14 DAY TRIAL // The first dinosaur fossils were recognized in the nineteenth century, and quickly began to represent a major attraction for museum visitors, and spawned a whole culture among children and adults, featuring in different movies and best-seller books.
Dinosaurs formed one of the most successful groups ever to live on Earth. They have dominated the Earth's ecosystem for more than 160 million years only till they suddenly disappeared 65 million year ago, fact that might have allowed for humans to evolve.
They came in different shapes and sizes, from the smallest - the size of a chicken, under 60 centimeters tall - , to animals as long as 38 meters, weighing one hundred tons. Nevertheless, after the mass extinction of the dinosaurs, some vertebrate species managed to survive, like different species of birds, lizards, crocodiles and mammals.
There have been a number of theories regarding the mass extinction that took place 65 million years ago, the most popular of which is the asteroid collision scenario. In the 1970s, the extinction event is linked to a large under see crater, 170 kilometers wide, near the peninsula of Yucatan. For years, the large crater remained unobserved, but as soon as it was discovered, it triggered a lot of intrigue about how large the body that struck the Earth was, and what the consequences of such an event would be.
Some scientists sustained that the rock that hit the Earth, must have been about 5 to 15 kilometers wide, and could have triggered an atmospheric temperature drop that would be fatal to most of the species living on Earth, or possibly a heat wave with similar consequences. The initial blast wave could have killed most of the creatures living on the American continent, the rest being affected by the repercussions evolving from such an event.
Similar theories involve multiple collisions, from a comet disintegrating in the Earth atmosphere.
A novel theory though, is odder than anyone could think, and is related to an event that might have taken place 10.000 light years away from Earth. Astronomers propose that the event that triggered the death of two-thirds of all species on Earth might be related to a supernova explosion that occurred 440 million years ago, and has showered the Earth with deadly subatomic particles, that altered the chemistry of the atmosphere making life impossible.
This result has been found as a study of the sea floor sediments, that reveal an event taking place in the Pliocene era, 4 million years ago. The iron-60 isotope suggests that the supernova explosion might have actually taken place somewhere between 60 and 300 light years away, but scientists believe that this event taking place is highly improbable, since the Earth's atmosphere would have been severely weakened, allowing even more deadly ultraviolet radiation from the Sun to hit Earth's surface, which would have destroyed all chance of life evolving at the rate that would have allowed us to appear.