Arthropleuridea
{{Short description|Extinct subclass of millipedes}}
{{Automatic taxobox
| fossil_range = Late Silurian - Sakmarian {{fossil range|423|290}}
| image = Arthropleura 1914.jpg
| image_caption = Arthropleura fossil illustration
| taxon = Arthropleuridea
| authority = Waterlot, 1934
| subdivision_ranks = Orders
| subdivision =
}}
Arthropleuridea is an extinct subclass of myriapod arthropods that flourished during the Carboniferous period, having first arisen during the Silurian, and perishing in the Early Permian. Members are characterized by possessing diplosegement (fused "double segments", as in modern-day millipedes) paranotal tergal lobes separated from the body axis by a suture, and by sclerotized plates buttressing the leg insertions. Despite their unique features, recent phylogenetic research suggests Arthropleuridea be included among millipedes in the class Diplopoda.{{cite web | last = Kazlev | first = M. Alan | url = http://www.palaeos.com/Invertebrates/Arthropods/Arthropleurida/Arthropleurida.htm | title = Class? and Order Arthropleurida | work = Palaeos | accessdate = 2006-04-12 | archiveurl = https://web.archive.org/web/20060313173755/http://www.palaeos.com/Invertebrates/Arthropods/Arthropleurida/Arthropleurida.htm | archivedate = 13 March 2006 | url-status = dead }} The subclass contains three or two recognized orders, each with a single genus.{{cite web|last=Shultz |first=Jeff |url=http://www.life.umd.edu/entm/shultzlab/vtab/arthropleuridea.htm |title=Arthropleuridea |work=Studies in Arthropod Morphology and Evolution |publisher=University of Maryland |author2=Heather Wilson |accessdate=2006-04-12 |archiveurl=https://web.archive.org/web/20070403054901/http://www.life.umd.edu/entm/shultzlab/vtab/arthropleuridea.htm |archivedate=2007-04-03 |url-status=live }}
Paleobiology
Arthropleurids lived in the moist coal swamps that were common at the time and may have burrowed in the undergrowth. They were either herbivores or detritivores. Besides their size, their most distinguishing features were their legs with eight segments (as many as 30 pairs) and extremely tough exoskeletons. There is no evidence of spiracles, so the animals must have used lungs or gills for respiration.
Most arthropleurideans are thought to have been terrestrial, although, without any known respiratory structure, terrestriality is assumed only by analogy to modern arthropods.{{cite book | last = Fortey | first = Richard | authorlink = Richard Fortey |author2 = R. H. Thomas | title = Arthropod Relationships | year = 1998| publisher = Springer | isbn = 0-412-75420-7}} Early forms, however, including Eoarthropleura (order Eoarthropleurida), appear to have been aquatic.{{citation needed|date=October 2013}} For this reason, some question Arthropleuridea's inclusion among millipedes because no modern aquatic myriapods are known.
Distribution and size
Arthropleuridea is most famous for Arthropleura (order Arthropleurida). Tracks from Arthropleura up to 50 cm wide have been found at Joggins, Nova Scotia.{{cite web | url = http://museum.gov.ns.ca/mnh/nature/tracefossils/english/sections/whodunnit/traces/diplichnites.html | title = The Excitement of Discovery | work = Virtual Museum of Canada | accessdate = 2006-04-17 |url-status=dead |archiveurl=https://web.archive.org/web/20120204055638/http://museum.gov.ns.ca/mnh/nature/tracefossils/english/sections/whodunnit/traces/diplichnites.html |archivedate=February 4, 2012}} Reaching over 2 meters in length, arthropleurids are among the largest arthropods ever to have lived. The lack of large terrestrial vertebrate predators and the highly oxygenic atmosphere at that time probably enabled them to grow so large.{{cite book |author=M. G. Lockley & Christian Meyer |year=2013 |title=Dinosaur Tracks and Other Fossil Footprints of Europe |publisher=Columbia University Press |isbn=9780231504607 |chapter=The tradition of tracking dinosaurs in Europe |pages=25–52 |chapter-url=https://books.google.com/books?id=kji6fde5g-gC&pg=PA32}} It was previously believed that Arthropleura became extinct as the coal swamps dried out. However, many fossils have been discovered after the Carboniferous rainforest collapse. A more recent proposal is that predation by tetrapods and the aridification of the equator caused it to become extinct.{{cite journal |last1=Neil Davies |display-authors=etal |date=Dec 21, 2021 |title=The largest arthropod in Earth history: insights from newly discovered Arthropleura remains (Serpukhovian Stainmore Formation, Northumberland, England) |url=https://jgs.lyellcollection.org/content/early/2021/11/19/jgs2021-115 |journal=Journal of the Geological Society |volume=179 |issue=3 |doi=10.1144/jgs2021-115 |s2cid=245401499}}{{Cite journal |last1=Schneider |first1=Joerg |last2=Lucas |first2=Spencer |last3=Werneburg |first3=Ralf |last4=Rößler |first4=Ronny |date=2010-05-01 |title=Euramerican Late Pennsylvanian/Early Permian arthropleurid/tetrapod associations – implications for the habitat and paleobiology of the largest terrestrial arthropod |url=https://www.researchgate.net/publication/257768383 |journal=New Mexico Museum of Natural History and Science Bulletin |volume=49 |pages=49–70}} Arthropleura has been found from the Upper Carboniferous of Europe and North America.
