Scientists have discovered 117 million-year-old preserved giant sperm from tiny shrimp at the Riversleigh World Heritage Fossil Site in Queensland, Australia.
Researchers found that the fossil ostracods (fossilized freshwater crustaceans) collected at the site in 1988 actually contained preserved internal organs, including sexual parts with preserved giant sperm cells inside them. These remains had the nuclei that stored the animals' chromosomes and DNA. The Zenker organs - chitinous-muscular pumps that were used to transmit the giant sperm to the females - were also found in a preserved state.
The fossil sperm cells are estimated to be around 1.3 millimeters long, and are believed to be just as long as the ostracods - or even a bit longer. They were inside the sexual organs in tight coils, however.
The fossil ostracods were first collected by a University of New South Wales research team headed by Professor Mike Archer from the UNSW School of Biological, Earth and Environmental Sciences, Associate Professor Suzanne Hand, and Henk Godthelp from the Bitesantennary Site at Riversleigh. They sent the findings over to John Neil, a specialist ostracod researcher at La Trobe University. Neil made the conclusion that they had fossilized soft tissues inside them, and alerted European specialists Dr. Renate Matzke-Karasz from Ludwig Maximilian University in Munich, Germany and Dr. Paul Tafforeau of the European Synchotron Radiation Facility in Grenoble, France.
"About 17 million years ago, Bitesantennary Site was a cave in the middle of a vast biologically diverse rainforest. Tiny ostracods thrived in a pool of water in the cave that was continually enriched by the droppings of thousands of bats," Professor Archer explained in a university news release.
Professor Hand, who specializes in extinct bats and their role in Riversleigh's ancient environments, added that the bats' constant droppings in the cave may have contributed to the mineralization of the soft tissues.
Further details of the study were published in the Proceedings of the Royal Society B.
