Millipedes were first to shift to land
Modern millipedes like this take in oxygen the same way as their ancient ancestors did (Petroglyph National Monument)
Millipedes were the oldest creatures to leave the primordial soup and live permanently on land, according to U.S. and U.K. scientists.
Dr Heather Wilson from Yale University in Connecticut and Dr Lyall Anderson from the National Museums of Scotland in Edinburgh published their study of fossilised millipedes in the latest issue of the Journal of Paleontology.
Amateur fossil collector Mike Newman discovered the ancient remains at Cowie Harbour, south of Aberdeen in Scotland, so the millipede was named after him (Pneumodesmus newmani).
The millipede was 420 million years old, about 20 million years older than the daddy longlegs spider that previously held the record for the oldest life form to live on land.
The researchers looked at the ancient millipede's spiracles, holes that absorb oxygen directly from the air into the body, the same way millipedes do today. These spiracles were the oldest ever found, indicating this was the first creature known to have a respiratory system to allow it to breathe on land.
"It was obvious to me this was the oldest example of this group of animals that has ever been found," Anderson told the Scottish newspaper the Sunday Herald.
"The fact [the millipede] 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," he said.
Fossil discoverer Newman told the newspaper the site had recently been recorded as belonging to a more ancient geological period than was previously thought. The fossils are from the Silurian period, which began about 500 million years ago, a period that researchers say was associated with rapidly diversifying life forms.
Like other animals, millipedes evolved from ancient relatives that lived in the sea. They are often called living fossils as they have remained relatively unchanged over a long period of time.
Millipedes have evolved into more than 10,000 species, none of which have 1000 legs as their name suggests. They are not related to centipedes, which likewise, don't have 100 legs.
Millipedes are not insects but arthropods or members of the phylum Arthropoda, as are insects, spiders and crustaceans.
