What Major Group Of Animals Dominated The Mesozoic Era

Mesozoic era: Age of the dinosaurs

New research suggests that reptiles that lived during the dinosaur age were hard-hitting. Here, the carnivorous cadger Palaeosaniwa chases a pair of immature Edmontosaurus while the snake Cerberophis and the lizard Obamadon await on. (Image credit: Carl Buell)

During the Mesozoic, or "Eye Life" era, life diversified rapidly and giant reptiles, dinosaurs and other monstrous beasts roamed the World. The period, which spans from nigh 252 one thousand thousand years ago to about 66 one thousand thousand years ago, was as well known equally the age of reptiles or the age of dinosaurs.

Boundaries

English geologist John Phillips, the beginning person to create the global geologic timescale, first coined the term Mesozoic in the 1800s. Phillips establish ways to correlate sediments found effectually the world to specific time periods, said Paul Olsen, a geoscientist at the Lamont-Doherty Globe Observatory at Columbia University in New York.

The Permian-Triassic purlieus, at the kickoff of the Mesozoic, is divers relative to a particular section of sediment in Meishan, China, where a blazon of extinct, eel-similar creature known as a conodont start appeared, according to the International Commission on Stratigraphy.

The end boundary for the Mesozoic era, the Cretaceous-Paleogene boundary, is defined by a twenty-inch (50 centimeters) thick sliver of rock in El Kef, Tunisia, which contains well-preserved fossils and traces of iridium and other elements from the asteroid impact that wiped out the dinosaurs. The Mesozoic era is divided upwardly into the Triassic, Jurassic, and Cretaceous periods.

Life and climate

The Mesozoic era began roughly around the time of the end-Permian extinction, which wiped out 96 percentage of marine life and 70 per centum of all terrestrial species on the planet. Life slowly rebounded, eventually giving way to a flourishing diversity of animals, from massive lizards to monstrous dinosaurs.

The Triassic catamenia, from 252 meg to 200 one thousand thousand years ago, saw the rise of reptiles and the start dinosaurs. The Jurassic menstruum, from near 200 million to 145 million years ago, ushered in birds and mammals. And the Cretaceous period, from 145 meg to 66 million years agone is known for its iconic dinosaurs, such asTriceratops , and pterosaurs such asPteranodon.

Coniferous plants, or those that take cone-begetting seeds, already existed at the showtime of the era, merely they became much more arable during the Mesozoic. Flowering plants emerged during the late Cretaceous menstruum. The lush plant life during the Mesozoic era provided plenty of food, assuasive the biggest of the dinosaurs, such as theArgentinosaurus, to grow up to 80 tons, according to a 2005 study in the periodical Revista del Museo Argentino de Ciencias Naturales.

Earth during the Mesozoic era was much warmer than today, and the planet had no polar ice caps. During the Triassic period, Pangaea still formed one massive supercontinent. Without much coastline to moderate the continent'due south interior temperature, Pangaea experienced major temperature swings and was covered in big swaths of desert. Yet the region still had a belt of tropical rainforest in regions around the equator, said Brendan White potato, an earth scientist at St. Francis Xavier Academy in Antigonish, Canada.

Extinctions

The Mesozoic era was bookended past two great extinctions, with some other smaller extinction occurring at the stop of the Triassic catamenia, Olsen said.

Around 252 1000000 years ago, the end-Permian extinction wiped out well-nigh life on Earth over about lx,000 years, according to a February 2014 study in the journal Proceedings of the National Academy of Sciences (PNAS). At the terminate of the Triassic period, roughly 201 1000000 years ago, most amphibious creatures and crocodile-similar creatures that lived in the torrid zone were wiped out. About 65 one thousand thousand years agone, a behemothic asteroid blasted into Earth and formed a giant crater at Chicxulub in the Yucatan Peninsula.

Considering the fossil tape is incomplete, information technology's hard to say exactly what caused the extinctions, or fifty-fifty how rapidly they occurred. After all, certain species or traces of catastrophic events could be missing in the fossil record simply because the sediments may have disappeared over tens of millions of years, Olsen said.

"Nature is very efficient at getting rid of its corpses," Olsen told Live Scientific discipline.

However, there are a few prime suspects in each of the extinctions.

At the end of the Permian, the Siberian Traps underwent massive volcanic eruptions, which most geologists believe caused the world's biggest extinction. Exactly how, however, is upwards for fence.

The volcanic eruptions caused a spike in carbon dioxide in the atmosphere, though the 2014 PNAS study suggests that the spike was brief. The eruptions may have increased sea surface temperatures and led to ocean acidification that high-strung out bounding main life. And another study published in March 2014 in PNAS proposed that the eruptions released huge troves of the element nickel, which fueled a feeding frenzy by nickel-munching microbes known asMethanosarcina. Those microbes may have belched out huge amounts of methane, superheating the planet.

Most scientists concord that an asteroid affect wiped out the dinosaurs at the end of the Cretaceous period. The affect would have kicked up so much dust that it blocked the sun, halted photosynthesis, and led to such a huge disruption in the food chain that everything that wasn't a scavenger or very small died.

But the Deccan Traps, in what is now India, were spewing massive amounts of lava both before and afterwards the asteroid impact, and a few scientists believe these flows either directly acquired or accelerated the dinosaurs' demise.

Volcanism may also exist to blame for the finish-Triassic extinction. Though volcanism in general leads to global warming, after an initial volcanic eruption, huge amounts of sulfur spew into the air and cause a cursory menstruum of global cooling. Such cooling-heating cycles may have occurred hundreds of times over 500,000 years. Similar common cold snaps have been tied to huge crop failures in historical times, such as in Iceland in the 1700s, Olsen said.

As a issue, animals used to abiding, balmy temperatures in the tropics were wiped out, while animals that were insulated with proto-feathers, such as pterosaurs, or that lived at college latitudes and were already adapted to big temperature variations, did just fine, Olsen said.

"When y'all have these volcanic winters, where temperatures may have dropped fifty-fifty below freezing in the torrid zone, it was devastating," Olsen said.

Originally published on Live Scientific discipline.

Additional resources

Academy of California Museum of Paleontology: The Mesozoic Era
Howard Hughes Medical Institute: The Twenty-four hour period the Mesozoic Died

Tia is the managing editor and was previously a senior author for Live Science. Her piece of work has appeared in Scientific American, Wired.com and other outlets. She holds a master's degree in bioengineering from the Academy of Washington, a graduate document in science writing from UC Santa Cruz and a bachelor'southward degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Periodical Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.

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