In an astounding discovery, paleontologists have discovered fossils that testify to the incredible devastation in the hours and days after the Earth hit by the impactor that created the Chicxulub Crater off the Yucatan Peninsula in Mexico, 66 million years ago the dinosaurs with it.
The end of the Cretaceous in still life
A team of paleontologists from the University of Kansas (KU) in North Dakota have found fossils that capture a snapshot of the moments immediately after most catastrophic event that life on earth ever had to endure; the impact event that produced the Chicxulub crater some 66 million years ago, suspected of leading the dinosaurs' reign to a sudden, violent end. 1
"The sedimentation was so rapid that everything is conserved in three dimensions – they are not crushed," said David Burnham, pioneer of vertebrate paleontology at KU Biodiversity Institute. "It's like an avalanche that breaks down almost like a liquid and then solidifies like concrete. They were killed quite suddenly because of the violence of this water. We have a fish that hit a tree and was broken in half. "
The Chicxulub Impactor, the Chicxulub Crater, and the Alvarez Hypothesis
Since the discovery of their fossils in the 19th century, dinosaurs have been the subject of endless fascination for scientists and the general public. The imagination plays in this megafauna scale, its diversity and especially its sudden and complete disappearance from the fossil record at the end of the Cretaceous, about 66 million years ago .
The extinction of animals such as the Tyranosaurus rex remained one of the great mysteries of science, to 1980 Nobel laureate Luis Alvarez, his son Walter Alvarez, a geologist at UC Berkeley, and chemists Frank Asaro and Helen Vaughn Michel [PDF] announced the discovery of a concentrated layer of iridium in the geological records directly on the border between the Cretaceous and Paleogene periods, often referred to as the KT boundary.
Nearly 100 times The concentration we would expect on Earth – iridium is a very rare element on Earth – and in locations around the world only the iridium layer of Alverez could be found by one thing explained. A massive impactor, either an asteroid or a comet, hit Earth 66 million years ago and had enough iridium to spread it in a thick layer around the world.
"We understand that bad things happened … but no one has found that kind of evidence." – David Burnham, United States of Kansas
Such an impactor would have to be somewhere from According to a recent study, the diameter had a diameter of 6.5 to 50.25 miles (19459017), and somewhat that would have been so great would have caused such mad ravages that entire animal species, including dinosaurs, would have died out almost overnight. It is believed that the Chicxulub Impactor released 100 million megatons of energy or just over 7 billion Hiroshima bombs . The only thing missing in Alvarez's hypothesis, as it was called, was a crater from the impact, and so it remained controversial. Even after the discovery of the Chicxulub crater off the Yucatan Peninsula in 1994.
Now that these new findings from the KU team are as close to photographic evidence as we find in the geological records, we can now use the Alvarez The hypothesis takes place as it happened.
"We understood that bad things happened right after the impact, but no one has found that kind of violence," Burnham said. "People said," We know that this explosion killed the dinosaurs, but why do not we have bodies everywhere? They are not dinosaurs, but I think they will be found someday. "
According to the KU team, the fossils at the Tanis site were all a" rapidly installed high-energy deposit. "
"A tumbled mass of freshwater fish, terrestrial animals, trees, branches, tree trunks, marine ammonites, and other marine life has been packed into this stratum by the inland direction," said Robert DePalma, a KU graduate student in geology at the University of California KU Biodiversity Institute and Natural History Museum and lead author of the upcoming work.
Impact Ejecta and an Ancient Seaway
In the minutes after the impact, the earth's crust crashed violently out of the impact like a lake after a stone was thrown in. And as well as displaced water from the surface of a stone on the surface would splash up and down, also the earth crust and the top coat after the Chicxulub Impactor hit.
This material, known as impact ejection, is one of the most important markers of an impact event in geological documentation, as impact ejections are often characterized by high-pressure and shock metamorphism that can not be produced by other natural processes on Earth.
Besides the ejection, the shocks that would be weighed by the impact would orbit the globe and produce violent tsunamis in waterways half a world away. The Tanis area and sediment deposits at the KT border were the product of one of these tsunamis.
"A tsunami would have taken at least 17 or more hours to reach the area of [Chicxulub crater]but seismic waves – and a subsequent climb – would have reached it in ten minutes," DePalma said. These seismic waves, located next to the carved bed of an ancient seaway, would have created tsunamis on that waterway and into the Tanis area before the ejection of the impact from the sky over North America had come to an end.
One species of fish The ejecta found on site had time to breathe in this ejecta, which had reached a few minutes before the tsunami in the river valley.
"The fish were quickly buried, but not so fast they did not have time to breathe the spit that rained down to the river," Burnham said. "These fish were not underpants, they breathed them while swimming in the water column. We find small pieces of chaff in the gills of these fish, the bony supports for the gills. We do not know if some were killed by inhaling this ejecta. "
DePalma believes that this site with hundreds of preserved specimens of a wide variety of species, some of which are completely new to science, fills a huge gap in the record of Chicxulub Impactor and its aftermath.
"It's hard not to repress this topic," he said. "We are taking snapshots of one of Earth's most remarkable effects. No other location has such a record. And this special event is bound to us all – to every mammal on earth. Because here we essentially inherited the planet. Nothing was the same after the impact. It became a planet of mammals and not a planet of dinosaurs.
"As human beings, we descended from a lineage that literally survived in the ashes of the once glorious kingdom of dinosaurs, and we are the only species on the planet ever capable of such an event for the benefit of to learn ourselves and every other organism in our world. "