Mind the gap

The start of the Carboniferous, about 360 million years ago, was an important evolutionary period. In the oceans, there were some bizarre sharks, including the shop's logo, Akmonistion. Huge rhizodonts swam the rivers and eurypterids were in their prime. On land, though, things seem to be relatively quiet.

Amphibians were established but reptiles had yet to show up, and it's the development of the tetrapods that's so important. There isn't much fossil material thrown up by this period. In fact, there's so little that the first fifteen million years of the Carboniferous, from 360mya to 345mya, have a name - Romer's Gap. Alfred Romer, an American palaeontologist, first described this puzzling gap in the fossil record, wondering if there was particular reason or set of circumstances behind the missing information. Geochemical analysis of the rocks of that time suggest the lack of fossils may be the result of a period of low atmospheric oxygen, which would not promote the development of terrestrial animals, but the hangover of an extinction event usually needs more than a couple of aspirin to shake off, too.

Stan Wood has already contributed hugely significant finds from the East Kirkton quarry to help fill the gap, in Westlothiana and others, but tomorrow sees the opening of an exhibition of his recent finds which may shed some more light on the gap. The material will go on public display tomorrow at the National Museum on Chambers Street and the associated scientific paper will be published in the Proceedings of the National Academy of Sciences. Stan looks to have come up with the goods once again.