In a new report published in the journal Nature, scientists shared their discovery that the first animals to have sexual intercourse did so by boning side to side instead of missionary style. The fish creatures were so daunted by their "cumbersome genitalia" that this was the only way they could procreate.

The Guardian reports that researchers at Flinders University in Australia learned of this sideways sex through studying fossils. The fish, called antiarchs, lived in lakes over 380 million years ago.

Are you ready to read a sentence about cheese graters? Stay with me:

Fossilised features of antiarch fish suggest that early intercourse was not the smoothest of affairs, with males faced with the task of steering their bony L-shaped organs between twin genital plates that adorned the females like tiny cheese graters.

But, there's more! The male fish were daunted by their genital size:

The male's organ was nearly as long as his body and fixed rigid, leading paleontologists to finally work out that the creature's small, jointed arm-like appendages were probably of help in achieving the correct position."Fundamentally, they could not have done it in the missionary position," said John Long, professor of palaeontology at Flinders University in Adelaide. "The very first act of copulation was done sideways, square-dance style."

For years, scientists couldn't figure out what these little fish species used their tiny arms for, but now they know: it helped them lock together when sexing sideways.

If you are not sufficiently spooked, here is a helpful video simulation:

[Image via Flinders University]