Writhlington revisited: A polychrome perspective (Part 1)
Biddy Jarzembowski, Chris Proctor and Ed Jarzembowski (UK)
Thanks to ‘King Coal’, it is perhaps all too easy to visualise the Carboniferous Period – and especially the Pennsylvanian Subperiod – in black and white or shades of grey. The Earth’s first tropical forests – which gave us peat which turned to coal – were, however, perhaps no less colourful than some modern forests. The long-term project at Writhlington, near Radstock, currently in Bath and North East Somerset (UK), has produced a rich fossil record from the Farrington Formation dating back some 308myrs BP (to the late Asturian (Westphalian D) subage or late Moscovian). Not only has it produced many specimens, but has also allowed meaningful correlation between fossil assemblages and rock types (lithologies) left discarded on the waste tip (batch) of the former Lower Writhlington Colliery. (The finds at Writhlington can be explored by a list of further reading, which will be given in Part 3.)
In the closing years of the last century, one of us (Chris) produced several reconstructions in traditional black and white, which illustrated several learned papers and regional museum displays. These included the palaeohabitat as well as selected species. Here, Biddy has applied paint brush and water colours for the first time to these scientific restorations for a new audience – tantalisingly, due to the remoteness of the age of coal. Ed has composed some explanatory notes to accompany the pictures in this three-part mini-series.
This year marks the fortieth anniversary of the RJG Savage guide to the geology of the Bristol district, which includes Radstock (Geological Excursions in the Bristol District). A fresh book is in preparation by BRERC (Bristol Regional and Environmental Record Centre). Times change, mines close, yet the fossils continue to inspire us.
Fig. 1. The Late Carboniferous forests were dominated by extinct, tree-size clubmosses (lycopsids or lycophytes; scale trees) unlike modern forests. The dominant tree here at Writhlington (growing to some 30m high) is the species Lepidodendron aculeatum Sternberg. Occasional extinct seed ferns (pteridosperms) are represented by Laveineopteris rarinervis (Bunbury) in the top left corner. Such forests are often restored as being wet (resembling the Florida Everglades), but a temporary dry or marginal area is shown here.
Fig. 2. When the water level rose in the forest, the terrestrial arthropods no doubt shinned up the trees. A rare whipspider (or whipscorpion) found at Writhlington, possibly belonging to the extinct species Protophrynus carbonarius Petrunkevitch, is shown here resting on the bark of a scale tree displaying old leaf scars on the upper part of the trunk. (The scars are absent on the lower part.)
Fig. 3. An extinct blattinopsidaean insect, Westphaloblattinopsis edwardsae Béthoux & Jarzembowski, resting perched on a twig of L. aculeatum. Flying towards it is an extinct archaeorthopteran insect with disruptive markings, Narkeminopsis eddi Whalley, found on the tip (batch) of nearby Kilmersdon Colliery, which joined Writhlington Colliery prior to closure.
Fig. 4. At Writhlington, the fossil insects and arachnids are often associated with the foliage of L. aculeatum and are here shown scuttling around on the forest litter. Unlike the animals, different parts of the tree have different names. Therefore, the grass-like leaves are called Cyperites, the flag-like leaves Lepidostrobophyllum, a cone fragment is Lepidostrobus, with only the twigs being referred to as Lepidodendron. The insects are cockroaches (or cockroachoids) belonging to species of the extinct genera,Archimylacris (left) and Sooblatta (right). The insect with the short wings is an immature nymph. The predatory arachnids are an armoured spider (Pleophrynus verrucosa (Pocock) black, left) and an extinct architarbid (Bornatarbus mayasii (Haupt) brown, right).
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