. [82] Near the end of the Cretaceous, the Western Interior Seaway began to ...
The Early Cretaceous (geochronological name) or the Lower Cretaceous (chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 Ma to 100.5 Ma.