for National Geographic News
Using the world's largest microscope, paleontologists have peeked inside tiny fossils of 500-million-year-old embryos, each about the size of a grain of sand.
"These are extremely rare," said Philip Donoghue, a paleontologist at Britain's University of Bristol. "Studying them is a problem."
Previously the only way to find out what was inside such fossils was to slice them open and put them under a microscope.
Even if scientists were willing to do that, many fossils would be destroyed in vain. That's because most embryo fossils preserve only the outline of the animal, with nothing inside.
"But a few are really well preserved," Donoghue said.
The new technique allows the fossils to be scanned without damaging them.
Donoghue and his team report on their research in the current issue of the journal Nature.
World's Biggest Microscope
The fossil embryos were found in China and Siberia and are members of wormlike ancient species called Markuelia and Pseudooides.
(See the National Geographic magazine feature, "China's Fossil Marvels.")
Using the new technique, researchers have been able study the animals at a level of detail never before possible.
For example, Donoghue says, it's possible scan the length of a tiny worm's digestive tract, determining the shape of its organs and the arrangement of its teeth.
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