New Light on 'World's Oldest Animal Fossils, Cells Found From 600 Million Years Ago

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A team of researchers, led by the University of Bristol, has uncovered that ancient fossils, thought to be some of the world’s earliest examples of animal remains, could in fact belong to other groups such as algae.

The Weng’an Biota is a fossil Konservat-Lagerstätte in South China that is around 600 million-years-old and provides an unparalleled snapshot of marine life during the interval in which molecular clocks estimate that animal groups had evolved.

However, all fossil evidence from this time has met with controversy.

This is a spiny acritarch from the Doushantuo biota imaged using synchrotron tomography. The affinities of these fossils are unknown.

Credit: John Cunningham, University of Bristol.

Dr John Cunningham from the University of Bristol’s School of Earth Sciences, said: “Dated at around 600 million years old, these rocks preserve an assemblage of microscopic fossils, perfectly-aged to be candidates for the oldest evidence of animal life.

“These fossils aren’t recognisable as remains of fully grown animals, but some resemble embryos, ranging from single cells to clusters of thousands.

This is a fossil alga from the Doushantuo biota imaged using synchrotron tomography. The specimen has been virtually cut to reveal the internal anatomy. These fossils are thought to be red algae.

This is a digital model of an embryo-like fossil from the Doushantuo biota. The structures in each cell shown in yellow have been interpreted by some palaeontologists as nuclei, though this has been controversial.

Credit: John Cunningham, University of Bristol