The Dinosaurs Of The Mesozoic Era Belonged To Which Animal Group?

Mesozoic era: Age of the dinosaurs

New inquiry suggests that reptiles that lived during the dinosaur age were difficult-hit. Here, the cannibal cadger Palaeosaniwa chases a pair of immature Edmontosaurus while the snake Cerberophis and the lizard Obamadon look on. (Image credit: Carl Buell)

During the Mesozoic, or "Middle Life" era, life diversified apace and giant reptiles, dinosaurs and other monstrous beasts roamed the World. The period, which spans from about 252 million years agone to about 66 million years ago, was besides known as the age of reptiles or the age of dinosaurs.

Boundaries

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

The Permian-Triassic boundary, at the start of the Mesozoic, is divers relative to a particular department of sediment in Meishan, China, where a type of extinct, eel-like creature known every bit a conodont first appeared, according to the International Commission on Stratigraphy.

The end boundary for the Mesozoic era, the Cretaceous-Paleogene purlieus, is defined by a xx-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 affect that wiped out the dinosaurs. The Mesozoic era is divided up 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 pct of all terrestrial species on the planet. Life slowly rebounded, eventually giving way to a flourishing diverseness of animals, from massive lizards to monstrous dinosaurs.

The Triassic period, from 252 one thousand thousand to 200 million years ago, saw the rising of reptiles and the first dinosaurs. The Jurassic period, from about 200 meg to 145 1000000 years ago, ushered in birds and mammals. And the Cretaceous period, from 145 one thousand thousand to 66 meg years ago is known for its iconic dinosaurs, such asTriceratops , and pterosaurs such equallyPteranodon.

Coniferous plants, or those that accept cone-bearing seeds, already existed at the start of the era, but they became much more than abundant during the Mesozoic. Flowering plants emerged during the late Cretaceous period. The lush found life during the Mesozoic era provided plenty of food, allowing the biggest of the dinosaurs, such equally theArgentinosaurus, to grow up to 80 tons, according to a 2005 report in the journal 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 nevertheless formed one massive supercontinent. Without much coastline to moderate the continent'south interior temperature, Pangaea experienced major temperature swings and was covered in large swaths of desert. Notwithstanding the region still had a belt of tropical rainforest in regions around the equator, said Brendan Spud, an earth scientist at St. Francis Xavier University in Antigonish, Canada.

Extinctions

The Mesozoic era was bookended by two cracking extinctions, with another smaller extinction occurring at the end of the Triassic menstruum, Olsen said.

Around 252 one thousand thousand years ago, the end-Permian extinction wiped out near life on Earth over about 60,000 years, co-ordinate to a February 2014 study in the journal Proceedings of the National University of Sciences (PNAS). At the end of the Triassic period, roughly 201 1000000 years ago, near amphibious creatures and crocodile-similar creatures that lived in the tropics were wiped out. About 65 million years ago, a giant asteroid blasted into Earth and formed a behemothic crater at Chicxulub in the Yucatan Peninsula.

Because the fossil record is incomplete, it'southward difficult to say exactly what acquired the extinctions, or even how chop-chop they occurred. Later all, certain species or traces of catastrophic events could be missing in the fossil tape 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 Alive Science.

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

At the end of the Permian, the Siberian Traps underwent massive volcanic eruptions, which nigh geologists believe caused the world'southward biggest extinction. Exactly how, yet, is up for debate.

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 take increased bounding main surface temperatures and led to ocean acidification that choked 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 past nickel-munching microbes known asMethanosarcina. Those microbes may have belched out huge amounts of marsh gas, superheating the planet.

Nigh scientists agree that an asteroid bear on wiped out the dinosaurs at the cease of the Cretaceous menses. The impact would have kicked up so much dust that it blocked the lord's day, halted photosynthesis, and led to such a huge disruption in the food concatenation that everything that wasn't a scavenger or very small died.

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

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

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

"When you have these volcanic winters, where temperatures may have dropped even below freezing in the torrid zone, it was devastating," Olsen said.

Originally published on Live Science.

Additional resource

Academy of California Museum of Paleontology: The Mesozoic Era
Howard Hughes Medical Institute: The Day the Mesozoic Died

Tia is the managing editor and was previously a senior writer for Live Science. Her piece of work has appeared in Scientific American, Wired.com and other outlets. She holds a chief's caste in bioengineering from the Academy of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor'due south degree in mechanical technology from the University of Texas at Austin. Tia was part of a squad at the Milwaukee Journal 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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