Wealden insects: An artist’s update (Part 4)

Biddy and Ed Jarzembowski (UK) An ‘artist’s impression’ of Wealden insects, inspired by the original work of Neil Watson, appeared in a three-part mini-series in Deposits issues 47 to 49. Since then, the discovery of a number of species new to science (belonging to diverse groups) has meant that an update was needed. Here are some completely new watercolours by Biddy, including the first true bug (heteropteran) from the Wealden, and the first Wealden earwig (dermapteran). Insects are arthropods and an accompanying Wealden crustacean is added this time. Photographs of actual fossils found in the Weald Clay Formation of Lower Cretaceous (Hauterivian and Barremian) age are provided too. We are indebted to Fred Clouter, Terry Keenan, Tony Mitchell and Pete Austen (UK) for help with these images. As before, Ed has supplied some explanatory notes to accompany the pictures, with more on the way. We have incorporated some new ideas on established species, such as different interpretations of the fossil lifestyle in the case of the ‘moss’ bug. Wealden insects are often disarticulated (due to transport in water). Where intact relatives are known from other contemporary deposits (especially Asia and Spain), these have been referred to, as well as recent representatives. While we can now recognise the commoner insect groups from the late age of the dinosaurs, continuing fieldwork shows that others remain to be unearthed. The artist’s job is ongoing, like that of the specialist and collector. We shall continue to periodically share the finds with you as a … Read More

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Boxstones: In search of Miocene Suffolk

Tim Holt-Wilson (UK) The date is 24 May 2014 and I am browsing across East Lane Beach at Bawdsey in southeast Suffolk. A brown lump of sandstone with a white fossil shell impression catches my eye. A boxstone. This is the first one I have ever found with a fossil in it. Looking closely, I see that the sea has abraded the shell’s outlines, although the margins have survived better than the rest, so it should be possible to identify the specimen (Fig. 1). Fig. 1. Boxstone, found 24 May 2014. Boxstones are fragments of a vanished world. They are all that remains of a lost geological stratum in Suffolk called the ‘Trimley Sands’ (Balson, 1990), although deposits of similar age are still present across the sea in Belgium and other parts of Europe. Boxstones are lumps or concretions of brown sandstone, which may contain shell fossils and – if you are extremely lucky – bones and teeth. They are beach-rolled and rounded, and typically measure between 5 and 15cm in diameter. The sand is mostly quartzose, with a rich assemblage of secondary minerals, and is cemented with carbonate-fluorapatite (a phosphate mineral) and calcite (Mathers and Smith, 2002). Boxstones can be found scattered sparsely across the shingle beaches at Bawdsey and Felixstowe Ferry (Fig. 2), and in situ as a common component of the basement beds (nodule beds) at the base of the Coralline Crag and Red Crag formations of southeast Suffolk (Fig. 3). They are eroding out of the … Read More

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Fossil crustaceans as parasites and hosts

Adiël Klompmaker (USA) Who would like to carry a parasite? I bet not many people would like to have one or more. They are nevertheless very common in humans and in other organisms, and can affect entire food webs including keystone species. They tend to be small compared to the host and the vast majority of them are soft-bodied. Despite their small size and soft appearance, they can affect the host substantially, for example, leading to a reduced growth rate and less offspring. Much of the same holds true for crustaceans – they are affected by parasites and can act as parasites themselves. For example, parasitic crustaceans are found among the isopods and copepods. Given the widespread occurrence of parasitism in and by crustaceans today, a fossil record of such parasitism may be expected. Swellings in fossil crabs and squat lobsters So what does the fossil record look like? I have been fortunate to have worked on this under-studied field of research. During my PhD research, I found various swellings in fossil crabs and squat lobsters (decapods from the superfamily Galatheoidea) during and after field work in northern Spain in reef carbonates from the mid-Cretaceous (upper Albian). They appeared to occur regularly in the back part of the carapaces of these crustaceans. Fig. 1. Bopyrid isopods from the species Orthione griffenis (large female and small male), removed from the right gill chamber of a modern mud shrimp (Upogebia pugettensis). (Photo by Stephen Ausmus, USDA Agricultural Research Service, http://www.bugwood.org.) This swelling … Read More

