A new scanning technique reveals previously unseen structures in fossilised embryos.
Scientists have used an X-ray imaging technique with resolutions down to the micron level - a thousandth of a millimetre - to look at fossilised embryo cells.
Philip Donoghue from the University of Bristol and his team used the technique called synchrotron-radiation X-ray tomographic microscopy or SRXTM. Hundreds of X-ray images are taken as the specimen is rotated and then a computer reconstructs a colourful three-dimensional image.
These fossilised embryos have fascinated scientists for a long time. The embryos are from animals living in the Cambrian period around 500 million years ago - a time when the first fossil records of modern animal groups appear.
'It is almost incredible to see the detail preserved inside these embryos, which date back to the early radiation of animals,' said Richard Fortey, Scientific Associate at the Natural History Museum.
Getting such detailed images at this resolution has previously been impossible without damaging the cells . The team predict this X-ray imaging technology will revolutionise the study of fossils and morphology in general.
The detailed SRXTM images allowed Donoghue's team to observe new aspects of early worm development , including a new pattern of segment formation in a developing embryo, not seen before in living animals.
The team have found out more about how creatures from the Cambrian were related - they confirmed that the worm-like species Markuelia is a close relative of the common ancestor of nematodes and arthropods.
Richard adds 'The combination of new fieldwork and exploration with cutting edge microscopic techniques shows that there is still potential to make major new discoveries in the fossil record.'
The research is published in the journal Nature