A new study found that dinosaurs were not in the fall before asteroids, instead the condition of the bad fossil and unpublished late cratesius rock layers means that they are either not protected or difficult to find.
It has long been indicated by fossil discoveries that dinosaurs were shrinking in numbers and variety before the asteroid effect at the end of the cracheus period, Live science,
Some researchers believed that it was a sign that dinosaurs were already on the road to extinct the catalasmic encounter with a space rock.
However, other researchers argued that the dinosaur diversity had been fixing at the time of his death, the idea had long been controversial.
The new research published in The Journal Current Biology on Tuesday suggested that the clear rarity of dinosaurs before his extinction could be just due to a poor fossil record.
A record scientists of about 8,000 fossils were studied from North America from Campion aged (83.6 million years ago) and Mastrician ages (72.1 million years ago).
He focused on four families: Ankilosoride, Ceratopside, Hadrosoride and Tyranosoride.
Their analysis at the inscribed value showed that the diversity of the dinosaurs was at the peak of about 76 million years ago, then shrunk until the asteroid strike wiped the Nonvian dinosaurs.
With the number of fossils of all four families in the geological records, this trend was even more pronounced in 6 million years before extinction.
However, researchers found that there is no indication of environmental conditions or other factors that would explain the decline.
