425 Million-years-old Millipede Fossil Discovered In Scotland

425 Million-years-old Millipede Fossil Discovered In Scotland

A 425-million-year-old fossilized millipede has been discovered by researchers as the world’s oldest ‘bug’.

The remains were discovered on Kerrera, a Scottish island, and show that bugs and plants evolved much more quickly than previously thought.

After examining the petrified bug, the researchers discovered that ancient creatures left lakes 40 million years ago to live in complex forest ecosystems.

Researchers used a technique to determine that the millipede is 75 million years younger than previously estimated by extracting zircons, which is a microscopic mineral needed to accurately date the fossils.

Michael Brookfield, a research associate at the University of Texas Austin’s Jackson School of Geosciences and adjunct professor at the University of Massachusetts Boston, said: ‘It’s a big jump from these tiny guys to very complex forest communities, and in the scheme of things, it didn’t take that long.’

‘It seems to be a rapid radiation of evolution from these mountain valleys, down to the lowlands, and then worldwide after that.’

Brookfield, who led the study, worked with co-authors Elizabeth Catlos, a professor in the Jackson School’s Department of Geological Sciences, and Stephanie Suarez, a doctoral student at the University of Houston. Together they made improvements to the fossil dating technique used in the study.

Following the analysis, the team determined the fossilized millipede is 425 million years old, or about 75 million years younger than the age other scientists have estimated the oldest millipede to be using a technique known as molecular clock dating, which is based on DNA’s mutation rate.  

Although it’s certainly possible there are older fossils of both bugs and plants, Brookfield said that the fact they haven’t been found – even in deposits known for preserving delicate fossils from this era – could indicate that the ancient millipede and plant fossils that have already been discovered are the oldest specimens.

If this theory is true, then experts can determine that both bugs and plants evolved much more rapidly than the timeline indicated by the molecular clock.  Previous work has dated insect deposits to just 20 million years later than the fossils. 

And by 40 million years later, there’s evidence of thriving forest communities filled with spiders, insects and tall trees.

Given their potential evolutionary significance, Brookfield said that he was surprised that this study was the first to address the age of the ancient millipedes.

Suarez said a reason could be the difficulty of extracting zircons – a microscopic mineral needed to precisely date the fossils – from the ashy rock sediment in which the fossil was preserved. She improved the technique by separating the zircon grain from the sediment. 

Once zircons are released from the surrounding rock, the team was able to retrieve them with a pin glued to the tip of a pencil – a process the researchers said ‘involves an eagle-eye hunt.’

‘That kind of work trained me for the work that I do here in Houston,’ Suarez said. ‘It’s delicate work.’

She used the technique to find that a different millipede specimen, thought to be the oldest bug specimen at the time, was about 14 million years younger than estimated – a discovery that stripped it of the title of oldest bug.  Using the same technique, this study passes the distinction along to a new specimen.