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| In this artist rendition released by Peter Trusler, Placoderms are depicted mating in what once was a giant lake in southern Australia [Credit: Peter Trusler/AP] |
Dr John Long, a paleontologist based at the Natural History Museum of Los Angeles County in the US, said that unlike other pre-historic fish, these Aussies got physical to reproduce.
"Well, you know we've been a nation of not very romantic blokes and someone had to start it," the scientist originally from Australia told AAP on Monday.
The preserved fossils were found at the Gogo site, in Western Australia, in 2005.
Placoderms died out 350 million years ago at the end of the Devonian period but for 70 million years they were the most prolific life form on earth.
Their style of romantic sex was happening some 200 million years before the arrival of mammals.
"It must have been enjoyable or they wouldn't have done it, or they would have become monks," Dr Long said.
"These fish were copulating. It was the beginning of love, if you want to define love that led to courtship.
"We know for sure these things had intimate ways of mating."
Dr Long, the vice-president of research and collections at the American museum, said the fossils had perfectly preserved embryos.
This suggested the placoderms mated intimately so the female could give birth in the water to a small number of young.
This kind of behaviour was an evolutionary step from other fish, which reproduced by having the male fertilise thousands of eggs that had been laid in the water.
In an evolutionary step from the placoderms, male sharks have soft claspers that become erect with sexual arousal.
Their sex lives may be more advanced but their genitalia don't preserve as well as their placoderm ancestors.
Dr Long is speaking at the Australian Museum in Sydney on Monday night and is signing copies of his book, Hung Like An Argentine Duck.
Source: SBS [April 02, 2012]