Work

Re-evaluating molecular clock maximum age calibrations revives pre-Ediacaran divergence estimates for animals

Year: 2026

Type: article

Abstract: Divergent models persist for the emergence of animals. Lipid biomarkers suggest animals originated before 635 million years ago (Ma), but their body fossil record extends to only 574 Ma. Molecular clocks might differentiate between these records, but we demonstrate how their accuracy and precision hinge on maximum age calibrations. We evaluate the Ediacaran Weng'an Biota (China) as a maximum calibration utilizing microfossils from the Kheseen Biota (Mongolia). These two biotas have similar preservation and microfossil assemblages, containing no definitive animals. The Kheseen Biota, deposited at a time (∼550-526 Ma) when animals were undoubtedly present, questions the validity of the Weng'an calibration. We discuss the uncertainty in maximum calibration strategies and propose multiple pre-Ediacaran deposits with favorable taphonomy, preserving both non-animal body fossils and biomarkers, as currently the most reliable calibrations. Our analyses support a late Tonian to mid-Cryogenian (∼800-700 Ma) origin for Metazoa.

Source: Science Advances

DOI: 10.1126/sciadv.aeg6289

Authors: Orin M. Lole Durbin, Eliel S.C. Anttila, Derek E.G. Briggs, Francis A. Macdonald, Ross P. Anderson

Institutions: University of Oxford, Virginia Tech, ETH Zurich, Robert S. Peabody Museum of Archaeology, University of California, Berkeley

Language: English

Topic: Evolution and Paleontology Studies

Subfield: Paleontology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,500

Funders: National Science Foundation, Royal Society, NASA Astrobiology Institute, All Souls College, University of Oxford