World's Oldest Fossilized Sperm Found in Australia
Posted on May 14, 2014
Scientists have found the world's oldest fossilized sperm in Australia. The giant sperm, which belonged to a tiny shrimp species, is at least 17 million years old. The giant sperm were probably longer than the ancient shrimp's body. They were kept tightly coiled in the sex organs of the ostracods. The nuclei in each sperm (dark spot) are indicated by arrows in the above cross-section of an ostracod sperm fossil. The sperm fossils were found at the Riversleigh World Heritage Fossil Site in Queensland by researchers that included scientists from the University of New South Wales (UNSW).
Professor Mike Archer, of the UNSW School of Biological, Earth and Environmental Sciences, says in a statement, "These are the oldest fossilised sperm ever found in the geological record. The Riversleigh fossil deposits in remote northwestern Queensland have been the site of the discovery of many extraordinary prehistoric Australian animals, such as giant, toothed platypuses and flesh-eating kangaroos. So 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. It now makes us wonder what other types of extraordinary preservation await discovery in these deposits."
A microscopic study revealed that the fossils contain nearly perfectly preserved giant sperm cells and nuclei that contained the shrimp's chromosomes and DNA. The shrimp lived in an ancient cave that was enriched by bat droppings. Scientists say a steady rain of bat poo may have aided mineralization of the soft tissues. The artwork above by Dorothy Dunphy, from the book Riversleigh, shows what the cave may have looked like. A Sydney Morning Herald story says 800 fossilized specimens were found and 23 of them had some soft tissue preserved in the limestone.
The image below shows a modern Australian ostracod, Newnhamia fenestrata.
The research paper is published here in the journal, Proceedings of the Royal Society B.
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