The question why non-avian dinosaurs went extinct 66 million years ago (Ma) remains unresolved because of the coarseness of the fossil record. A sudden extinction caused by an asteroid is the most accepted hypothesis but it is discussed whether dinosaurs were in decline or not before the impact. We analyse the speciation-extinction dynamics for six key dinosaur families, and find a decline across dinosaurs, where diversification shifted to a declining-diversity pattern ~76 Ma. We investigate the influence of ecological and physical factors, and find that the decline of dinosaurs was likely driven by global climate cooling and herbivorous diversity drop. The latter is likely due to hadrosaurs outcompeting other herbivores. We also estimate that extinction risk is related to species age during the decline, suggesting a lack of evolutionary novelty or adaptation to changing environments. These results support an environmentally driven decline of non-avian dinosaurs well before the asteroid impact.
Bibliographical noteFunding Information:
This project received funding from the Marie Curie International Outgoing Fellow under the European Union’s Seventh Framework Programme (project BIOMME, agreement No. 627684) and a PICS grant from the CNRS (project PASTA) to F.L.C.; from the NERC grant NE/ I027630/1 and European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (agreement No. 788203) to M.J.B.; from the NSERC grant 2017-04715 to P.J.C. The analyses benefited from the Montpellier Bioinformatics Biodiversity (MBB) platform services.
© 2021, The Author(s).