Eoarthropleura has been found from the Upper Silurian through the Upper Devonian of Europe and North America.{{cite journal |author=William Shear & Paul Selden |year=1995 |title=Eoarthropleura (Arthropoda, Arthropleurida) from the Silurian of Britain and the Devonian of North America |journal=Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen |volume=196 |issue=3 |pages=347–375 |doi=10.1127/njgpa/196/1995/347 |url=http://www.paulselden.net/uploads/7/5/3/2/7532217/eoarthropleura.pdf }}
Microdecemplex, of the order Microdecemplicida, was dwarfed by the other Arthropleurideans, at just a few millimeters long. The genus is known from the Middle through Upper Devonian of New York state, USA. This genus, however, is suggested to reject from Arthropleuridea after research of well-preserved specimen of Arthropleura.{{Cite journal |last1=Lhéritier |first1=Mickaël |last2=Edgecombe |first2=Gregory D. |last3=Garwood |first3=Russell J. |last4=Buisson |first4=Adrien |last5=Gerbe |first5=Alexis |last6=Koch |first6=Nicolás Mongiardino |last7=Vannier |first7=Jean |last8=Escarguel |first8=Gilles |last9=Adrien |first9=Jérome |last10=Fernandez |first10=Vincent |last11=Bergeret-Medina |first11=Aude |last12=Perrier |first12=Vincent |date=2024-10-11 |title=Head anatomy and phylogenomics show the Carboniferous giant Arthropleura belonged to a millipede-centipede group |journal=Science Advances |language=en |volume=10 |issue=41 |pages=eadp6362 |doi=10.1126/sciadv.adp6362 |issn=2375-2548 |pmc=11463278 |pmid=39383233|bibcode=2024SciA...10P6362L }}
Classification and placement
After several decades of uncertainty, Arthropleuridea was placed within the Diplopoda in the year 2000. However, there is still controversy regarding the relationships of the three orders to living millipede groups.{{cite journal|last=Shear|first=William A.|author2=Edgecombe, Gregory D.|title=The geological record and phylogeny of the Myriapoda|journal=Arthropod Structure & Development|year=2010|volume=39|issue=2–3|pages=174–190|doi=10.1016/j.asd.2009.11.002|pmid=19944188|bibcode=2010ArtSD..39..174S }}{{cite journal|last=Sierwald|first=Petra|author2=Bond, Jason E.|title=Current Status of the Myriapod Class Diplopoda (Millipedes): Taxonomic Diversity and Phylogeny|journal=Annual Review of Entomology|year=2007|volume=52|issue=1|pages=401–420|doi=10.1146/annurev.ento.52.111805.090210|pmid=17163800}} Some authors place Arthropleuridea within the Chilognatha, as a sister group to all living Chilognathan millipedes (Pentazonia + Helminthomorpha).{{cite journal|last=Wilson|first=Heather M.|author2=Shear, William A.|title=Microdecemplicida, a new order of minute arthropleurideans (Arthropoda: Myriapoda) from the Devonian of New York State, U.S.A.|journal=Transactions of the Royal Society of Edinburgh: Earth Sciences|year=2000|volume=90|issue=4|pages=351–375|doi=10.1017/S0263593300002674|s2cid=129597005 }}{{cite book|last=Hoffman|first=RL|title=Treatise on Invertebrate Paleontology, Pt. R, Arthropoda 4|year=1969|publisher=Geol. Soc. Am./Univ. Kans. Press|location=Lawrence|pages=R572–606|editor=RC Moore|chapter=Myriapoda, exclusive of Insecta}} An alternate hypothesis breaks up the subclass: placing the orders Arthropleurida and Eoarthropleurida within the basal Penicillata (as sister to the living Polyxenida), and leaving only Microdecemplicida as a sister group to the living Chilognatha.{{cite journal|last=Kraus|first=O|author2=C. Brauckman|title=Fossil giants and surviving dwarfs. Arthropleurida and Pselaphognatha (Ateolocerata, Diplopoda): characters, phylogenetic relationships and construction|journal=Verh. Naturwiss. Ver. Hamburg|year=2003|volume=40|issue=5|pages=5–50}} Under this hypothesis, Arthropleuridea would be paraphyletic.
See also
- Archipolypoda, another extinct group of millipedes including the earliest known air-breathing animal
- Euthycarcinoidea, a group of enigmatic arthropods that may be ancestral to myriapods
- Colonization of land, major evolutionary stages leading to terrestrial organisms
References
{{Reflist|32em}}
{{Millipedes|extinct}}
{{Taxonbar|from=Q4797674}}
Category:Prehistoric arthropod taxa