Modern mammals originated after dinosaur extinction, confirms new study

Mammal tree of life - The mammal tree of life. Credit: Dr Mario dos Reis and Dr Sandra Álvarez-Carretero - The most detailed timeline of mammal evolution to date has been set out in a new study co-led by UCL researchers. The Nature paper describes a new and fast computational approach to obtain precisely dated evolutionary trees, known as 'timetrees'. The authors used the novel method to analyse a mammal genomic dataset and answer a long-standing question around whether modern placental mammal groups originated before or after the Cretaceous-Palaeogene (K-Pg) mass extinction, which wiped out over 70% of all species, including all dinosaurs. The findings confirm the ancestors of modern placental mammal groups postdate the K-Pg extinction that occurred 66 million years ago, settling a controversy around the origins of modern mammals. Placental mammals are the most diverse group of living mammals, and include groups such as primates, rodents, cetaceans, carnivorans, chiropterans (bats) as well as humans. Co-lead author Dr Sandra Álvarez-Carretero (UCL Genetics, Evolution & Environment), who began the research while based at Queen Mary University of London, said: "By integrating complete genomes in the analysis and the necessary fossil information, we were able to reduce uncertainties and obtain a precise evolutionary timeline.