A new statistical analysis of dinosaur diversity shows that they were not degraded when they were destroyed by an asteroid that struck 66 million years ago.
Researchers at Bath University and the Museum of Natural History in London say that if this effect did not occur, dinosaurs could continue to dominate the Earth.
Dinosaurs were widespread globally during the end of the asteroid impact Chalk period, occupied every continent of the planet and dominated the animal form of most terrestrial ecosystems.
However, it is still debatable among paleobiologists whether there was a decrease in the extinction of dinosaurs.
To address this question, the research team collected a number of different dinosaur generation trees and used statistical modeling to assess whether each of the major dinosaur groups could still produce new species.
Studies published in the journal Royal Society Open Science, contrary to some previous research, found that dinosaurs did not land before the asteroid hit. The authors also believe that in the absence of impact, dinosaurs could continue to be the dominant group of terrestrial animals on the planet.
The lead author of the study, Joe Bonsor, is pursuing a doctoral dissertation at the Milner Evolution Center and the Museum of Natural History at the University of Van.
He said: “Previous research by others has used a variety of methods to conclude that dinosaurs will already be extinct by the end of the Cretaceous period.
“However, if you expand the database to include newer dinosaur family trees and a wider dinosaur species, the results don’t actually all point to that result – in fact, only half of them show it.”
It is difficult to estimate the diversity of dinosaurs due to gaps in the fossil record. This may be due to factors such as the preservation of the bones as fossils, how accessible the rock is to allow the fossils to be found, and where the paleontologists are looking.
Instead of calculating the number of species in this family, the researchers looked at the specificity of the dinosaur families and used statistical methods to eliminate this sampling error.
Joe Bonsor said: “The main point of our article is that it is not as simple as looking at a few trees and making a decision – large unavoidable prejudices and lack of information in the fossil record may often indicate a species decline, but this may not be a reflection of reality at the time.
“We can never know the true evolutionary speeds of dinosaurs, because the only way to know for sure is to fill in the blanks in the records to get the best answer, and we just don’t think we’re there yet. .
“Our data does not show that they are currently in decline, in fact some groups, such as hadrosaurs and ceratopsians, were evolving, and there is no evidence that they would have died 66 million years ago if extinction had not occurred.”
Although mammals existed when an asteroid was hit, it only allowed the niches to empty due to the extinction of the dinosaurs, and the mammals to fill them and then dominate the planet.
Reference: “Dinosaur diversification rates did not decrease before the K-Pg boundary” Joseph A. Bonsor, Paul M. Barrett, Thomas J. Raven and Natalie Cooper, November 18, 2020, Royal Society Open Science.
DOI: 10.1098 / rsos.201195
The study was funded by the Leverhulme Trust and the Museum of Natural History.