Fossilized Embryos Seen in Deep Detail

A new technique allowing virtual dissections of half-billion-year-old fossil embryos is producing the first three-dimensional images of the dawn of life.

“Because of their tiny size and precarious preservation, embryos are the rarest of all fossils,” said lead researcher Phil Donoghue of Bristol University in England. “But these fossils are the most precious of all because they contain information about the evolutionary changes that have occurred in embryos over the past 500 million years.”

In contrast to existing methods -- looking at the fossils’ exteriors, or slicing them apart -- synchrotron-radiation X-ray tomographic microscopy leaves the tiny fossils untouched but gives graphic details of their structure.

The team used a particle accelerator in Switzerland to deep-scan the minute fossils of ancient worm-like species. A computer generated complete 3D images of the internal structures in fine detail.

“The best analogy is with a medical CT scan” but at 2,000 to 3,000 times the resolution, Donoghue said. “We can see details less than 1,000th of a millimeter.”

“We can look at any and every part of the fossil -- inside and out -- without harming it and then virtually dissect it however we like,” he said.

The team, which published its findings Thursday in the journal Nature, said its discoveries could roll back the evolutionary history of arthropods such as insects and spiders.

In one case, they found details of the interior structure of an ancient relative of a modern-day worm species.

“The method has wide applicability in the study of microscopic structures ... and may thus bring about a revolution in paleontology on a par with that once brought about by the scanning electron microscope,” the researchers said.