Arthropleura fossil embedded in sandstone
© Neil S. Davis
An old story from December 2021, which I somehow missed, is currently being given another airing in the social media, so I'll take this opportunity to make up for my earlier oversight. It is the news that the largest known ancient arthropod was discovered on a Northumberland, UK, beach.
It is interesting not so much because it refuted creationism by living 326 million years before the Universe existed according to creationism, but because it could only have reached that size by living in a high-oxygen environment such as pertained in the Carboniferous Era.
The basic problem with all the arthropods is that they depend on passive diffusion to exchange gasses (oxygen (\(\small \ce{O2})\) and carbon dioxide (\(\small \ce{CO2})\)) with their environment via series of spiracles, so the rate of diffusion is proportional to the concentration of \(\small \ce{O2}\) and \(\small \ce{CO2}\) in the atmosphere. The millipedes partly overcome this limitation by being long and thin.
Tell me all about the giant arthropod, Arthropleura, please. Arthropleura was a fascinating and enormous prehistoric arthropod that lived during the Carboniferous Period, approximately 315 to 299 million years ago. It is one of the largest-known land-dwelling invertebrates ever to have existed, and it is often compared to modern-day millipedes due to its segmented, elongated body.The fossil was discovered in January 2018, in a large block of sandstone that had fallen from the cliff in Howick Bay in Northumberland. Fortunately the block split open in such a way as to perfectly expose the fossil, where it was spotted by a formed PhD student.
Physical Description
Arthropleura was a colossal creature, with some estimates suggesting it could reach lengths of up to 2.5 meters (about 8 feet) or more. Its body was composed of numerous jointed segments, each covered by a pair of armor-like plates called tergites. These segments gave Arthropleura a ribbed appearance and allowed it to move with surprising agility for its size. Unlike modern millipedes, which have numerous legs on each segment, Arthropleura's limbs were relatively small compared to its overall body size, though they were still numerous.
The exoskeleton of Arthropleura was likely made of chitin, a tough, protective material found in the exoskeletons of all arthropods. This exoskeleton provided protection from predators and may have played a role in retaining moisture, which would have been important for surviving in the terrestrial environments of the Carboniferous Period.
Habitat and Lifestyle
Arthropleura thrived in the lush, swampy forests that were prevalent during the Carboniferous Period. These forests were dominated by giant ferns, horsetails, and other primitive plants, which created a humid and oxygen-rich atmosphere. This high oxygen content in the Earth's atmosphere is believed to have been a key factor in allowing Arthropleura and other large arthropods to grow to such enormous sizes.
Arthropleura was likely an herbivore, feeding on the abundant plant material in its environment. Some evidence suggests it might have consumed decaying plant matter rather than live plants, making it more of a detritivore. Its large size would have allowed it to access a variety of food sources, from low-lying vegetation to fallen leaves and other organic debris.
Behavior and Movement
Despite its size, Arthropleura was likely a relatively fast-moving creature, capable of navigating through the dense undergrowth of its forested habitat. Its body structure suggests it moved in a serpentine or undulating manner, using its many legs to propel itself forward.
There is little direct evidence of Arthropleura's behavior, but its size and the structure of its exoskeleton suggest it had few natural predators. It may have relied on its size and the tough armor of its exoskeleton for defense, rather than speed or agility.
Extinction
Arthropleura went extinct at the end of the Carboniferous Period, around 299 million years ago. The reasons for its extinction are not entirely clear, but several factors may have contributed. The drying out of the Earth’s climate, the reduction in atmospheric oxygen levels, and the rise of new predators, such as early reptiles, could have all played a role in its decline.
Fossil Evidence
Fossils of Arthropleura are relatively rare, but they have been found in various parts of the world, including North America and Europe. These fossils usually consist of fragments of the exoskeleton, as the softer parts of the body did not fossilize well. However, trace fossils, such as footprints, have also been discovered, providing valuable information about how this giant arthropod moved and lived.
Significance
Arthropleura is significant not just because of its enormous size, but also because it represents a time when arthropods dominated the Earth’s ecosystems. Its existence during the Carboniferous Period is a testament to the unique environmental conditions of the time, particularly the high oxygen levels that allowed such giant invertebrates to thrive.
In summary, Arthropleura was an extraordinary giant millipede-like arthropod that lived in the Carboniferous forests. Its size, habitat, and extinction provide valuable insights into the evolutionary history of arthropods and the environmental changes that shaped life on Earth millions of years ago.
