Scientists shed new light on the timeline of mammal evolution

A new study led by Queen Mary University of London, University of Bristol, and University College London (UCL) has provided the most detailed timeline of mammal evolution to date. By using a novel computational approach, the researchers confirmed that modern mammal groups originated after the Cretaceous-Paleogene (K-Pg) mass extinction, offering a new perspective on a long-standing controversy in evolutionary biology.

Large genomic datasets are essential for understanding the evolution of species. However, analysis of such enormous datasets can be slow and require a large amount of computational power. 

“Inferring evolutionary timelines is a fundamental goal of biology. However, state-of-the-art methods rely on using computers to simulate evolutionary timelines and assess the most plausible ones. In our case, this was difficult due to the gigantic dataset analyzed, involving genetic data from almost 5,000 mammal species and 72 complete genomes,” said study lead author Dr. Mario dos Reis, a senior lecturer in Biology at Queen Mary University.

Dr. dos Reis and his colleagues developed a new, fast Bayesian approach to analyze large numbers of genomic sequences, while also accounting for uncertainties within the data. Without this innovative method, which helped scientists reduce computation time by a factor of 100, inferring the mammal evolutionary trees from the available data would have taken several decades. 

“This new approach not only allows the analysis of genomic datasets, but also, by being more efficient, substantially reduces the CO₂ emissions released due to computing,” said study co-lead author Dr. Sandra Álvarez-Carretero, a postdoctoral researcher at UCL.

The findings confirm that the ancestors of modern placental mammal groups postdate the K-Pg extinction that occurred 66 million years ago and wiped-out 70 percent of all species.

“The timeline of mammal evolution is perhaps one of the most contentious topics in evolutionary biology. Early studies provided origination estimates for modern placental groups deep in the Cretaceous, in the dinosaur era. The past two decades had seen studies moving back and forth between post- and pre-K-Pg diversification scenarios. Our precise timeline settles the issue,” explained study co-senior author Phil Donoghue, a paleontologist at the University of Bristol.

The method developed in this study could be used in future research to shed more light on other contentious evolutionary timelines that require analysis of large datasets. 

The study is published in the journal Nature.

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By Andrei Ionescu, Earth.com Staff Writer