Picture yourself strolling through lush, green woodland, on an Earth unspoiled by man and yet to witness the rise of the dinosaurs. You’d be forgiven for feeling at peace with the world, even slightly euphoric – that is until you stumbled across the giant Arthropleura, a millipede relation as long as a park bench. This encounter might make even the most enthusiastic creepy-crawly hater think twice before squashing the bug in front of them under foot!
I (JS) had a slightly less dramatic (but still very exciting) experience involving the creature while on a recent fossil hunting trip to Crail in Fife. On investigating some sandstone ledges that ran across the shore to the south-west of this pretty little fishing village in western Scotland, my eyes were drawn to what could only be a huge set of fossil tracks in the rock. The stratum in which they had been preserved also contained plant remains such as Stigmaria roots, as well as sections of tree trunks and branches.
I took numerous photographs of the track, which measured about 3m long by 30cm wide and also of other, similar tracks nearby, in the hope that someone might be able to identify what kind of creature had created them. My guess was that it was some sort of amphibian, but I wasn’t sure. All I knew was the thing that made them was BIG.
Happily, when I posted a picture on the UK Fossils Discussion Board, (www.discussfossils.com), the tracks were quickly identified by Fiona Jennings and Steve Day as being some quite well-known examples belonging to Arthropleura. Given the interest shown in these on the forum, Steve suggested that we might co-write an article on this ancient giant for Deposits magazine.
Geological and geographical range
Arthropleura predominantly lived in the ‘coal swamp’ biome, across the Euramerican minor supercontinent of the Carboniferous period. The creature first appeared during the Namurian age of the first half of this geological period and is thought to have died out some time in the Stephanian at the end of the period. Significant body and trace fossils have been found in Britain, France, Germany, Holland, the United States and Canada. Although around ten different species of Arthropleura have been described from the Upper Carboniferous of Europe, the classification of the Arthropleurids is still very much an open debate at the subphylum and class levels.
The most abundant finds of Arthropleura have been made within the Saar River basin, with the best, most complete body fossil of the creature being found by Guthörl in 1934 in a coal mine near Saarbrüchen. Recently, further fine German specimens have been found near Chemnitz and Piesberg.
Trace fossils (including the tracks encountered by JS in summer 2007) show that the creature also roamed the area that is now Fife in Scotland, with tracks occurring between Boarhills and St. Monans, near St. Andrews. The geology of this stretch of coast belongs to the Anstruther Beds that form part of the Dinantian Strathclyde Group. There are a variety of rock types within this group including thin coals, lagoonal mudstones and laminated siltstones and shales.
Tracks also occur in the Tynemouth Creek Formation of Gardner Creek Bridge, on the outskirts of New Brunswick in Nova Scotia, Canada. The formation sequence containing these trace fossils consists of red sandstones, interbedded with red and green siltstones. American examples have been reported from numerous states including Illinois, Ohio, Pennsylvania and New Mexico.