Gnathobase
Gnathobases (from Ancient Greek γνάθος (gnáthos), meaning 'jaw', and βᾰ́σῐς (básis), meaning 'base') are protrusions at the medial base (endites) of the most proximal part of the appendages (basipod/basipodite) of many arthropods. They are paired and are used for food processing, and can also be used in its transportation.[1]
Gnathobases are present in extant and extinct taxa, such as mandibulates (e.g. myriapods, crustaceans, hexapods), chelicerates (e.g. xiphosurans, arachnids,[2] eurypterids), and also in several other groups such as the trilobites.[3]
In Chelicerata
Chelicerates have gnathobases that function in conjunction with chelicerae and in some taxa with other structures.
Arachnida
In arachnids, gnathobases are usually present in the coxae of the pedipalps (hence they are called "gnathocoxae"), but can also be present in the first (e.g. Trigonotarbida)[2] and second (e.g. Opiliones) pair of walking legs. They are present in Arachnopulmonata (e.g. spiders, scorpions, Pedipalpi) but also in other orders such as Opiliones and Solifugae.
Eurypterida
In eurypterids both pedipalps and all walking legs (pairs of appendages II to VI) have the basipods with gnathobases that function together with the metastoma. This distribution occurs similarly in the related group Chasmataspidida.[4]
Xiphosura
In xiphosurans gnathobases are found on the basipods of the pedipalps and walking legs, similar to those of eurypterids. They function with chilaria (sg. chilarium), a pair of reduced appendages that prevent food from escaping.[5]
Other chelicerates
Gnathobases are also found in other groups of chelicerates, such as in the mandible-like basipods of Habelia and Mollisonia.[6]
In Mandibulata
Mandibles, the eponymous appendages of the Mandibulata, are thought to have originated from thoracic legs possessing endites (gnathobases).[7]
Crustacea
Crustaceans are a very diverse group and the morphology of their mouthparts are variable. They usually have gnathobases in the mandibles, maxillae and maxillulae, and also in the thoracopods, either the first pairs (which are usually developed as maxillipeds) or all of them.
References
- ↑ Allaby, Michael (2009). "gnathobase". A Dictionary of Zoology. Oxford University Press. doi:10.1093/acref/9780199233410.001.0001. ISBN 978-0-19-923341-0. Search this book on
- ↑ 2.0 2.1 Haug, Carolin (2020-08-13). "The evolution of feeding within Euchelicerata: data from the fossil groups Eurypterida and Trigonotarbida illustrate possible evolutionary pathways". PeerJ. 8: e9696. doi:10.7717/peerj.9696. ISSN 2167-8359. Unknown parameter
|s2cid=ignored (help) - ↑ Bicknell, Russell D. C.; Ledogar, Justin A.; Wroe, Stephen; Gutzler, Benjamin C.; Watson, Winsor H.; Paterson, John R. (2018-10-24). "Computational biomechanical analyses demonstrate similar shell-crushing abilities in modern and ancient arthropods". Proceedings of the Royal Society B: Biological Sciences. 285 (1889). 20181935. doi:10.1098/rspb.2018.1935. ISSN 0962-8452. PMC 6234888. PMID 30355715.
- ↑ Lamsdell, James C.; Gunderson, Gerald O.; Meyer, Ronald C. (2019-01-08). "A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida". BMC Evolutionary Biology. 19 (1): 8. doi:10.1186/s12862-018-1329-4. ISSN 1471-2148. PMC 6325806. PMID 30621579.
- ↑ Bicknell, Russell D.C; Paterson, John R; Caron, Jean-Bernard; Skovsted, Christian B (2017). "The gnathobasic spine microstructure of recent and Silurian chelicerates and the Cambrian artiopodan Sidneyia : Functional and evolutionary implications". Arthropod Structure & Development. 47 (1): 12–24. doi:10.1016/j.asd.2017.12.001. PMID 29221679. Unknown parameter
|s2cid=ignored (help) - ↑ Aria, Cédric; Caron, Jean-Bernard (2019). "A middle Cambrian arthropod with chelicerae and proto-book gills". Nature. 573 (7775): 586–589. doi:10.1038/s41586-019-1525-4. ISSN 1476-4687.
- ↑ Izquierdo-López, Alejandro; Caron, Jean-Bernard (2022). "The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited". Royal Society Open Science. 9 (12). doi:10.1098/rsos.220933. ISSN 2054-5703. PMC 9727825 Check
|pmc=value (help). PMID 36483757 Check|pmid=value (help).
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