Thu, May 15, 2014 - Page 6 News List

Oldest sperm ever found in Australia after 17m years

STRONG SWIMMERS:An expert said the find was ‘delightfully unexpected’ since the fossilized sperm, from an ancient species of shrimp, was so complete


The world’s oldest and best-preserved sperm, dating back 17 million years, has been unearthed in Australia, scientists said yesterday.

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 Queensland State, where many extraordinary prehistoric Australian animals have previously been found, including flesh-eating kangaroos.

Mike Archer of the University of New South Wales School of Biological, Earth and Environmental Sciences, who has been excavating Riversleigh for 35 years, said the sperm was an exciting find.

“These are the oldest fossilized sperm ever found in the geological record,” he said.

The sperm are thought to have been longer than the male shrimp’s entire body, but were tightly coiled up inside the sexual organs of the fossilized freshwater crustaceans, known as ostracods.

“We have become used to delightfully unexpected surprises in what turns up there, but the discovery of fossil sperm, complete with sperm nuclei, was totally unexpected,” Archer said.

A research team led by Archer collected the fossils in 1988 and sent them to John Neil, a specialist ostracod researcher at La Trobe University in Melbourne, who realized they contained fossilized soft tissues.

He drew this to the attention of several European specialists and a microscopic study revealed the fossils contained the preserved internal organs of the ostracods, including their sexual organs. Within these were the almost perfectly preserved giant sperm cells and within them, the nuclei that once contained the animals’ chromosomes and DNA.

The researchers, whose findings are published in the journal Proceedings of the Royal Society B, estimate that the sperm are about 1.3mm long, slightly longer than the shrimp’s body.

Archer said that about 17 million years ago, the site where the fossils were found was a cave.

“Tiny ostracods thrived in a pool of water in the cave that was continually enriched by the droppings of thousands of bats,” he added.

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