A team led by John Long, a paleontologist at the Museum Victoria in Melbourne, Australia, identified embryos in extinct, jawed fish from a group called Arthrodira, the predominant members of the class Placodermi. Placoderms were bony, heavily armored fish that lived about 380 million years ago, and were “the dominant form of vertebrate life on the planet for 70 million years,” Long said.
In 2008, Long’s group identified embryos in a pair of fish fossils from a deposit in the Gogo formation in Kimberley, Australia. Those fish were part of a group called ptyctodontids, which made up only a tiny portion of the Placodermi class. The discovery pushed back the origin of internal fertilization by 200 million years. The findings prompted the group to look for signs of internal fertilization in other Placoderm fossils from hundreds of samples in collections around the world.
They reexamined Gogo fossils from the Arthrodira group. In two of the fossils’ body cavities were smaller fish, originally presumed to be a well-preserved meal. But based on the position of the tiny fish and the similarity to the ptyctondontid finds, the group concluded that the tiny arthrodire fish were actually embryos. “Finding that first embryo was the key, the Rosetta stone for knowing what to look for,” Long said.
Next, boys being boys, (hat tip to all the female scientists out there who would be far too decorous to commit the following bad taste) they had to work out just HOW these early matings took place.
Then they had to show us.
Note the silly grin on the male’s face before followed by a confused look after. Perhaps males of most species have not evolved that much!
Also note the female superior position and the fact that she does all the work.
Information, images and many of the words gleaned from The Scientist.
With thanks to an unevolved EaGle who gave me the incentive to post this proof of evolutionary development.