Scientists believe they have discovered the origin of copulation.
An international team of researchers says a fish called Microbrachius dickiis the first-known animal to stop reproducing by spawning and instead mate by having sex.
The primitive bony fish, which was about 8cm long, lived in ancient lakes about 385 million years ago in what is now Scotland.
The research is published in the journal Nature.
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They couldn’t have done it in a ‘missionary position’”
Prof John LongFlinders University
Lead author Prof John Long, from Flinders University in Australia, said: “We have defined the very point in evolution where the origin of internal fertilisation in all animals began.
“That is a really big step.”
Prof Long added that the discovery was made as he was looking through a box of ancient fish fossils.
He noticed that one of the M. dicki specimens had an odd L-shaped appendage. Further investigation revealed that this was the male fish’s genitals.
“The male has large bony claspers. These are the grooves that they use to transfer sperm into the female,” explained Prof Long.