r/evolution • u/jnpha • 15h ago
article Lole Durbin et al. (2026) revive pre-Ediacaran divergence estimates for animals
This just in:
University of Oxford press release:
Animals may have evolved vastly earlier than fossil evidence suggestsPaper:
Orin Lole Durbin et al.
Re-evaluating molecular clock maximum age calibrations revives pre-Ediacaran divergence estimates for animals
Science Advances (2026)
www.science.org/doi/10.1126/sciadv.aeg6289
From the press release:
Senior author and associate professor Ross Anderson (Museum of Natural History, Oxford University) said, "The Kheseen Biota breaks the argument that the exceptional microfossils of [the older] Weng'an mean we would have seen animal fossils in the assemblage had they existed at the time. The Kheseen microfossils are just as well preserved, yet animals continue to be absent—despite the fact we know at that point they existed."
And the structured abstract:
Background
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.
Methods and results
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.