Scientists have unearthed the world’s oldest sperm at a fossil site in Australia. The 17 million-year-old sperm belongs to an ancient species of tiny shrimp that lived in the Australian outback. "These are the oldest fossilised sperm ever found in the geological record," says Professor Mike Archer, a scientist at the University of New South Wales. Archer has been excavating at the Riversleigh fossil site for more than 35 years, and researchers have previously discovered giant, toothed platypuses and flesh-eating kangaroos there.
The giant sperm is believed to be longer than the male shrimp’s entire body, and was found tightly coiled up inside the sexual organs of the fossilised freshwater crustaceans, known as ostracods. Researchers collected the fossil ostracods back in 1988, before passing them to specialists who realized they contained soft tissues and sexual organs. The incredible preservation could be the result of bat droppings inside a cave 17 million years ago. "Tiny ostracods thrived in a pool of water in the cave that was continually enriched by the droppings of thousands of bats," says Archer. It’s thought that the droppings helped with the mineralization of the soft tissues. Archer says the discovery was "totally unexpected" and it "now makes us wonder what other types of extraordinary preservation await discovery in these deposits."