Rare fossil making scientists rethink

A fossil discovered on a beach has been confirmed as the earliest known creature to live on dry land.

The fossilised millipede, which is less than one centimetre long, was found a year ago on the shore at Cowie Harbour near Stonehaven, a fishing town just south of Aberdeen.

Scientists say it is about 420 million years old, some 20 million years older than what had previously been believed to be the oldest breathing animal -a spider-like creature chiselled out of the chert, a type of rock, at Rhynie, also Aberdeenshire. The millipede was discovered by an amateur fossil collector and has been named Pneumodesmus by palaeontologists at Yale University and researchers at the National Museums of Scotland, who have been studying the find.

The results have been published in the latest issue of the American Journal of Palaeontology.

Dr Lyall Anderson, curator of invertebrate palaeontology at the National Museums, said: ‘It was obvious to me this was the oldest example of this group of animals that has ever been found.’

The site near Stonehaven is well known in fossil collecting circles for its arthropods -such as sea scorpions.

However, those are all aquatic animals while the Pneumodesmus is air-breathing.

Dr Anderson continued: ‘The fact this has got very well developed structures to breathe air suggests there must have been things prior to that which these developed from, so we should be looking further back in time to see if this thing had ancestors.’

Dr Heather Wilson of Yale University, who also studied the Pneumodesmus, said: ‘There’s all sorts of other things we can expect to see: it’s unlikely we had an ecosystem with just plants and Pneumodesmus. There were probably a whole host of other terrestrial orthopods around at the same time. The special ecosystem was probably a lot more complex earlier than we had previously thought.’