Palaeontology: Girls and boys come out to play

To have and to hold

SEX is ubiquitous, but sexual intercourse is not. On dry land, it is more or less de rigueur. Sperm and eggs risk dessication otherwise. Mammals, birds and reptiles do it. Insects do it. Even snails do, it—firing darts at each other as part of the preliminaries. But many creatures live in the oceans, and a lot of them simply broadcast eggs and sperm into the water and hope that these will meet. Even those marine animals that do come together to mate—bony fish, for example—often employ external fertilisation. That has led researchers to assume that copulation, in which a male’s sperm are inserted into a female’s reproductive tract, and fertilisation takes place therein, is a derivative rather than an original characteristic of the vertebrate line that leads from the first jawed, bony fish to mankind.However, an extinct species with the name, perhaps unfortunate in context, of Microbrachius dicki, suggests otherwise. As they report in a paper just published in Nature, John Long of Flinders University, in Adelaide, and his colleagues, examined...



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