The first animals to get it on were called Microbrachius dicki , and they got it on in Scotia.
A new paper in science journal Nature claims that the first animals to reproduce through sex were small bony fish that lived in Scotland about 350 million years ago.
Whereas their ancestors reproduced by laying eggs and fertilising them later, the species Microbrachius dicki took to copulating genitally instead.
Dr Brian Choo, Flinders University / via Nature
"They couldn't have done it in a 'missionary position'," Professor John Long, the paper's lead author, told the BBC. Instead, they had sex side-by-side, linking their fins to keep from floating apart in the water.
Microbrachius dicki locked their genital appendages together using the female's genital plates, which were "very rough like cheese graters", and transferred sperm directly from the male to the female.
Dr Brian Choo, Flinders University / via Nature
Here is a recreation of Microbrachius dicki's fishy, pioneering love.
vine.co / Via nature.com / Flinders University
Professor Long made the discovery while rooting through an old box of fossils. He noticed that the M. dicki samples had strange L-shaped appendages, which later turned out to be male genitals.
"We have defined the very point in evolution where the origin of internal fertilisation in all animals began," he said.
However, the team behind the research think that this sexual revolution may have been a one-off. Later fish reverted to spawning as a reproduction method, and penetrative sex wasn't seen for another couple of million years, when the ancestors of modern sharks and rays took up the practice again.
