SYDNEY - The world's oldest and best-preserved sperm, dating back 17 million years, has been unearthed in Australia, scientists said Wednesday.
The sperm from an ancient species of tiny shrimp was discovered at the Riversleigh World Heritage Fossil Site, an area in the far north of the state of Queensland where many extraordinary prehistoric Australian animals have previously been found.
They include giant, toothed platypuses and flesh-eating kangaroos.
Mike Archer, from the University of New South Wales School of Biological, Earth and Environmental Sciences, who has been excavating at Riversleigh for 35 years, said the sperm was an exciting find.
"These are the oldest fossilised sperm ever found in the geological record," he said.
The sperm are thought to have been longer than the male's entire body, but were tightly coiled up inside the sexual organs of the fossilised freshwater crustaceans, known as ostracods.
"We have become used to delightfully unexpected surprises in what turns up there," he added of Riversleigh.
"But the discovery of fossil sperm, complete with sperm nuclei, was totally unexpected. It now makes us wonder what other types of extraordinary preservation await discovery in these deposits."