Monday, 24 May 2010

Looking for shark fossils

Jenny has a PhD student, Kelly Richards, who started working on Carboniferous sharks last October. The specimens came from Derbyshire in about 2005 and are really quite interesting, though I think, hard work.

The key problem Kelly's trying to address is that most shark fossils from around the world are simply isolated teeth. There are very few fossils representing the actual bodies of these fish, because, of course, they have cartilaginous skeletons, which don't preserve well after death.

So you can compare the teeth with modern sharks' teeth and get some clues about the ecological niches occupied by the ancient ones, but it's all rather tenuous, if I've understood the whole argument correctly.

Our Derbyshire material has some skeletal remains associated with teeth, so Kelly's project is to identify what we've got, which should give us a much better idea of what the sharks were actually like. It's not quite as straightforward as that sounds, since the preserved cartilage is a squidgy black mess which often doesn't show up well when CT scanned, and is also very hard to prepare physically.

The first picture is of Kelly having just discovered a nice shark's tooth on the first day. The second is Jenny and Kelly in the first quarry we visited on the second day. It was shaping up to be hot! Last two photos are of the final quarry we visited on Saturday, one just the view and the other, Kelly, of course. Well, you know, old guys, young girls...

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