Palaeontologists have used a particle accelerator to reveal for the first time the structure of 500-million-year-old fossilised embryos. The researchers harnessed powerful X-ray beams from a synchrotron particle accelerator to create three-dimensional scans of embryos from two worm-like species from the Cambrian period called Markuelia and Pseudooides. The scans revealed previously unseen growth mechanisms for the worms' segments and provided further evidence of their evolutionary significance, says Philip Donoghue of the University of Bristol, UK, who led the research team (Nature, vol 442, p 680). "This imaging technology is truly stupendous. It could revolutionise the study of fossils," he says....