when did dinosaurs dead explain and who and why?????
i will mark you as BRAINLIST
Answers
Answer:
Sorry for answer so late
They lived 65 million years ago. Non-bird dinosaurs lived between about 245 and 66 million years ago, in a time known as the Mesozoic Era. This was many millions of years before the first modern humans, Homo sapiens, appeared. Scientists divide the Mesozoic Era into three periods: the Triassic, Jurassic and Cretaceous. Though the first dinosaurs appeared about 243 million years ago, they remain as prominent as ever today. Thanks to museums, books, and pop culture, dinosaurs remain larger-than-life. However, some cynics are not so sure that dinosaurs ever existed. A large comet or asteroid hit the earth. Thousands, if not millions of pieces from the asteroid travelled and each hit, one by one while the strong wind and fire from the asteroid wiped out million and millions of dinosaurs. Some did survive but then volcanic eruptions, floods, tsunamis, droughts, wildfires, storms, lack of oxygen, a lot of carbon dioxide, no sunlight and no trees caused the dinosaurs to die.
if too short...
The ground shook. Powerful gusts roiled the atmosphere. Debris rained from the sky. Soot and dust, spewed by the impact and resulting wildfires, filled the sky. That soot and dust then began to spread like a giant sunlight-blocking shade over the entire planet. How long did the darkness last? Some scientists had estimated that it was anywhere from a few months to years. But a new computer model is giving researchers a better sense of what happened. It simulated the length and severity of the global cooldown. And it must have been truly dramatic, reports Clay Tabor. He works at the National Centre for Atmospheric Research in Boulder, Colo. As a paleo climatologist, he studies ancient climates. And he and his colleagues have reconstructed a sort of digital crime scene. It was one of the most detailed computer simulations ever made of the impact’s effect on climate. The simulation begins by estimating the climate before the smash-up. The researchers determined what that climate might be from geologic evidence of ancient plants and levels of atmospheric carbon dioxide. Then comes the soot. A high-end estimate of soot totals some 70 billion metric tons about 77 billion U.S. short tons.
not helpful. No problem.
Well, their whole period of existence was called the Mesozoic period. The earliest dinosaurs such as Coelophysis, a predator, appeared in the sub-period called the Triassic, from around 225 million BC to 190 million BC. By the way, Coelophysis was from the late Triassic. Then in the Jurassic period, 210 million BC to 140 million BC as they overlapped slightly, probably the best well known period from the movie 'Jurassic Park', which in fact most of the dinosaurs in it came from the next period, then again the late Jurassic sauropods, like Brachiosaurus, you might know it as Brontosaurus, because it was discovered later and named again but the scientific name is Brachiosaurus were widespread, so the Jurassic is sometimes known as 'the age of the giants'. Next came the Cretaceous period, from 135 million BC until 65 million BC, when all the well known dinosaurs existed, such as T. Rex, Velociraptor, Triceratops, Stegosaurus Etc. Now most of the sauropods had died out, except from the titanosaurians, the really big dinosaurs like Argentinosaurus, one of the largest animals to ever walk this planet. But then in something known as the Cretaceous-Tertiary event, then the dinosaurs became extinct, from known paleontological evidence as quite suddenly. So what happened? No-one knows. And we may never know. But we have some quite good theories, such as perhaps a meteorite, a huge one, around the size of 10km. Then perhaps another comet arrived, to tip the dinosaurs over the edge into extinction. But how would this affect the dinosaurs? Well there is a theory that the impact created a huge amount of dust, enough to block out the sunlight from the Earth. This would then kill plants, killing herbivores, killing carnivores. And the only thing to survive it were some of the smallest things on the planet, the things that could hide in tiny holes to avoid the dust... the mammals. It was the start of a new age... the Tertiary age, which we are still in now. In 1859, the first scientifically documented dinosaur egg fossils were discovered in France by Jean-Jacques Poech, although they were mistaken for giant bird eggs. The first scientifically recognized dinosaur egg fossils were discovered in 1923 by an American Museum of Natural History crew in Mongolia.