First Sex on Earth? Yeah, This Is It!

A study published in Nature revealed what the first act of copulation looked like. The first ones to have penetrative sex were placoderms, armored fish that lived some 385 million years ago!

The species, found in Estonia, even has what someone might call an accurate name: Microbrachius dicki. (Let's just ignore the fact that it's actually named after Robert Dick).

Males had a pair of L-shaped limbs which they used to transfer sperm into females which had paired bones to keep the male's organ inside until the transfer was done.

Microbrachius stands for small arms and the animals were named when scientists didn't know what those 'arms' were used for. Now they know that they were used for copulation which was done sideways. The fish would swim next to each other, connected.

Oh, there's actually a video:

However, as we know, fishes these days spawn and don't copulte penetratively. Cartilaginous fishes, on the other hand, do have penetrative sex, so they were quite possibly the next in line to evolve genitals designed for coitus.

In 2018, a new species of the same genus, M. kedoae was found in Belarus.

Scientific name:	Microbrachius dicki
Phylum:	Chordata
Class:	Placodermi
Order:	Antiarchi
Family:	Microbrachiidae
Scientific reading: