British researchers have found a fossil with what they claim is the earliest clear example of a male animal. The fossil was found in vulcanic ash in Britain and is well conserved according to them. It's an 425 million years old ancestor of modern water fleas:
It shows that ostracodes -- extremely common water-dwelling creatures -- have evolved little in hundreds of millions of years, said David Siveter of the University of Leicester. He and colleagues named it Colymbosathon ecplecticos, which means "swimmer with a large penis."Source: Reuters
Siveter, in a telephone interview, said the 0.2-inch creature probably lived on marine shelves, about 500 to 650 feet deep.
"This crustacean clearly could swim," said Siveter.
And there was another striking feature, he added.
"It is certainly the oldest penis in the world, that's for certain."
He said fossils as old as 520 million years show dimorphism -- differences in anatomy seen between males and females. But there has been contention over which examples may be female and which male.
"In this case we clearly have a male," he said.
The fossil, preserved in volcanic ash, is so intact that the gut and even the anus can be clearly seen.
"It was probably a ... scavenger and predator," the researchers wrote in Friday's issue of the journal Science.
Other clues suggest the crustacean also had a heart and an integrated circulatory system, they said, with the first firm evidence of gills in such an old species.
Siveter said thousands of species of ostracods, the most common arthropod in the fossil record, exist around the world today. They are shrimplike animals with a two-part protective shell and can be found in ponds, lakes, rivers and seas.
The 425 million-year-old animal lived in what is called the Silurian period, when the first land plants appeared but when algae still dominated the seas. Fish were beginning to evolve.