The fossil was painstakingly extracted from the block of sandstone and taken to Cambridge University's Department of Earth Sciences where it was examined by a team led by Neil S Davis. The team’s findings were published in the Journal of the Geological Society and announced in a Cambridge University news release in December, 2021:
Largest-ever fossil millipede found in Northern EnglandThe paper in the Journal of the Geological Society is still behind a paywall, so only the abstract is available:
The largest-ever fossil of a giant millipede – as big as a car – has been found on a beach in the north of England.
The fossil – the remains of a creature called Arthropleura – dates from the Carboniferous Period, about 326 million years ago, over 100 million years before the Age of Dinosaurs. The fossil reveals that Arthropleura was the largest-known invertebrate animal of all time, larger than the ancient sea scorpions that were the previous record holders.
The specimen, found on a Northumberland beach about 40 miles north of Newcastle, is made up of multiple articulated exoskeleton segments, broadly similar in form to modern millipedes. It is just the third such fossil ever found. It is also the oldest and largest: the segment is about 75 centimetres long, while the original creature is estimated to have measured around 2.7 metres long and weighed around 50 kilograms. The results are reported in the Journal of the Geological Society.
The fossil was discovered in January 2018 in a large block of sandstone that had fallen from a cliff to the beach at Howick Bay in Northumberland.
It was a complete fluke of a discovery. The way the boulder had fallen, it had cracked open and perfectly exposed the fossil, which one of our former PhD students happened to spot when walking by.
Neil S. Davies, First Author
Department of Earth Sciences
University of Cambridge, Cambridge, UK.
Unlike the cool and wet weather associated with the region today, Northumberland had a more tropical climate in the Carboniferous Period, when Great Britain lay near the Equator. Invertebrates and early amphibians lived off the scattered vegetation around a series of creeks and rivers. The specimen identified by the researchers was found in a fossilised river channel: it was likely a moulted segment of the Arthropleura’s exoskeleton that filled with sand, preserving it for hundreds of millions of years.
The fossil was extracted in May 2018 with permission from Natural England and the landowners, the Howick Estate.
It was an incredibly exciting find, but the fossil is so large it took four of us to carry it up the cliff face.
Finding these giant millipede fossils is rare, because once they died, their bodies tend to disarticulate, so it’s likely that the fossil is a moulted carapace that the animal shed as it grew. We have not yet found a fossilised head, so it’s difficult to know everything about them.
Neil S. Davies
The fossil was brought back to Cambridge so that it could be examined in detail. It was compared with all previous records and revealed new information about the animal’s habitat and evolution. The animal can be seen to have only existed in places that were once located at the Equator, such as Great Britain during the Carboniferous. Previous reconstructions have suggested that the animal lived in coal swamps, but this specimen showed Arthropleura preferred open woodland habitats near the coast.
There are only two other known Arthropleura fossils, both from Germany, and both much smaller than the new specimen. Although this is the largest Arthropleura fossil skeleton ever found, there is still much to learn about these creatures.
The great size of Arthropleura has previously been attributed to a peak in atmospheric oxygen during the late Carboniferous and Permian periods, but because the new fossil comes from rocks deposited before this peak, it shows that oxygen cannot be the only explanation.
The researchers believe that to get to such a large size, Arthropleura must have had a high-nutrient diet.
While we can’t know for sure what they ate, there were plenty of nutritious nuts and seeds available in the leaf litter at the time, and they may even have been predators that fed off other invertebrates and even small vertebrates such as amphibians
Neil S. Davies
Arthropleura animals crawled around Earth’s equatorial region for around 45 million years, before going extinct during the Permian period. The cause of their extinction is uncertain, but could be due to global warming that made the climate too dry for them to survive, or to the rise of reptiles, who out-competed them for food and soon dominated the same habitats.
The fossil will go on public display at Cambridge’s Sedgwick Museum in the New Year [2022].
Neil Davies is a Fellow of Churchill College, Cambridge. The research was supported in part by the Natural Environment Research Council.
AbstractIt is, of course, a characteristic of these sorts of finds that they are corroborated by and in turn corroborate several different strands of evidence. Such a large arthropod, given what we know of arthropod respiration, could only have evolved and lived at a time when there was a high level atmospheric \(\small \ce{O2}\) and a plentiful supply of nutrient material. This places it in the Carboniferous, in exactly the age of the rock formation in which it was found. This corroborates the theory that the Carboniferous would have been when large arthropods would have existed, given what we know of evolutionary biology.
