A new study by researchers at the University of Bath and the Museum of Natural History looking at the diversity of dinosaurs shows that they were not in decline at the time of their extinction by an asteroid that struck 66 million years ago.
If the impact had not occurred, the researchers say, the dinosaurs might have continued to dominate Earth.
Dinosaurs were spread all over the world at the time of the asteroid collision at the end of the Late Cretaceous, and they occupied every continent on the planet and were the dominant form of animals in most terrestrial ecosystems.
However, there is still disagreement among paleontologists over whether dinosaurs were declining at the time of their extinction.
To answer this question, the research team collected a collection of different dinosaur family trees and used statistical modeling to assess whether each of the major groups of dinosaurs was still capable of producing new species at this time.
Their study was published in the journal Royal Society for Open Science, It was found that the dinosaurs were not in a state of decline before the asteroid collision, which contradicts some previous studies. The authors also point out that had the effect not occurred, dinosaurs might have continued to be the dominant group of land animals on the planet.
The study’s first author, Joe Bunsoor, is jointly pursuing a PhD at the Milner Center for Evolution at the University of Bath and the Museum of Natural History.
He said, “Previous studies by others used different methods to arrive at the conclusion that dinosaurs were going to die anyway, because they were in decline with the end of the Cretaceous period.”
“However, we showed that if you broaden the dataset to include more modern dinosaur family trees and a wider range of dinosaur species, the results don’t actually point to that conclusion – in fact only half of them do.”
Dinosaur diversity is difficult to assess due to gaps in the fossil record. This could be due to factors such as bones preserved as fossils, how accessible the fossils are in the rocks to allow them to be found, and the sites that paleontologists are looking for.
The researchers used statistical methods to overcome these sampling biases, looking at the speciation rates of dinosaur families rather than just counting the number of species that belonged to the family.
Joe Boonsur said: “ The main point of our research paper is that it’s not as simple as looking at a few trees and making a decision – large, inevitable biases in the fossil record and lack of data can often show a decline in species, but this may not be a reflection of reality. at that time.
“Our data at the moment does not show that they were in decline. In fact some groups such as Hadrosaurs and Ceratopsians were flourishing and there is no evidence to suggest that they would have died 66 million years ago had the extinction not occurred.”
While mammals were present at the time of the asteroid collision, only the extinction of the dinosaurs led to the evacuation of the vents, allowing the mammals to populate them and subsequently take over the planet.
The research was funded by the Leverhulme Trust and the Natural History Museum.
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