For tens of millions of years what the giants were not inhabited the Earth’s oceans: 2200-pound turtle, the sea cow the size of a whale shark the size of a bus. But about 2.6 million years ago, they all started to die EN masse. Today this period is described as the extinction of marine megafauna of the Pliocene. Then for a short period became extinct more than a third of the living creatures of incredible size, including the Megalodon — a shark up to a length of 25 meters. Scientists still can not understand what was the cause of the incident.
According to researchers, is definitely one of the main factors was the climate change. Started a new ice age. Ice replaced the warm water, thus reducing food supplies for large animals. However, climate change may not be the only cause of the incident.
Preprint of an article stored on the website arxiv.org and to be published in the first issue of the journal Astrobiology for 2019, the opinion that another key factor that contributed to the mass extinction of marine giants were exploding stars.
A group of scientists, led by Adrian Melotto, Professor of physics and astronomy of the University of Kansas argues that the period of the beginning of the mass death of marine life on Earth coincides with the period of the appearance of a supernova, or maybe even a chain of small supernova nearby. And if those explosions were really strong enough, then they would flood with radiation the Ground and cause an increasing number of mutations and cancers fauna on our planet. Moreover, the process lasted several hundred years. And the larger was an animal, researchers say the worse he had under the influence of the amount of radiation.
“We calculated that the probability of cancer in a living organism the size of a man could increase to around 50 percent. And more than you, so for you it would be worse. For the same elephant or whale, the radiation dose would be even higher,” writes Melott.
The basis of the assumptions Melott and his colleagues on the survey of 2016, in which were found traces of the isotope iron-60 is a radioactive variant of the iron with a half-life of approximately 2.6 million years – in the ancient sediments of the seabed. If these radioactive isotopes were formed along with the Earth, “they would have been long gone,” says Melott. Thus, the only explanation for their presence on the planet is “bombing from the outside” a few million years ago.
Scientists, who published their study in 2016, connects discovered isotopes with a series of supernova explosions that have occurred between 8.7 and 1.7 million years ago, about 325 light years from Earth. According to Melott, a supernova erupted far enough to cause significant damage to our planet, but close enough to the Ground so she could be in the way of their residual radiation.
During stellar explosions of emitted radiation could take the form of muons, which have a similar structure with electrons. However, the difference between them is huge. Muons in two hundred times more massive than electrons and can penetrate deep enough in the Ground for hundreds of kilometers, and, of course, in the depths of the oceans. Hence the theory that after the explosion of a star, and after hitting such a stream of muons on the planet, the marine life would inadvertently come into contact with these radioactive particles, causing mutations and death of animals.
Cosmic radiation, in combination with other known factors such as climate change could become one of the causes of change, which in the end dragged the marine gigantov to the bottom. Malott notes that evidence of a supernova (or supernovae) near the Earth at that time is just “one of the pieces of the puzzle” that will help solve the mystery of the extinction of the sea monsters of the Earth. Perhaps we will never know what killed the Megalodon, but until scientists are looking into the depths of the sea, it is also worthwhile to look at the stars and planets.
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