Arthropleura is a genus of giant myriapods that ranged from the early Carboniferous to Early Permian, with some individuals attaining lengths >2 m. Although most of the known fossils of the genus are disarticulated and occur primarily in late Carboniferous (Pennsylvanian) strata, we report here partially articulated Arthropleura remains from the early Carboniferous Stainmore Formation (Serpukhovian; Pendleian) in the Northumberland Basin of northern England. This 76 × 36 cm specimen represents part of an exuvium and is notable because only two comparably articulated giant Arthropleura fossils are previously known. It represents one of the largest known arthropod fossils and the largest arthropleurid recovered to date, the earliest (Mississippian) body fossil evidence for gigantism in Arthropleura, and the first instance of a giant arthropleurid body fossil within the same regional sedimentary succession as the large arthropod trackway Diplichnites cuithensis. The remains represent 12–14 anterior Arthropleura tergites in the form of a partially sand-filled dorsal exoskeleton. The original organism is estimated to have been 55 cm in width and up to 2.63 m in length, weighing c. 50 kg. The specimen is preserved partially in three dimensions within fine sandstone and has been moderately deformed by synsedimentary tectonics. Despite imperfect preservation, the specimen corroborates the hypothesis that Arthropleura had a tough, sclerotized exoskeleton. Sedimentological evidence for a lower delta plain depositional environment supports the contention that Arthropleura preferentially occupied open woody habitats, rather than swampy environments, and that it shared such habitats with tetrapods. When viewed in the context of all the other global evidence for Arthropleura, the specimen contributes to a dataset that shows the genus had an equatorially restricted palaeogeographical range, achieved gigantism prior to late Paleozoic peaks in atmospheric oxygen, and was relatively unaffected by climatic events in the late Carboniferous, prior to its extinction in the early Permian.
Davies, Neil S.; Garwood, Russell J.; McMahon, William J.; Schneider, Joerg W.; Shillito, Anthony P. (2021).
The largest arthropod in Earth history: insights from newly discovered Arthropleura remains (Serpukhovian Stainmore Formation, Northumberland, England). Journal of the Geological Society 179(3) jgs2021-115; DOI: 10.1144/jgs2021-115
© 2021 Geological Society of London.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
Although creationists will try to present that as circular reasoning, it is in fact exactly what we would expect because real events involving several different geological, climatological and biological processes have a causal relationship so will always be mutually corroborative, just as the extinction of these organisms will also coincide with geological and climatological changes that caused them.
This is as obvious as the prediction that the formation of lakes and rivers in the Sahara would have been when the climate was wetter and rainfall was higher, and conversely that wetter weather and higher rainfall in the Sahara would have resulted in the formation of lakes and rivers. Not circular; merely corroboratory.
Sadly for creationists, there are no such independent strands of evidence corroborating any of their claims - either magic creation of species without ancestors a few thousand years ago or a global genocidal flood a few thousand years later. In fact, what evidence there is, such as this fossil, utterly refutes creationism, which continues to be not only an evidence-free superstition but an inherited superstition which runs counter to the available evidence.
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The mid to late Carboniferous period and early Permian period had oxygen levels higher than our modern 21 percent level. Arthropleura was monster sized but hopefully it was a herbivore and not venomous.
ReplyDeleteGiant Dragonflies also existed during this time period. This was the Age of Arthropods and Amphibians and the earliest Reptiles. This was still before the Dinosaurs appeared. Land plants became more abundant and were able to pump more oxygen in the atmosphere through photosynthesis. The majority of scientists agree that the Carboniferous period had breathable oxygen levels, greater than anything in the Devonian, or Silurian, or Ordovician, or Cambrian periods.
Creationists will continue to believe in a 6000 to 10,000 year old creation and an original perfect creation until the fateful day Adam and Eve ate a forbidden apple which then ruined the entire creation. Not so. There never was an original perfect creation, there never was a peaceable kingdom, there never was a paradise. The world was always the flawed, cruel, violent, dangerous place that's so familiar to us. Suffering, death, extinctions from predation, diseases, venoms, poisons, parasites, volcanic eruptions, intense cold, intense heat, meteor strikes and asteroid strikes have been raging for countless millions of years before Adam and Eve and before humans appeared on earth.