Merostomata: Difference between revisions
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==History== | ==History== | ||
The scientific consensus at the beginning of the 20th century was that these two marine groups were closely related, and only more distantly related to the terrestrial [[Arachnid]]a.<ref>{{cite book |editor1=Richard A. Fortey |editor2=Richard H. Thomas |year=1998 |title=Arthropod relationships |series=Volume 55 of Systematics Association Series |publisher=[[Springer Verlag]] |isbn=978-0-412-75420-3 |chapter=The early history and phylogeny of the chelicerates |author1=J. A. Dunlop |author2=P. A. Selden |name-list-style=amp |pages=221–236 |chapter-url=https://books.google.com/books?id=Pj-q9eHyIx0C&pg=PA221 }} Also available as [http://homepage.mac.com/paulselden/Sites/Website/DunlopSelden1997.pdf PDF]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Some more recent analyses suggest the grouping Merostomata is not [[monophyly|monophyletic]], with Xiphosura being basal to a [[clade]] comprising Eurypterida and Arachnida.<ref name="Tudge">{{cite book |author=Colin Tudge |year=2002 |title=The variety of life: a survey and a celebration of all the creatures that have ever lived |publisher=[[Oxford University Press]] |isbn=978-0-19-860426-6 |chapter=Spiders, scorpions, mites, eurypterids, horseshoe crabs, and sea spiders. Subphylum Chelicerata and Subphylum Pycnogonida |pages=309–326 |chapter-url=https://books.google.com/books?id=YW-2gnuU0L0C&pg=PA312}}</ref> Other recent analyses support the monophyly of this group.<ref name=Garw>{{cite journal|title=Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders|first1=Russell J.|last1=Garwood|first2=Jason A.|last2=Dunlop|year=2014|journal=PeerJ|volume=2| | The scientific consensus at the beginning of the 20th century was that these two marine groups were closely related, and only more distantly related to the terrestrial [[Arachnid]]a.<ref>{{cite book |editor1=Richard A. Fortey |editor2=Richard H. Thomas |year=1998 |title=Arthropod relationships |series=Volume 55 of Systematics Association Series |publisher=[[Springer Verlag]] |isbn=978-0-412-75420-3 |chapter=The early history and phylogeny of the chelicerates |author1=J. A. Dunlop |author2=P. A. Selden |name-list-style=amp |pages=221–236 |chapter-url=https://books.google.com/books?id=Pj-q9eHyIx0C&pg=PA221 }} Also available as [http://homepage.mac.com/paulselden/Sites/Website/DunlopSelden1997.pdf PDF]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Some more recent analyses suggest the grouping Merostomata is not [[monophyly|monophyletic]], with Xiphosura being basal to a [[clade]] comprising Eurypterida and Arachnida.<ref name="Tudge">{{cite book |author=Colin Tudge |year=2002 |title=The variety of life: a survey and a celebration of all the creatures that have ever lived |publisher=[[Oxford University Press]] |isbn=978-0-19-860426-6 |chapter=Spiders, scorpions, mites, eurypterids, horseshoe crabs, and sea spiders. Subphylum Chelicerata and Subphylum Pycnogonida |pages=309–326 |chapter-url=https://books.google.com/books?id=YW-2gnuU0L0C&pg=PA312}}</ref> Other recent analyses support the monophyly of this group.<ref name=Garw>{{cite journal|title=Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders|first1=Russell J.|last1=Garwood|first2=Jason A.|last2=Dunlop|year=2014|journal=PeerJ|volume=2|article-number=e641|doi=10.7717/peerj.641|pmid=25405073|pmc=4232842 |doi-access=free }}</ref> The Xiphosura are estimated to have diverged from the Arachnida {{Ma|480}}.<ref>{{cite journal |author1=Davide Pisani |author2=Laura L. Poling |author3=Maureen Lyons-Weiler |author4=S. Blair Hedges |year=2004 |title=The colonization of land by animals: molecular phylogeny and divergence times among arthropods |journal=[[BMC Biology]] |volume=2 |page=1 |pmc=333434 |doi=10.1186/1741-7007-2-1 |pmid=14731304 |doi-access=free }}</ref> | ||
The shared features of the two groups traditionally grouped in the Merostomata are now thought to be retentions of primitive conditions ([[symplesiomorphy|symplesiomorphies]]), thus the name Merostomata has been recommended to be abandoned.<ref name="Tudge"/> | The shared features of the two groups traditionally grouped in the Merostomata are now thought to be retentions of primitive conditions ([[symplesiomorphy|symplesiomorphies]]), thus the name Merostomata has been recommended to be abandoned.<ref name="Tudge"/> | ||
