Researchers found the world's oldest sperm has been preserved in a bat poo at the Bitesantennary Site in the Riversleigh World Heritage area of Queensland.
"Nobody has ever seen sperm fossilised like this before. This was the oldest sperm in the world. We get used to fossil bones and teeth, but we did not expect the soft tissues would also preserve for 17 million years, " Co-author Palaeontologist Prof. Mike Archer from the University of New South Wales told ABC said.
The giant sperm belonged to 17-million-year-old fossil of the tiny crustaceans known as ostracods.
"They're cute little guys. They have two little shells and if you look inside, it looks like a little crab tucked up inside desperate to avoid being seen by the rest of the world," Archer described the species.
Ostracods measure few millimeters long but they have complex reproductive system, which makes one-third of a male ostracods body. With this, they are known to have the longest sperm in the animal kingdom measuring one centimeter in length.
Archer noted the sperm was preserved in bat's poop because the site had a pool that was formerly enclosed with a cave where bats lived. He imagined the ancient female and male ostracods might be in the middle of mating when a torrential rain of bat droppings occurred. The pool, as it turned out, was loaded with phosphorus which can fossilised anything that fell on it.
"And it happened so fast that soft tissues apparently were preserved. "These guys were actively in a state of reproduction. They were going about it and then suddenly tables turned and all of a sudden all biological activity stopped and they were sent into the future as a time capsule just doing what they were doing," Archer said.
He shared the fossil found showed a sperm coiled inside the male ostracods. While the female ostracods fossil revealed sperm trapped in their large seminal receptacles.
"This amazing discovery is echoed by a few samples of exceptional soft-tissue preservation in fossil bat-rich deposits in France, hence the key to eternal preservation of soft tissues may indeed be some magic ingredient in bat droppings," Associate Prof. Suzanne Hand said.