Fossil spiders in Baltic amber

Anthonie Hellemond (Belgium) Spiders represent the most diverse group of obligate predators (that is, predators that feed solely on other animals) in terrestrial ecosystems today, with almost 48,000 extant species in 118 families described to date. The number increases annually by approximately 500 species as a result of new discoveries and it has been estimated that the true diversity may number around 160,000 extant species. This great diversity is no doubt at least in part due to their geological longevity, with the oldest known fossil spider dating back to the Carboniferous. In addition, spiders appear to have co-radiated along with their insect prey over geological time and they also appear to have been relatively resistant to extinction during the major events that eliminated many other terrestrial animal groups, such as the dinosaurs (Penney and Selden, 2011). Most people seem to presume that spiders do not have a very good fossil record on account of their very small size and their lack of a mineralised, bony skeleton. However, spiders actually have a very good fossil record, with 1,347 fossil species currently recognised. Fossil spiders occur in rocks of various different types, but the vast majority and best-preserved spiders are found as inclusions in amber from various localities dating back to the Cretaceous, although preservation tends to be better in the younger (for example, Miocene and Eocene) ambers. The best known of these deposits is Baltic amber, with more than 650 fossil spider species recognised (Penney et al., 2012), representing close to … Read More

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Florissant fossil spider discovery

Zachary J Sepulveda (USA) and Steven Wade Veatch (USA) The Florissant Fossil Beds National Monument is known worldwide for its late Eocene (34Ma) fossil plants and insects. Recently, a fossil spider was discovered at the commercial quarry, which is near the fossil beds (Fig. 1). Due to the condition of the fossil, it can only be assigned to the family Lycosidae (see table) (Rasnitsyn, 2012). If correct, this classification would make it a wolf spider. This fossil wolf spider lived 34Ma under Florissant rocks, within the forest litter or on short herbaceous plants (Meyer, 2003). Based on its modern relatives, it would have had colours that helped camouflage it, allowing it to hide from its prey (Meyer, 2003). According to the Florissant Fossil Beds National Monument fossil database, only one other member of the family Lycosidae (from the Greek word for ‘wolf’) has been discovered there. Petrunkevitch (1922) described this fossil and assigned it to the species Lycosa florissanti, from a well-preserved fossil specimen. Spiders belong to the class Arachnida. Unlike insects, arachnids have eight legs instead of six, have two body sections instead of three, and do not have antennae or wings. Taxonomy of wolf spider from the Florissant Fossil QuarryKingdom:AnimaliaPhylum:ArthropodaSubphylum:ChelicerataClass:ArachnidaOrder:AraneaeSuborder:LabidognathidaeFamily:LycosidaeThese spiders are incredibly successful – with a lineage stretching back millions of years. With over 100 genera and 2,300 species, they are capable predators spread throughout the entire globe and can inhabit almost every type of environment. From shrub lands to coastal forests, from gardens to alpine meadows, … Read More

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Fossil arachnids

Dr David Penney (UK) and Dr Jason Dunlop (Germany) When it comes to fossils, arachnids are not a group that obviously springs to mind. However, with more than 100,000 described living species, Arachnida form the second most diverse group of primarily land-living organisms after the insects. And they probably made up a significant proportion of the Earth’s biodiversity in the past, just as they do in terrestrial ecosystems today. Despite this, arachnids have usually received only a cursory mention in palaeontology textbooks. In fairness, they are not as common as trilobites or brachiopods in the fossil record, and are usually found only under conditions of exceptional preservation. Yet, despite their rarity, we aim to show here that there are more fossil arachnids out there than is sometimes appreciated. What are arachnids? Arachnids are not insects and can easily be differentiated from them by the fact that they have eight legs and, in general, two principal parts to the body. Arachnids also lack both wings and antennae. In total, there are 16 arachnid orders (including four extinct) and all of them have a fossil record. Despite the advent of computer cladistic analysis and new molecular techniques, the relationships between the different arachnid orders continues to be debated and there is no universally accepted consensus regarding how they are all related to one another. Fig 1. Basic body plans of the fossil and extant arachnid orders. Note that the eye arrangement in Uraraneida is unknown.Arachnids as fossils Fossil arachnids date back more … Read More

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Rare amber inclusion of harvestman donated to Natural History Museum, London

Terence Collingwood (UK) Recently, I was lucky enough to unearth a prize find – a 40-million-year-old, spider-like insect perfectly preserved in amber. I found the valuable harvestman in a piece of prehistoric amber and considered it to be of such scientific interest that I donated it to the National History Museum in London. Fig. 1. Piece of Baltic Amber, slightly larger than a £2 coin. Amber is the name for fossil tree resin, which is appreciated for its colour and beauty and used for the manufacture of ornamental objects and jewellery. Although not mineralised, it is sometimes considered to be a gemstone. It can also act as nature’s time capsule, telling us about life in ancient forests. This is because, millions of years ago, the original resin was once a gluey trap, which captured small insects as it oozed from tree bark. Therefore, it is extremely important for understanding the history of prehistoric land-living animals, particularly small insects that are not often preserved in rocks. I have been buying, collecting and selling fossils for several years and, more recently, for my shop I Dig Dinos in Rochester High Street. I consider every piece of amber a chance to examine a past ecosystem and an opportunity to gain insight into an extinct age. Therefore, each piece of amber I buy is examined and labelled meticulously and, every now and then, I find something a little different, rare or unusual. (I even make jewellery, bracelets, earrings, cufflinks and charms from this versatile … Read More

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