F Rosa Rubicondior: Creationism in Crisis - A Spiny-Legged Arachnid From Over 300 Million Years Before 'Creation Week' - Giving Creationists Nightmares

Saturday 18 May 2024

Creationism in Crisis - A Spiny-Legged Arachnid From Over 300 Million Years Before 'Creation Week' - Giving Creationists Nightmares

Reconstruction of the 308-million-year-old arachnid Douglassarachne acanthopoda from the famous Mazon Creek locality.
Credit: Paul Selden
Ancient arachnid from coal forests of America stands out for its spiny legs | KU News

The technical term for the fear of learning that creationists seem to suffer from, is 'sophophobia' (from the Greek for knowledge or wisdom (sophia) and fear (phobia)). Their other manifest fears are 'atelophobia' (literally, a fear of being wrong) and theophobia (fear of gods).

Combine those acute anxiety disorders with arachnophobia (fear of arachnids or more precisely spiders) and sesquipedalophobia (fear of long words) and you can begin to understand why creationists can never be induced to read science papers like this one, which describes a fossilised arachnid with heavily-armoured, spiky legs from about 308 million years ago, that scientists have named Douglassarachne acanthopoda.

If anything is designed to deter creationists from reading about it, it is a fearsome arachnid with a long name that would make any creationists imaginary 'friend' really angry if they learned about it and might even make them wonder if they could be wrong. What could be more terrifying for a creationist?

So, creationists should either stop reading now, or find a responsible adult to be with them, because this describes how and where this 308 million-year-old fossil was found and how it fits in with what we know of the evolution of the arachnids, which includes spiders, mites, harvestmen, tics and the sister group, scorpions.

The fossil was found in shale in a coalmine spoil tip at Mazon Creek, Illinois, USA by palaeontologists Paul Selden from the University of Kansas and the Natural History Museum of London and Jason Dunlop from the Museum für Naturkunde Berlin. They have written up their discovery in an open access paper in the Journal of Palaeontology and describe it in a University of Kansas news release:

Ancient arachnid from coal forests of America stands out for its spiny legs

More than 300 million years ago, all sorts of arachnids crawled around the Carboniferous coal forests of North America and Europe. These included familiar ones we’d recognize, such as spiders, harvestmen and scorpions — as well exotic animals that now occur in warmer regions like whip spiders and whip scorpions. But there were also quite bizarre arachnids in these habitats belonging to now extinct groups. Even among these stranger species now lost to time, one might have stood out for its up-armored legs. The ancient critter recently was described in a new paper published in the Journal of Paleontology, co-written by Paul Selden from the University of Kansas and the Natural History Museum of London and Jason Dunlop from the Museum für Naturkunde Berlin.

Douglassarachne acanthopoda comes from the famous Mazon Creek locality in Illinois and is about 308 million years old. This compact arachnid had a body length of about 1.5 centimeters and is characterized by its remarkably robust and spiny legs — such that it is quite unlike any other arachnid known, living or extinct.

Professor Paul A. Selden, lead author.
Gulf-Hedberg Distinguished Professor Emeritus
Department of Geology
University of Kansas, Lawrence, Kansas, USA
The KU researcher said Carboniferous Coal Measures are an important source of information for fossil arachnids, representing the first time in Earth’s history when most living groups of arachnids occurred together. Yet, the fauna was still quite different to today.

Spiders were a rather rare group, only known at that time from primitive lineages, and they shared these ecosystems with various arachnids which have long since died out. Douglassarachne acanthopoda is a particularly impressive example of one of these extinct forms. The fossil’s very spiny legs are reminiscent of some modern harvestmen, but its body plan is quite different from a harvestman or any other known arachnid group.

Jason A Dunlop, co-author
Museum für Naturkunde,
Leibniz Institute for Evolution and Biodiversity Science
Invalidenstraße, Berlin, Germany.
This led the two scientists to conclude it doesn’t belong in any of the known arachnid orders.