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Jamaican fossil crabs

Stephen K Donovan (The Netherlands) and Joe SH Collins (UK) Decapod crustaceans (crabs) are among the most attractive of fossils. Yet, the beautifully preserved specimens seen in museum displays and dealers’ catalogues are in stark contrast with the usual haul of the collector, that is, scraps, commonly claws or (more rarely) bits of carapace, which we all find in (mainly) Cretaceous and Cenozoic sedimentary rocks. However, these bits and pieces represent most of the fossil record of crabs and, as such, are of importance to the systematist and anyone with an interest in aspects such as taphonomy and palaeoecology. Just as it is possible to identify a shark from a tooth or a cidaroid echinoid from a spine, so a crab claw can commonly provide data that permits its identification to the level of genus or species (Collins, 1999). The present authors, in collaboration with Roger Portell of the Florida Museum of Natural History at the University of Florida in Gainesville, have been collecting and studying the fossil crabs of Jamaica (and the wider Antilles) for over 20 years. Until the 1990s, reports of fossil crabs from the island were limited to a few fragmented specimens and rare, well-preserved carapaces (some retaining claws) or the isolated claws of mud shrimps (=Callianassa sensu lato), which were collected mainly from the Upper Cretaceous and Eocene by visiting geologists as an aside to their own research. They were sent to the British Museum (Natural History) for description. These early records were reviewed and … Read More

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Geology and terrestrial life of the Carboniferous

Russell Garwood and Alan Spencer (UK) The Carboniferous Period is a fascinating time in earth history. It spanned 60Ma (359.2 to 299.0Ma), towards the end of the Palaeozoic era, falling between the Devonian and Permian. During the Carboniferous, the supercontinent Pangaea was assembling and the oceans were home to invertebrates such as corals, bryozoa, ammonoids, echinoderms, trilobites and crustaceans. Fish were also well represented (especially sharks), which were rapidly diversifying at the time. The continents were no barren wasteland either – they were host to some of the first widespread terrestrial forest and swamp ecosystems. In these lived both invertebrates, which had crawled onto land by the Silurian period (at least 423mya) and vertebrates, which were relative newcomers to this realm. This article provides us with an excuse to write about the Carboniferous. We will first introduce the geology and palaeogeography of the Carboniferous, including an overview of the most common mode of preservation we see in terrestrial fossils. Then, we will provide an overview of terrestrial life during the period, as land-based ecosystems of this age are among the best known from the Palaeozoic and an exciting time in the history of life. Fig. 1. Global paleogeographic reconstruction of the Earth in the late Carboniferous period 300mya. (C)opyright Dr Ron Blakey (Wikipedia Creative Commons). Carboniferous geology The Carboniferous is split into two epochs, the Mississippian (or Lower Carboniferous; 359.2 to 318.1mya) and the Pennsylvanian (or Upper Carboniferous; 318.1 to 299.0mya). As we shall see, the two are associated with … Read More

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Fossil crustaceans

Dr Neale Monks (UK) The crustaceans are the second biggest group of arthropods after the insects and have a good fossil record, but, for one reason or another, they are not as familiar to fossil collectors as the trilobites. It may be because they’re a bit harder to identify, with many of the most diverse groups being essentially microscopic, while the bigger ones like shrimps and crabs – arely get preserved in their entirety. But even if they’re difficult to identify, crustacean fossils are interesting and often make very attractive specimens. So that’s the theme of this article really – to draw your attention to these fossils and allow you to think a bit more deeply about what they were like and how t hey w ere all related to each other. Fig. 1. While most crustaceans are marine, a large number of crayfish live in freshwater, including crayfish. Crustacean origins The earliest crustaceans are known from Cambrian sediments including the well known Burgess Shale fauna. These primitive crustaceans are essentially worm-like in shape, but they do have many of the key features of crustaceans visible even on modern types such as shrimps. Their body is segmented, but the dorsal (back) part of each segmented was hardened into a thick, protective plate. Most segments bore a pair of appendages, one pair of legs and one pair of gills. This ‘biramous’ condition has been used to contrast the crustaceans (and also the trilobites) with the ‘uniramous’ insects and spiders that normally only … Read More

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