All dinosaurs including the Tyrannosaurus Rex, Triceratops and Velociraptors were going instinct millions of years before the catastrophic asteroid wiped them off the face of the earth. Researchers were surprised by their findings especially after finding out that the dinosaurs were unable to evolve new species when old species were dying out fast.

The study published in the journal Proceedings of the National Academy of Sciences observed dinosaurs and their lineage using fossil data and statistics with the help of a computer. While it was previously believed that the giant asteroid that hit the earth 66 million years ago made the dinosaurs go extinct, researchers say that they were in the process of dying out before then.

5 (sometimes weird) theories of what killed the #dinosaurs: https://t.co/vAYL72T3ku

— National Geographic (@NatGeoMag) April 19, 2016

"While the asteroid impact is still the prime candidate for the dinosaurs' final disappearance, it is clear that they were already past their prime in an evolutionary sense," Paleontologist Dr. Manabu Sakamoto of University Reading said in a statement. Dr. Sakamoto adds that while the asteroid was the last straw in the extinction of dinosaurs, there were other factors that hindered the species from continually thriving.

Researchers don't know what caused dinosaurs to not evolve or decline in diversity. The Washington Post notes that it may be due to climate change where the cooling weather may have affected the dinosaurs. Co-author Mike Benton of University of Bristol adds that the cooling and changing ecosystem may have hindered the dinosaurs from recovering "from the environmental crisis caused by the impact," Yahoo reports. However, Stephen Brusatte from University of Edinburgh said that while the dinosaurs were going instinct, there was no way that they could have survived the asteroid impact, Atlantic notes. 

How do you think dinosaurs went extinct? Share your theories in the comments below.