Is this the first fossil of an embryo? Mysterious 609-million-year-old balls of cells may be some of the earliest evidence of animal life on Earth
- The fossils were found on a discovery site in Guizhou Province in southern China
- Researchers at Harvard University believe embryo belongs to a ‘Caveasphaera’
- It is not confirmed whether the fossil is an animal or just a ball of bacteria
A fossilised ball of ‘cells’ has left scientists disputing whether it could be the earliest known animal embryo – or just a cluster of bacteria.
Resembling a grain of sand, the fossil, which under a microscope appears to be hundreds of thousands of cells bunched together, is believed by some to be an early embryo.
The fossils were found on a discovery site called Doushantuo Formation in Guizhou Province in southern China, however it is not conclusive whether it was an animal or just a ball of bacteria.
Researchers at Harvard University believe the embryo belongs to a creature called Caveasphaera – that lived in China 609 million years ago.
A fossilised ball of ‘cells’ has left scientists disputing whether it could be the earliest known animal embryo – or just a cluster of bacteria
Having recently completed a study on hundreds of Caveasphaera fossils, using x-rays to create 3-D images, the researchers believe the cells could be a rudimentary version of the animal – or its relative.
If this is true it would offer scientists the chance to unveil missing details on our own evolutionary history, the origin of animals and how species evolved to be so genetically varied.
Andrew Knoll of Harvard University told The New York Times that the balls of cells were ‘certainly things not seen before’, adding ‘these things could be animals.’
As early fossils are often hard to distinguish, even from fully grown animals, the size of the tiny cell balls makes classifying it very difficult.
David Bottjer, a paleontologist at the University of Southern California told the publication: ‘We don’t have a smoking gun. “Are these animals?” is the question, and we’re still kind of saying, “Yeah, maybe, maybe not.”‘
Three-dimensional reconstruction of a Caveasphaera specimen, showing cell structures
All animals today develop from fertilised eggs which multiply to form a multicellular body.
Palaeontologists don’t have much information from before the ‘Cambrian explosion’ ,542 million years ago, on how the bodies of animals evolved to become multicellular, diverging into such different species.
However DNA from odd ‘disks’ of cells from around 580 million years ago suggested that genetic mutations over generations had led animals to develop from their humble beginnings.
Animals closest living non-animal relatives, single-celled protozoans, are mostly found in water today and do not develop a ‘body’ despite gathering in large colonies.
The new finding could help to piece together just when and how cells continued to multiply to the point where they became bodies.
Researchers say the first ancestor of all living animals, both you and your dog, lived around 750 million years ago, long before the hailed ‘Cambrian explosion’.
The fossil was removed from its limestone rock which was dissolved in a mild acid.
It revealed a cluster of cells which the Harvard researchers believe have striking similarities with a Caveasphaera animal in its early stages of development – the creature was found to form in an envelope like structure when x-rayed with nanotomography.