Sunday, 30 May 2010

Important New Ordovician Beasties

I'm a bit late in mentioning this particular discovery, but it is worth mentioning nonetheless. Palaeontologists in Morocco have discovered some assemblages of exceptional preservation from the early Ordovician period which are filling in the gaps in our knowledge of early metazoan evolution (I'm using early quite broadly there). Many Cambrian forms seem to come to an abrupt halt leaving no descendants in the Ordovician, giving rise to the view that the Cambrian was a time of evolutionary experimentation resulting in many dead ends and potentially quite a substantial extinction. The new soft body faunas of Morocco have thrown this view out of the window as they demonstrate that the change seen in the fossil record was due to absence in preservation; the organisms were there but not soft-bodies were found preserved, until now.

Halkieriids are among the forms now found to have lived in the Ordovician. Not only were Cambrian forms found to have continued until at least the Ordovician, but many groups have also had their earliest appearances pushed back. Horseshoe crabs are now known to be at least 30 million years older in the fossil record and cheloniellids (distant relatives of crustaceans and insects) make their first appearance in the Moroccan localities.

The above image, taken from the paper found here, shows some of the spectacularly preserved fossils. a) and b) are demosponges, c) is an annelid worm, d) shows similarity to halkieriids, e) is possibly an armoured lobopod (I do rather like those...) f) is a Thelxiope like arthropod, g) is a marrelomorph arthropod, h) a skaniid arthropod, and i) is a spinose arthropod.

This haul of fossils also highlights the usefulness of amateur palaeontologists and fossil collectors to palaeontology. Locals with interest in fossils are a great source of information as they often know the area better than anyone. Without the help of a local collector these Moroccan fossils may never have been found.

Morocco is quite an interesting place for fossil collectors. Entire fossiliferous areas are off limits, unless you enjoy getting shot at. Yet it is also one of the sources of fossils found in fossil shops worldwide. Be careful if you collect a Moroccan fossil though, it is also known for producing a large amount of fake fossils, I've seen a fake trilobite from there before and they are quite good at crafting fraudulent fossils. If in doubt, just take a freshly lit match (extinguished off course) and poke your fossil with it. If it melts then obviously you have got your hands on a lovely fake fossil probably made of resin. If your fossil is legit then your little experiment will do no harm to the fossil and you can sit happily knowing you have a genuine piece of Moroccan history.

No comments: