Ancient Scottish fish first to have sex, and sideways too, fossil find shows

Scientists studying fossils have discovered that the intimate act of sexual intercourse used by humans was pioneered by an ancient armoured fish, called a placoderm, about 385 million years ago in Scotland.

In an important discovery in the evolutionary history of sexual reproduction, the scientists found that male fossils of the Microbrachius dicki, which belong to a placoderm group, developed bony L-shaped genital limbs called claspers to transfer sperm to females.

Females, for their part, developed small paired bones to lock the male organs in place for mating. Placoderms are the earliest vertebrate ancestors of humans.

"Placoderms were once thought to be a dead-end group with no live relatives, but recent studies show that our own evolution is deeply rooted in placoderms and that many of the features we have - such as jaws, teeth and paired limbs - first originated with this group of fishes," said John Long, a palaeontologist at Flinders University in South Australia who led the research.

This new finding, he added, shows that "they gave us the intimate act of sexual intercourse as well".

Matt Friedman, a palaeobiologist from Britain's Oxford University who was not involved in the research, described its findings as "nothing short of remarkable" and said they suggested much more could be learned from the fossil fish.