Titanosaurs were common at the time of the asteroid strike at the end of the Cretaceous Period 66 million years ago.
A new statistical analysis of dinosaur diversity shows that at the time of their extinction from an asteroid strike 66 million years ago they were not in decline.
Researchers from the University of Bath and the Natural History Museum London say dinosaurs may have continued to dominate the earth if the effects hadn’t happened.
Dinosaurs were widespread around the world at the time of the asteroid impact in late late year chalk Time occupied all of the continents on the planet and were the dominant animal form of most terrestrial ecosystems.
However, it is still debated among paleobiologists whether the diversity of dinosaurs decreased at the time of their extinction.
Statistical modeling
To answer this question, the research team collected a number of different dinosaur pedigrees and used statistical models to assess whether each of the main groups of dinosaurs could still produce new species at the time.
Their study, published in the journal Royal Society Open Sciencefound that dinosaurs were not in decline prior to the asteroid strike, contradicting some previous studies. The authors also suggest that without the effects, dinosaurs would have continued to be the dominant group of land animals on the planet.
The study’s lead author, Joe Bonsor, is a joint PhD student at the University of Bath’s Milner Center for Evolution and the Natural History Museum.
He said, “Previous studies done by others have used various methods to conclude that dinosaurs were extinct anyway because they were in decline towards the end of the Cretaceous.
“We show, however, that when you expand the data set to include newer dinosaur pedigrees and a broader set of dinosaur types, the results don’t all point to this conclusion – in fact, only about half do.”
Sampling bias
Because of gaps in the fossil record, it is difficult to estimate the diversity of dinosaurs. This can be due to factors such as: For example, what bones are preserved as fossils, how accessible the fossils are in the rock to be found, and the places paleontologists look for them.
Using statistical methods to overcome these sampling biases, the researchers looked at speciation rates in dinosaur families rather than just counting the number of species that belong to the family.
Joe Bonsor said, “The main point of our work is that it is not that easy to look at a few trees and make a decision. The large inevitable biases in the fossil record and lack of data can often indicate a decline in species. However, this may not be a reflection of the reality at the time.
“We may never know the true dinosaur evolution rates because the only way to know for sure is to fill in the gaps in the record to get the best answer, and we just don’t think we’re barely.” there are .
“Our data currently does not show that they were in decline. In fact, some groups such as hadrosaurs and ceratopsians flourished, and there is no evidence that they would have become extinct 66 million years ago had it not been for extinction.”
While mammals existed at the time of the asteroid strike, it was only the dinosaurs’ extinction that resulted in the niches being cleared so that mammals could fill them and later dominate the planet.
Reference: “Dinosaurs Diversification Rates Did Not Decrease Before the K-Pg Limit” by Joseph A. Bonsor, Paul M. Barrett, Thomas J. Raven, and Natalie Cooper, 18th November 2020, Royal Society Open Science.
DOI: 10.1098 / rsos.201195
The research was funded by the Leverhulme Trust and Natural History Museum.
