First came sex, then came what fish do

THE world's earliest fish species had sex in what we now consider the traditional manner, an Australian researcher announced today.

Palaeontologist Professor John Long discovered spawning was a later result of evolution, and that male placoderms used "claspers" to cling onto females and let nature take its course through internal fertilisation.

The primitive armoured fishes invented copulation about 385 million years ago in Scotland, Prof Long said.

"With their arms interlocked, these fish looked more like they were square dancing the dosido rather than mating," he said.