Dinosaurs - Before The Asteroid Struck

May 1, 2016 By Aarathi
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Museums, books, and movies have shown us how dinosaurs dominated life on earth for many millions of years before they were wiped out.

The reason for their extinction has been largely narrowed to a giant asteroid impact which triggered a series of irreversible changes on Earth. Over 75% of all plant and animal species in existence then were destroyed.

However, new research from the Universities of Reading and Bristol show that dinosaurs were already in decline before the asteroid hit. Their evolution was slowing down and this made them more vulnerable. They couldn’t adapt to the extreme changes in their environments caused by the impact of an asteroid and soon, all but vanished.

The Dinosaur Era

The word ‘dinosaur’ translates to ‘terrible lizard’, but that’s not technically correct.

Dinosaurs are now classified as a separate group of reptiles. They were extinct well before the evolution of the earliest humans, so we owe all our knowledge today to dinosaur fossils, which are found world-over. Paleontologists are scientists who study fossils and together with evolutionary ecologists, have traced back the history of this diverse group of animals.

Around 230 million years ago, during the late Triassic period, the Earth had one large unified continent called Pangaea. As this landmass started breaking up into smaller continents, changes in climate and environment encouraged the growth and evolution of dinosaurs. Eventually, they came to dominate all terrestrial ecosystems in the subsequent Jurassic and Cretaceous periods. Some species even took to the air and to water. Indeed, fossils have proved that modern-day birds descended from the dinosaurs!

The incredible variety of the dino species has fascinated researchers and enthusiasts alike. The animals consisted of both herbivores and carnivores. In size, they measured from just a few inches long to over 130 feet! Many had distinctive features like armor plates, frills, crests, spines, and horns. Some species walked on two hind legs, some moved on all fours, while yet others could switch between the two. And discoveries of new fossils still keep coming in!

What Caused Their Decline?

The asteroid is believed to have collided with Earth about 66 million years ago and the effects were devastating. It was believed that dinosaurs were not able to cope with the changes, resulting in a mass extinction along with many other groups of animals. You can read more about mass extinction here.

However, fresh research has added another angle to this crisis. The scientists conducted an intensive statistical analysis of dinosaur species and realized that the animals were on a decline 50 million years before the asteroid struck. In other words, the dinosaur species were dying out faster than new species could evolve. The asteroid impact was the final blow. 

Additionally, the team found that different groups of dinosaurs did not share a decline loss – some were falling much faster than others. The main reason for this loss of evolution capability is still unknown. However, the slowdown of evolution, in general, is of great concern. With many species disappearing now, scientists worry that human activity could soon cause another mass extinction.