However, a 2022 analysis recovered the monophyly of Merostomata, as opposed to a monophyletic Arachnida, with Xiphosura as the only modern representative in a derived position, indicating the convergence of several characteristics that supposedly united the arachnids.<ref>{{Cite journal |last1=Ballesteros |first1=Jesús A |last2=Santibáñez-López |first2=Carlos E |last3=Baker |first3=Caitlin M |last4=Benavides |first4=Ligia R |last5=Cunha |first5=Tauana J |last6=Gainett |first6=Guilherme |last7=Ontano |first7=Andrew Z |last8=Setton |first8=Emily V W |last9=Arango |first9=Claudia P |last10=Gavish-Regev |first10=Efrat |last11=Harvey |first11=Mark S |last12=Wheeler |first12=Ward C |last13=Hormiga |first13=Gustavo |last14=Giribet |first14=Gonzalo |last15=Sharma |first15=Prashant P |date=2022-02-03 |editor-last=Teeling |editor-first=Emma |title=Comprehensive Species Sampling and Sophisticated Algorithmic Approaches Refute the Monophyly of Arachnida |url=https://academic.oup.com/mbe/article/doi/10.1093/molbev/msac021/6522129 |journal=Molecular Biology and Evolution |language=en |volume=39 |issue=2 | | However, a 2022 analysis recovered the monophyly of Merostomata, as opposed to a monophyletic Arachnida, with Xiphosura as the only modern representative in a derived position, indicating the convergence of several characteristics that supposedly united the arachnids.<ref>{{Cite journal |last1=Ballesteros |first1=Jesús A |last2=Santibáñez-López |first2=Carlos E |last3=Baker |first3=Caitlin M |last4=Benavides |first4=Ligia R |last5=Cunha |first5=Tauana J |last6=Gainett |first6=Guilherme |last7=Ontano |first7=Andrew Z |last8=Setton |first8=Emily V W |last9=Arango |first9=Claudia P |last10=Gavish-Regev |first10=Efrat |last11=Harvey |first11=Mark S |last12=Wheeler |first12=Ward C |last13=Hormiga |first13=Gustavo |last14=Giribet |first14=Gonzalo |last15=Sharma |first15=Prashant P |date=2022-02-03 |editor-last=Teeling |editor-first=Emma |title=Comprehensive Species Sampling and Sophisticated Algorithmic Approaches Refute the Monophyly of Arachnida |url=https://academic.oup.com/mbe/article/doi/10.1093/molbev/msac021/6522129 |journal=Molecular Biology and Evolution |language=en |volume=39 |issue=2 |article-number=msac021 |doi=10.1093/molbev/msac021 |issn=0737-4038 |pmc=8845124 |pmid=35137183}}</ref> | ||
== References == | == References == | ||
Latest revision as of 14:15, 29 September 2025
Template:Short description Template:Automatic taxobox
Merostomata is a class of chelicerate arthropods that contains the extinct Eurypterida (sea scorpions) and the extant Xiphosura (horseshoe crabs). The term was originally used by James Dwight Dana to refer to Xiphosura only, but was emended by Henry Woodward to cover both groups.
Etymology
The name "Merostomata" derives from the Greek roots Script error: No such module "Lang". (Script error: No such module "Lang"., "thigh") and Script error: No such module "Lang". (Script error: No such module "Lang"., "mouth"), in reference to the animals' possession of appendages which are mouthparts at their proximal end, but swimming legs at their distal end.[1]
History
The scientific consensus at the beginning of the 20th century was that these two marine groups were closely related, and only more distantly related to the terrestrial Arachnida.[2] Some more recent analyses suggest the grouping Merostomata is not monophyletic, with Xiphosura being basal to a clade comprising Eurypterida and Arachnida.[3] Other recent analyses support the monophyly of this group.[4] The Xiphosura are estimated to have diverged from the Arachnida Template:Ma.[5]
The shared features of the two groups traditionally grouped in the Merostomata are now thought to be retentions of primitive conditions (symplesiomorphies), thus the name Merostomata has been recommended to be abandoned.[3]
However, a 2022 analysis recovered the monophyly of Merostomata, as opposed to a monophyletic Arachnida, with Xiphosura as the only modern representative in a derived position, indicating the convergence of several characteristics that supposedly united the arachnids.[6]
References
External links
Template:Arthropods Template:Taxonbar
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