Writhlington revisited: A polychrome perspective (Part 3)

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Biddy Jarzembowski, Chris Proctor and Ed Jarzembowski (UK)

In this concluding part of the mini-series, we show the archaic wet forest at Writhlington (Fig. 9) which is the most familiar palaeohabitat associated with the Carboniferous age of coal. In the absence of flowering plants, the forest was less biodiverse than today’s tropical forest and more varied along the river banks (Fig. 5 in Part 2) than in the swamp. We also look in on the denizens of a forest pool (Fig. 10) and restore an extinct giant millipede (Fig. 11), one of the largest arthropods that ever lived, represented by tracks and body fossils there. An archaeorthopteran insect was seen at a distance in Part 1 (Fig. 3) and a brand-new image of another, but close up, is presented here (Fig. 12).

The fossiliferous rock tipped at Writhlington represents only a fraction of Carboniferous time, much more being locked up in the mass of peat that turned into coal. The latter went mainly to fire Portishead Power Station in North Somerset and would have included peatland palaeohabitats not reconstructed here. It is the ancient fresh-water floodplain (making up the miner’s ‘roof shale’) that has been explored in detail so far.

More information can be found in:
Jarzembowski, E. A. 2004. Atlas of animals from the Late Westphalian of Writhlington, United Kingdom. Geologica Balcanica, 34: 47-50, pls 1-2.  
Jarzembowski, E. A. 2018. Writhlington Geological Nature Reserve. In Geological sites of the Bristol Region. BRERC, Bristol.
Proctor, C. J. and Jarzembowski, E. A. 1999. Habitat reconstructions in the late Westphalian of southern England. Proceedings of the 1st International Congress of Palaeoentomology, Moscow, 1998: 125-129.
Fig. 9. The flooded forest with gathering mist, dominated by the scale tree Lepidodendron aculeatum Sternberg, with some seed-fern understory of Laveineopteris rarinervis (Bunbury). Compare this view with the dry forest and litter community in Part I (Figs. 1 and 4).
Fig. 10. A peaty pool, sometimes a sluggish stream, in the forest, with waterlogged scale-tree leaves on the bottom, on which is walking an extinct, fresh-water horseshoe crab, Euproops danae (Meek & Worthen). The light-coloured shells are fresh-water bivalves resembling the extinct species Anthraconaia saravana (Schmidt). The darker, smaller ‘shells’ are the carapaces of extinct clam shrimps, belonging to the species Anomalonema reumauxi (Pruvost). Tracks and body fossils have been reunited in this view, and the leaves are the same as in Fig. 4 (in Part 1).
Fig. 11. A millipede-like arthropod, Arthropleura armata Meyer, which grew to some two metres long following ‘Cope’s rule’ (that is, some animal groups tend to increase in body size over evolutionary time, named after American palaeontologist, Edward Drinker Cope).. The Writhlington tracks and body fossils, however, belong to relatively small individuals, two-thirds of a metre or less in length.
Fig. 12. An extinct archaeorthopteran, Gerarus danielsi Handlirsch, resting on a partly eaten pinnule of a neuropterid seed fern. This iconic Carboniferous insect is also known from complete bodies found in North America. It inspired the design of the silver gerarid award given by the International Palaeoentomological Society (IPS). The marginal feeding traces belong to the ichnospecies Phagophytichnus ekowskii van Amerom.


Our thanks to Fred Clouter (UK) and Alister Cruickshanks (UKGE) for help with imaging; and Felix Schwartz and fellow miners, who originally unearthed the fossiliferous rock at Writhlington.

Other articles in the series consist of:
Writhlington revisited: A polychrome perspective (Part 1)
Writhlington revisited: A polychrome perspective (Part 2)
Writhlington revisited: A polychrome perspective (Part 3)

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