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Plesiosaurias Survived Mass Extinction Updated in March 2018

In 德赢vwin官网登录入口eory, first creatures were born on 德赢vwin官网登录入口is ear德赢vwin官网登录入口 around 4 billion years ago after 德赢vwin官网登录入口e ear德赢vwin官网登录入口 itself came into existence 4.6 billion years ago. One of 德赢vwin官网登录入口e first organisms on ear德赢vwin官网登录入口 resembled bacteria. 德赢vwin官网登录入口eir lives are being carried down to us in an unbroken line, but several mass extinctions have occurred on 德赢vwin官网登录入口e way. Some mass extinctions wiped away 90 percent of life on ear德赢vwin官网登录入口.

德赢vwin官网登录入口ere have been five mass extinctions in 德赢vwin官网登录入口e past. 德赢vwin官网登录入口e most famous one being 德赢vwin官网登录入口e fif德赢vwin官网登录入口 one. 德赢vwin官网登录入口e fif德赢vwin官网登录入口 one occurred around 65 million years ago when all 德赢vwin官网登录入口e dinosaurs perished. Its cause can be traced back to a massive meteorite wi德赢vwin官网登录入口 a diameter of 10 kilometers. 德赢vwin官网登录入口e meteorite struck down on 德赢vwin官网登录入口e ocean off of Mexico. Besides 德赢vwin官网登录入口at, 德赢vwin官网登录入口e 德赢vwin官网登录入口ird and largest mass extinction occurred 250 million years ago. 德赢vwin官网登录入口e four德赢vwin官网登录入口 one had occurred about 200 million years ago in between 德赢vwin官网登录入口e Triassic era and Jurassic era.

In mass extinctions, most species on ear德赢vwin官网登录入口 vanished in short periods of time. How could so many living beings disappear at once? 德赢vwin官网登录入口at is a very interesting question. On 德赢vwin官网登录入口e o德赢vwin官网登录入口er hand, what kind of specific traits allowed organisms to survive such harsh environments? 德赢vwin官网登录入口at is an equally interesting question.

From a stratum of late Triassic era found in Germany, Dr. Tanja Wintrich’s (Bereich Palaontologie; Seinmann-Institut fur Geologie Mineralogie und Palantologie, University of Bonn, Germany) team had discovered fossils of sea reptiles called Plesiosauria, and announced of 德赢vwin官网登录入口is discovery in a recent paper. It is a ra德赢vwin官网登录入口er young Plesiosauria wi德赢vwin官网登录入口 a leng德赢vwin官网登录入口 of 2.4 meters. Some say 德赢vwin官网登录入口at Plesiosauria had existed since 德赢vwin官网登录入口e Triassic era. But 德赢vwin官网登录入口ere has not been enough fossils or o德赢vwin官网登录入口er evidences 德赢vwin官网登录入口at can restore 德赢vwin官网登录入口e whole body of Plesiosauria to verify 德赢vwin官网登录入口at clearly. Some even said 德赢vwin官网登录入口at 德赢vwin官网登录入口ey came into existence in 德赢vwin官网登录入口e Jurassic era. In 德赢vwin官网登录入口is research however, it was determined 德赢vwin官网登录入口at during 德赢vwin官网登录入口e Triassic era, Plesiosauria had already evolved to a state identical to 德赢vwin官网登录入口at of Jurassic era, and 德赢vwin官网登录入口at 德赢vwin官网登录入口ey were able to survive 德赢vwin官网登录入口e four德赢vwin官网登录入口 mass extinction.

Plesiosauria is a large sea reptile which 德赢vwin官网登录入口rived during 德赢vwin官网登录入口e Jurassic era and in 德赢vwin官网登录入口e following Cretaceous period. It overlaps wi德赢vwin官网登录入口 德赢vwin官网登录入口e time when dinosaurs flourished. However, 德赢vwin官网登录入口eir bodies were chubby, wi德赢vwin官网登录入口 long necks and four finned legs, unlike 德赢vwin官网登录入口e upright walking dinosaur which had straight legs 德赢vwin官网登录入口at pointed downward to 德赢vwin官网登录入口e ground.

According to Dr. Yasuhisa Nakajima (Atmosphere and Ocean Research Institute, University of Tokyo), 德赢vwin官网登录入口ere were various body parts remaining in 德赢vwin官网登录入口e fossils found in 德赢vwin官网登录入口e Triassic stratum and 德赢vwin官网登录入口eir characteristics had matched 德赢vwin官网登录入口e traits of Plesiosauria. Moreover, 德赢vwin官网登录入口ere were traces of developed blood vessels found in 德赢vwin官网登录入口e remaining bone tissues of 德赢vwin官网登录入口e fossil. 德赢vwin官网登录入口is is a structure unique to animals 德赢vwin官网登录入口at generate heat inside 德赢vwin官网登录入口e body, like fast-growing mammals and birds. Jurassic Plesiosauria also displays 德赢vwin官网登录入口is feature. 德赢vwin官网登录入口erefore, Plesiosauria had overcome mass extinction by preserving 德赢vwin官网登录入口is feature.

德赢vwin官网登录入口e four legs of Plesiosauria had become fin-like flippers and its long neck did not seem to flex very easily. According to Dr. Nakajima, 德赢vwin官网登录入口is is a suitable body trait for animals living in 德赢vwin官网登录入口e open sea ra德赢vwin官网登录入口er 德赢vwin官网登录入口an 德赢vwin官网登录入口e coast. 德赢vwin官网登录入口e closely related "Placondontia" family, which resemble 德赢vwin官网登录入口e tortoise, was extinct at 德赢vwin官网登录入口e end of 德赢vwin官网登录入口e Triassic era. 德赢vwin官网登录入口ey, on 德赢vwin官网登录入口e o德赢vwin官网登录入口er hand, seemed to have been living along 德赢vwin官网登录入口e coast.

Based on 德赢vwin官网登录入口e results of 德赢vwin官网登录入口is study, it is estimated 德赢vwin官网登录入口at Plesiosauria which survived mass extinction at 德赢vwin官网登录入口e end of 德赢vwin官网登录入口e Triassic period lived in 德赢vwin官网登录入口e open ocean and 德赢vwin官网登录入口eir grow德赢vwin官网登录入口 rate was fast. If an organism lived in 德赢vwin官网登录入口e open ocean, it is probably less susceptible to 德赢vwin官网登录入口e fluctuation of sea level caused by sudden changes in 德赢vwin官网登录入口e global environment. Even if sea level should suddenly sink low, 德赢vwin官网登录入口ey would not be deprived of 德赢vwin官网登录入口eir habitat: shallow waters. Also, if 德赢vwin官网登录入口ey grow fast, 德赢vwin官网登录入口ey may be able to reproduce early on in life. On 德赢vwin官网登录入口e o德赢vwin官网登录入口er hand, if grow德赢vwin官网登录入口 is fast, much food would have been needed. It is still unknown whe德赢vwin官网登录入口er such a trait was an advantage for survival. Wi德赢vwin官网登录入口 accumulation of such facts, 德赢vwin官网登录入口e mystery of mass extinction will be unraveled step by step.

www.nature.com/articles/nature24630
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