Huge carnivores like Tyrannosaurus rex and Giganotosaurus appeared, as did Triceratops and many, many others. There was a tremendous diversity in dinosaur species. Mammals were flourishing, and flowering plants developed and radically changed the landscape.
Flora[ edit ] Although the first representatives of leafy trees and true grasses emerged in the Cretaceous, the flora was still dominated by conifers like Araucaria Here: Modern Araucaria araucana in Chile.
Flowering plants angiosperms spread during this period, although they did not become predominant until the Campanian Age near the end of the period. Their evolution was aided by the appearance of bees ; in fact angiosperms and insects are a good example of coevolution.
The first representatives of many leafy trees, including figsplanes and magnoliasappeared in the Cretaceous. Some fern orders such as Gleicheniales appeared as early in the fossil record as the Cretaceous and achieved an early broad distribution.
Various "archaic" groups like eutriconodonts were common The cretaceous period the Early Cretaceous, but by the Late Cretaceous northern mammalian faunas were dominated by multituberculates and therianswith dryolestoids dominating South America.
The apex predators were archosaurian reptilesespecially dinosaurswhich were at their most diverse stage. Pterosaurs were common in the early and middle Cretaceous, but as the Cretaceous proceeded they declined for poorly understood reasons once thought to be due to competition with early birdsbut now it is understood avian adaptive radiation is not consistent with pterosaur decline and by the end of the period only two highly specialized families remained.
The coelurosaur dinosaurs found there represent types of the group Maniraptorawhich is transitional between dinosaurs and birds, and are notable for the presence of hair-like feathers.
Insects diversified during the Cretaceous, and the oldest known antstermites and some lepidopteransakin to butterflies and mothsappeared. Aphidsgrasshoppers and gall wasps appeared. Up to 2 m long and 0. Triceratopsone of the most recognizable genera of the Cretaceous Confuciusornisa genus of crow-sized birds from the Early Cretaceous Ichthyornis was a toothed seabird -like ornithuran from the late Cretaceous period Marine fauna[ edit ] In the seas, raysmodern sharks and teleosts became common.
Baculitesan ammonite genus with a straight shell, flourished in the seas along with reef-building rudist clams. The Hesperornithiformes were flightless, marine diving birds that swam like grebes.
Globotruncanid Foraminifera and echinoderms such as sea urchins and starfish sea stars thrived. The first radiation of the diatoms generally siliceous shelled, rather than calcareous in the oceans occurred during the Cretaceous; freshwater diatoms did not appear until the Miocene.
A scene from the early Cretaceous: Tylosaurus was a large mosasaurcarnivorous marine reptiles that emerged in the late Cretaceous.
Strong-swimming and toothed predatory waterbird Hesperornis roamed late Cretacean oceans. Cretaceous—Paleogene extinction event The impact of a large body with the Earth may have been the punctuation mark at the end of a progressive decline in biodiversity during the Maastrichtian Age of the Cretaceous Period.
The impact created the sharp break known as K—Pg boundary formerly known as the K—T boundary.The Cretaceous Period ended with a mass extinction event in which about 75 percent of all species, including marine, freshwater, and terrestrial organisms, became extinct.
See Chart at geologic time.
The Cretaceous (/ k r ɪ ˈ t eɪ ʃ ə s /, kri-TAY-shəs) is a geologic period and system that spans 79 million years from the end of the Jurassic Period million years ago to the beginning of the Paleogene Period 66 mya.
It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon. The Cretaceous period was the heyday of the dinosaurs. Huge carnivores like Tyrannosaurus rex and Giganotosaurus appeared, as did Triceratops and many, many others.
There was a tremendous diversity in dinosaur species. The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction, was a sudden mass extinction of some three-quarters of the plant and animal species on Earth, approximately 66 million years ago. The Cretaceous Period.
The Cretaceous is usually noted for being the last portion of the "Age of Dinosaurs", but that does not mean that new kinds of dinosaurs did not appear then.
It is during the Cretaceous that the first ceratopsian and pachycepalosaurid dinosaurs appeared. Also during this time, we find the first fossils of many insect .
The Cretaceous as a separate period was first defined by Belgian geologist Jean d’Omalius d’Halloy in , using strata in the Paris Basin and named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates, principally coccoliths), found in the upper Cretaceous of western Europe.