The theory on the dinosaur-killing asteroid hit, which many believe to have wiped out the prehistoric beasts 66 million years ago, no longer suffices as an explanation, as scientists came up with a study revealing that their extinction started earlier.
Researchers concluded that the number of dinosaurs was already decreasing even before the devastation that happened in the present-day Gulf of Mexico, based on their statistical analysis. The group was comprised of experts from England's University of Reading and the University of Bristol.
The issue on whether dinosaurs had been reigning strongly or had already been numerically challenged prior to their total disappearance has long been a subject of debate. Coming up with a resolution has been challenging due to lack of precision in the methods used.
"Paleontologists have discussed and argued in length over decades about whether dinosaurs were experiencing a long-term decline even before their final extinction," Manabu Sakamoto, the study lead author, from the University of Reading told The Christian Science Monitor.
According to the Proceedings of National Academy Sciences journal that published the results, species were disappearing faster than their emergence. This pattern is said to have started millions of years before their final extinction, as supported by a statistical procedure used specially for this study.
Statistical analysis was based on "family trees," from which three large ones were identified: the flesh-eating beasts or the theropods, the long-necked herbivores or the sauropods, and the long-beaked, plant-eating species or the ornithiscians.
Results further show that dinosaurs were rising in number during late Triassic period, or around 220 million years ago. This growth reached a plateau, however, paving the way for a significant, long-term decline 90 million years ago, more than two decades before the space rock hit the planet.
"If they continued on that trajectory, even if that meteor didn't hit, they may well have been very species-poor in some millions of years or even have gone extinct all together," researcher Chris Vendetti of the University of Reading said, according to The Guardian.