A timescale for placental mammal diversification based on Bayesian modeling of the fossil record

Emily M Carlisle*, Christine M Janis, Davide Pisani, Philip C J Donoghue*, Daniele Silvestro*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)

Abstract

The timing of the placental mammal radiation has been the focus of debate over the efficacy of competing methods for establishing evolutionary timescales. Molecular clock analyses estimate placental mammals originated before the Cretaceous-Paleogene (K-Pg) mass extinction, anywhere from the Late Cretaceous to the Jurassic. However, the absence of definitive fossils of placentals before the K-Pg boundary is compatible with a post-Cretaceous origin. Nevertheless, lineage divergence must occur before it can be manifest phenotypically in descendent lineages and, therefore, detectable in the fossil record. This, combined with the non-uniformity of the rock and fossil records, requires the fossil record to be interpreted rather than read literally. To achieve this, we introduce an extended Bayesian Brownian Bridge model that estimates the age of origination and, where applicable, extinction through a probabilistic interpretation of the fossil record. The model estimates origination of placentals in the Late Cretaceous, with ordinal crown-groups originating at or after the K-Pg boundary. The results reduce the plausible interval for placental mammal origination to the younger range of molecular clock estimates. Our findings support both the Long Fuse and Soft Explosive models of placental mammal diversification, indicating that the placentals originated shortly prior to the K-Pg mass extinction. The origination of many modern mammal lineages overlapped with and followed the K-Pg mass extinction.
Original languageEnglish
Pages (from-to)3073-3082.e3
JournalCurrent Biology
Volume33
Issue number15
Early online date27 Jun 2023
DOIs
Publication statusPublished - 7 Aug 2023

Bibliographical note

Funding Information:
E.C. is funded by a studentship from the University of Bristol . P.C.J.D. received funding from the Biotechnology and Biological Sciences Research Council ( BB/T012773/1 ) and the Leverhulme Trust ( RF-2022-167 ). P.C.J.D. and D.P. received funding from the John Templeton Foundation (Grant 62220 ; the opinions expressed in this publications are those of the authors and do not necessarily reflect the views of the John Templeton Foundation). D.S. received funding from the Swiss National Science Foundation ( PCEFP3_187012 ), the Swedish Research Council (VR: 2019-04739 ), and the Swedish Foundation for Strategic Environmental Research MISTRA within the framework of the research program BIOPATH ( F 2022/1448 ). We are grateful to Ruolin Wu for feedback on the methods presented here. We wish to thank Nate Upham, Matt Jones, and two anonymous reviewers for providing comments that greatly improved the manuscript.

Publisher Copyright:
© 2023 The Author(s)

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