Dinosaurs in decline before the asteroid strike

65 million years ago, an asteroid of about 10 km diameter struck the Yucatan Peninsula in the Gulf of Mexico, causing a mass extinction event that is the second biggest mass extinction in history (after the Permian mass extinction event 250 million years ago)

In a new research, it has been shown that dinosaurs might have been in decline millions of years prior to the infamous asteroid strike that took place 65 million years ago, which has been stipulated as the main reason why dinosaurs went extinct. Previous theories suggested that dinosaurs were quite dominant up to that point, with mammals gaining domination after the asteroid hit. 

However, startling new information has come to light. In previous years, new theories suggested that a few dinosaur species might have been one the decline a couple of million years before the asteroid strike. But, while examining records of various species of dinosaurs over the Jurassic and Cretaceous period, it was seen that species development declined rapidly after the early Cretaceous. 

The dinosaur species most in decline before the asteroid strike was the Sauropod, a group of dinosaurs which were herbivores and had very very long necks (for e.g. Argentinosaurus, Titanosaurus, Apatosaurus). The therapod dinosaurs (for e.g Tyrannosaurus Rex, Spinosaurus, Allosaurus), from which birds have evolved, showed a slower decline. 

Scientists predict that this decline was a result of the cooling climate. In the Triassic period, the geological age in which the dinosaurs evolved, temperatures were scorching high, because of the super continent Pangaea. However, as Pangaea broke up in to Eurasia and Gondwanaland, which further broke up, the climate cooled. Dinosaurs, being reptiles, could not adapt to the cooler climate. 

An interesting consequence of this is that mammals might have been dominant much earlier than expected. In the Mesozoic era, which literally means the era of reptiles, Dinosaurs were powerful and this restricted the capability of mammals. Mammals were hunted by the smaller Dinosaurs and they could not impose their dominance in the presence of Dinosaurs. However, once the number of Dinosaurs declined, mammals could stop hiding and establish themselves as dominant creatures by virtue of their adaptability to the cooler climate as well as increased “brain power”.