Wealden insects: An artist’s impression (Part 1)

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Biddy Jarzembowski, Neil Watson and Ed Jarzembowski (UK)

Fossil arthropods carry their skeletons on the outsides of their bodies. These exoskeletons may not only be preserved in the fossil record, but also the colour patterns that once adorned them. Therefore, the reconstruction and restoration of the appearance of fossil insects can sometimes be easier and more objective than that of animals that carry their hard parts on the insides of their bodies (such as dinosaurs).

In the 1990s, one of us (Neil) undertook the first artistic impressions in pencil and ink of newly-discovered Wealden insect remains from the Early Cretaceous of southern England. A selection of these subsequently appeared in newsletters, books and journals as black-and-white drawings of the whole animal in a life-like pose. Four-colour reproduction is now so widespread, as in this magazine, and more intact fossils have been found, especially in China, that a colour update was needed.

However, in this age of computer graphics, Biddy has only used a paint brush and water colours to tint Neil’s images, preserving the original hand-drawn style, and only resorting to Paint software where anatomical details needed changing in the light of new knowledge. Full colour also brought new challenges: decisions had to be made on hues as well as shades. Therefore, Ed has composed some explanatory notes to accompany the pictures. We hope that the first half-dozen results are less artistic licence and more visual models of these ancient life forms. You are, of course, the judge.

Fig. 1. Long-horn grasshopper or bush cricket of the extinct genus Panorpidium in the extinct family Elcanidae with characteristic prominent spines on the hindlegs. This is the oldest ‘Wealden’ insect reconstructed — actually inspired by the species Panorpidium tessellatum Westwood from what is now the Purbeck Limestone Group, but once included in the Wealden. This species appears to have a camouflaged wing pattern (in contrast to Panorpidium bimaculatum Gorochov, Jarzembowski and Coram with eyespots — see Kalligramma below ― from the younger Weald Clay). The fossil was found in a lagoonal palaeoenvironment, so the body colour is based on modern Metrioptera, which lives on marshand bog vegetation.
Fig. 2. Caddisfly larva and pupa of the extinct ichnogenus, Conchindusia, from the Hastings Group (which succeeds the Purbeck Limestone Group). Known only from trace fossils (caddis cases), the larva of the common species, Conchindusia rasnitsyni Jarzembowski, in the Ashdown Formation still remains to be discovered unlike in the picture. Nevertheless, the cases encrusted with clam-shrimp valves are coloured as in live footage of these animals on ‘U Tube’, and are not the familiar dark brown of fossils.  The pupa is depicted attached to a horsetail stem as Equisetites is also common in the Ashdown Formation.
Fig. 3. Lacewing of the extinct genus, Kalligramma, placed in its own extinct family, Kalligrammatidae, also from the Hastings Group. Like other species in this family, Kalligramma crowsoni Jarzembowski from the Wadhurst Clay Formation reconstructed here has eyespots to frighten vertebrate predators, like some modern butterflies. Exceptionally-preserved fossil finds from China, Myanmar (Burma) and Russia show that kalligrammatids had beak-like mouthparts for probing plants, unlike modern lacewings, which have predatory jaws. The reconstruction has been adjusted accordingly.
Fig. 4. Flying termites of the reproductive caste belonging to the extinct genus and species, Valditermes brenanae Jarzembowski from the Weald Clay (which succeeds the Hastings Group). These early social insects would have infested wood rather than constructed earthen mounds as suggested by some reconstructions of the Wessex Formation in the Isle of Wight. Therefore, the bodies are based on modern Termposis, as only the wings from nuptial flights have been found so far.
Fig. 6. Archaic beetle of the ‘form’ genus Zygadenia belonging to an extinct tribe, Notocupedini, also from the Weald Clay. This species, Zygadenia simpsoni Jarzembowski, Wang, Zhang and Fang was originally thought to resemble the relict modern beetle, Cupes, but is now considered to be more like another rare relict beetle, Omma. The body has been adjusted accordingly in this restoration, although the distinctive pattern on the wing cases of this species remains the same.
Fig. 7. Scorpionfly of the extinct genus, Mesopanorpa, in the extinct family Orthophlebiidae, again from the Weald Clay. This species (in the process of being described), with characteristic brown-mottled wings, as in modern Panorpa, is depicted as eyeing up a potential meal (dead Wealden pill beetle) on the ground. It has the upturned male genitals, which resemble scorpion stings in modern species, and this is confirmed by fossils from China.

Further reading

English Wealden fossils, Palaeontological Association Field Guide to Fossils No 14, edited by David J Batten, The Palaeontological Association, London (2011), 769 pages (Paperback), ISBN: 978-14-44367-11-9

Other articles in this series comprise:
Wealden insects: An artist’s impression (Part 1)
Wealden insects: An artist’s impression (Part 2)
Wealden insects: An artist’s impression (Part 3)
Wealden insects: An artist’s update (Part 4)

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