Unfortunately, details such as the mouth parts cannot be seen, which makes it difficult to say exactly which group of arachnids are its closest relatives. It could belong to a wider group, which includes spiders, whip spiders and whip scorpions. Whatever its evolutionary affinities, these spiny arachnids appear to come from a time when arachnids were experimenting with a range of different body plans. Some of these later became extinct, perhaps during the so-called ‘Carboniferous Rainforest Collapse,’ a time shortly after the age of Mazon Creek when the coal forests began to fragment and die off. Or perhaps these strange arachnids clung on until the end Permian mass extinction?

Professor Paul A. Seden.
According to the team, Mazon Creek fossil locality is one of the most important windows into life in the late Carboniferous, producing a wide range of fascinating plants and animals. The present fossil was discovered in a clay-ironstone concretion in the 1980s by Bob Masek and later acquired by the David and Sandra Douglass Collection and displayed in their Prehistoric Life Museum.

The genus name Douglassarachne acknowledges the Douglass family, who kindly donated the specimen to the Field Museum of Natural History in Chicago for scientific study once it became apparent that it represented an undescribed species. Then, acanthopoda refers to the unique and characteristic spiny legs of the animal.

Jason A. Dunlop.

A new genus and species of arachnid (Chelicerata: Arachnida), Douglassarachne acanthopoda n. gen. n. sp., is described from the late Carboniferous (Moscovian) Coal Measures of the Mazon Creek Lagerstätte, Illinois, USA. This is a unique animal with distinctive large spines on the legs. It has a subovate body, a segmented opisthosoma, and a terminal anal tubercle. The legs are robust and appear to have been similar in construction throughout the limb series, with heavy spination of the preserved proximal podomeres. The mouthparts and coxo-sternal region are equivocal. The preserved character combination does not permit easy referral to any known arachnid order, living or extinct, thus the new fossil in placed as Arachnida/Pantetrapulmonata incertae sedis. It contributes to an emerging pattern of disparate body plans among late Carboniferous arachnids, ranging from anatomically modern members of living orders through to extinct taxa, such as the present fossil, whose phylogenetic position remains unresolved.

UUID: http://zoobank.org/b70f5f95-9c8b-4389-bee5-b6031bff2ee2

Non-technical Summary
The forests of the late Carboniferous period (about 300–320 million years ago) harbored a great variety of arachnids. In addition to the familiar spiders, harvestmen, and scorpions, there were other, stranger kinds of spider-like animals. Here, we describe a large spider-like arachnid with very spiny legs (presumably to deter predators), from the world-famous Mazon Creek fossil localities of Illinois, USA.

The late Carboniferous Coal Measures of North America and Europe offer an important window into the early evolution and diversity of arachnids. As well as hosting groups that are known from older deposits, namely scorpions (Scorpiones) and harvestmen (Opiliones), which have Silurian and Devonian representatives, respectively, the Coal Measures also yield the oldest records of several arachnid orders, namely spiders (Araneae), whip spiders (Amblypygi), whip scorpions (Thelyphonida), tick spiders (Ricinulei), and camel spiders (Solifugae) (for a recent overview of oldest records see Garwood and Dunlop 2023a, table 1). In addition to living arachnid groups, the Coal Measures also host three extinct orders: Trigonotarbida (known from the Silurian to the Permian), Phalangiotarbida (Devonian–Permian), and the monotypic Haptopoda (Carboniferous). What is also becoming apparent (e.g., Garwood et al. 2016; Selden 2021) is that there are several Coal Measures fossils of ostensibly spider-like animals that were sometimes initially placed in Araneae, but which lack the key character of silk-producing spinnerets. The impression is that several arachnid fossils of this age belonged to extinct lineages whose position in relation to the established orders has yet to be resolved.

