Animals may have evolved hundreds of millions of years earlier than fossil evidence suggests

Amazing stuff!

"The earliest animals may have evolved hundreds of millions of years before their first unmistakable fossils appear in the fossil record, according to a new study led by the University of Oxford. The findings, published in Science Advances, suggest animals may have originated deep in the Neoproterozoic Era, even before some of the most extreme ice ages in Earth's history. ...

The research team ... carried out a comprehensive survey of exceptionally well-preserved microfossils from the Kheseen Biota in Mongolia. The Kheseen Biota is more than 40 million years younger than Weng'an, even though they share some species. By this time, animal fossils are known from sites elsewhere around the world, including Namibia and South China. ..."

From the 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."

Animals may have evolved vastly earlier than fossil evidence suggests

Re-evaluating molecular clock maximum age calibrations revives pre-Ediacaran divergence estimates for animals (open access)

Fig. 4. Comparison of recovered animal divergence estimates with varying maximum calibrations.