DEFINITION OF MESOZOIC

The fourth of five main geological eras, falling

between the Paleozoic and Cenozoic, and the erathem of

rocks deposited in this era. It includes the Triassic, Jurassic,

and Cretaceous Periods. The era begins at 248 million years

ago at the end of the Permian-Triassic extinction event and

continues to 66.4 million years ago at the Cretaceous-Tertiary

(K-T) extinction event. Named by Charles Lyell in 1830,

the term means middle life, recognizing the major differences

in the fossil record between the preceding Paleozoic era, and

the succeeding Cenozoic era. Mesozoic life saw the development

of reptiles and dinosaurs, mammals, birds, many invertebrate

species that are still flourishing, and saw flowering

plants and conifers inhabit the land. The era is commonly

referred to as the age of reptiles, since they dominated the terrestrial,

marine, and aerial environments.

Pangea continued to grow in the Early Mesozoic, with

numerous collisions in eastern Asia, but as the supercontinent

grew in some areas, it was breaking apart in others. As the

fragments drifted apart especially in the later part of the Mesozoic,

continental fragments became isolated and life-forms

began to evolve separately in different places, allowing independent

forms to develop, such as the marsupials of Australia.

The Atlantic Ocean began opening as arcs and oceanic terranes

collided with western North America. In the later part of

the Mesozoic in the Cretaceous, sea levels were high and shallow

seas covered much of western North America and central

Eurasia, depositing extensive shallow marine carbonates.

Many marine organisms such as plankton rapidly diversified

and bloomed, and thick organic rich deposits formed source

rocks for numerous coal and oil fields. With the high Cretaceous

sea levels, Cretaceous rocks are abundant on many continents

and are the most represented of the Mesozoic strata.

These strata are rich in fossils that show both ancient and

modern features, including dinosaurs, ammonoids, plus newly

developed bony fishes, and flowering plants. The dinosaurs

and reptiles continued to rule the land, sea, and air until the

devastating series of events, culminating with the collision of

an asteroid or comet with Earth at the end of the Cretaceous,

eliminating the dinosaurs, and causing the extinction of 45

percent of marine genera including the ammonites, belemnites,

inoceramid clams, and large marine reptiles.

See also CRETACEOUS; JURASSIC; MASS EXTINCTIONS;

TRIASSIC.

Title Post:
Rating: 100% based on 99998 ratings. 99 user reviews.
Author:

Terimakasih sudah berkunjung di blog SELAPUTS, Jika ada kritik dan saran silahkan tinggalkan komentar