The Mazon Creek Fossil-Lagerstätte is rightly famous for the abundance of marine and non-marine fossil biota found in clay ironstone concretions that are collected from the spoil heaps of the old strip mines around Braidwood in northeastern Illinois (Selden and Nudds 2012) (Fig. 1.1, 1.2). These localities have yielded fossils of all the extant and extinct arachnid orders listed above (e.g., Meek and Worthen 1868; Scudder 1868.1, 1884, 1890; Melander 1903; Petrunkevitch 1913, 1945; Selden 1992), with the exception of Haptopoda, which has only been found in the British middle Coal Measures. The new fossil from Mazon Creek is evidently something very different from any previously described arachnid from either this or any other Coal Measures locality. It is characterized by its distinctive habitus of an ovate body and robust and very spiny legs. The preserved character combination makes it difficult to place the fossil in any known arachnid order (see below), but it is described and named here with comments on its possible affinities.
Figure 1. Type locality and stratigraphy for Douglassarachne acanthopoda n. gen. n. sp. (1) Locations of strip mines and dumps from shafts in the Mazon Creek area; Pit 15 Northern Mine shown in bold at bottom right; (2) map showing the location of (1) in Illinois; (3) stratigraphic log of the Francis Creek Shale Member and associated members of the Carbondale Formation, with position of concretions in lower part of Francis Creek Shale Member emphasized in bold (map and log based on Baird et al.1986).
Geological setting
The specimen was found at the spoil heap of Pit 15 Northern Mine near Essex, Kankakee County, Illinois, coordinates: 41.1525°N, 88.2275°W (Fig. 1). The fossil-bearing concretions occur in the Francis Creek Shale Member of the Carbondale Formation, which overlies the Colchester No. 2 Coal Member, and is itself overlain by the Mecca Quarry Shale Member (Selden and Nudds 2012; Clements et al. 2019); the concretions are generally found towards the base of the Francis Creek Shale Member (Fig. 1.3). Based on the Mazon Creek flora containing elements comparable to those in the late Asturian Substage of Western Europe, and the dating of ash beds associated with cyclothems in Europe and North America (Montañez et al. 2016.1), the age of the coal and overlying shale member of the Mazon Creek area is now established to be between 308.6 and 308.4 million years old.
Figure 2. Douglassarachne acanthopoda n. gen. n. sp., holotype and only known specimen FMNH PE 91366. (1) Photograph of part; (2) explanatory drawing of part; (3) photograph of counterpart; (4) explanatory drawing of counterpart; 1–4 = leg numbers; a t = anal tubercle; e t = eye tubercle; fe = femur; t = tergite. Scale bars = 5 mm.
Figure 3. Douglassarachne acanthopoda n. gen. n. sp., holotype and only known specimen FMNH PE 91366; for interpretative drawings and scale, see Figure 2. (1) Part, detail of distal femur and more-distal podomeres, showing nature of curved macrospines on lateral edge of distal podomeres, bases of macrospines on dorsal surface of femur; (2) counterpart, detail of posterior opisthosoma showing bilobed structure at base of anal tubercle.

Imagine being raised by fundamentalist, creationists parents who will have taught you that a magic mind-reading thug in the sky, who has an especially nasty punishment for you if you have the wrong thoughts, and that you mustn't learn anything that might make you doubt the literal truth of the Bible, and because of your limited, creationist education, you probably wouldn't understand it anyway, it's easy to understand why creationism results in such ignorance of science and even depends on it, and why parents and creationist cult leaders actively discourage learning.

But ignorance doesn't create truth, of course, and the facts are still there whether creationists know and understand them or not. So, when creationists do manage to overcome those psychological barriers; those irrational phobias that are designed to keep them ignorance, they are free to discover a fascinating and infinitely interesting world, not just in the present, but in the history and historical forces that shaped the present, and the who suddenly become much richer and rewarding that ever the Bronze Age authors of the Bible ever thought.

It is an enduring mystery why people who believe a god created the entirely of reality are so reluctant to discover it, in case that same god gets angry with them for learning about it.


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