Scientists: Dinosaurs became extinct the second time
Secrets of the past: Dinosaurs became extinct the second time. Scientists cast doubt on theory of dinosaur extinction as a result of falling to Earth asteroid
It is believed that the extinction of the dinosaurs occurred as a result of falling to Earth a huge asteroid about 65 million years ago. However, scientists from the University of Washington believe that before the asteroid collision with the Earth occurred another event that influenced the disappearance of the giant lizards: a volcanic eruption destroyed the ocean life, mainly mollusks and snails.
«The eruption started in around 300 – 200 thousand years until the asteroid and lasted, probably, for 100 thousand years,» the Daily Mail quoted Dr. Thomas Tobin. Thus the atmosphere stood out carbon dioxide and other greenhouse gases, which in turn led to the warming and the first of the two extinctions. In the course of a vanished life at the bottom of the ocean; and during the next, caused by an asteroid impact, killed the other waterfowl species.
The studies were conducted in rich fossil deposits of the region on the island of Seymour, the study of which allows to determine what happened during the mass extinctions.
The experts collected small samples of rock and fossils and with the help of magnetostratigraphy have determined the time of their appearance. «I think that the evidence indicates two different events, including warming,» says Dr. Tobin.
Although there is currently no direct evidence that the first mass extinction had an effect on the second, experts believe that the survival of the species by that time was already on the verge, so the asteroid to survive the dinosaurs already failed. «It’s incredible that these two mass extinctions can be completely independent events,» added Thomas Tobin, materials .