What does xiphosura mean?
Definitions for xiphosura
xipho·sura
This dictionary definitions page includes all the possible meanings, example usage and translations of the word xiphosura.
Princeton's WordNet
Xiphosura, order Xiphosuranoun
horseshoe crabs and extinct forms
Wikipedia
Xiphosura
Xiphosura () is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Limulidae). They first appeared in the Hirnantian (Late Ordovician). Currently, there are only four living species. Xiphosura contains one suborder, Xiphosurida, and several stem-genera. The group has hardly changed in appearance in hundreds of millions of years; the modern horseshoe crabs look almost identical to prehistoric genera and are considered to be living fossils. The most notable difference between ancient and modern forms is that the abdominal segments in present species are fused into a single unit in adults. Xiphosura were historically placed in the class Merostomata, although this term was intended to encompass also the eurypterids, whence it denoted what is now known to be an unnatural (paraphyletic) group (although this is a grouping recovered in some recent cladistic analyses). Although the name Merostomata is still seen in textbooks, without reference to the Eurypterida, some have urged that this usage should be discouraged. The Merostomata label originally did not include Eurypterida, although they were added in as a better understanding of the extinct group evolved. Now Eurypterida is classified within Sclerophorata together with the arachnids, and therefore, Merostomata is now a synonym of Xiphosura. One recent study places Xiphosura within the Arachnida as the sister group of Ricinulei.
ChatGPT
xiphosura
Xiphosura is an order of marine arthropods that includes species commonly known as horseshoe crabs. They are characterized by their long, pointed tail and large, rounded upper shell. Despite their name, horseshoe crabs are more closely related to spiders and scorpions than to crabs.
Webster Dictionary
Xiphosura
see Xiphura
Wikidata
Xiphosura
Xiphosura is an order of marine chelicerates that includes a large number of extinct lineages and only four recent species in the family Limulidae, which include the horseshoe crabs. The group has hardly changed in millions of years; the modern horseshoe crabs look almost identical to prehistoric genera such as the Jurassic Mesolimulus, and are considered to be living fossils. The most notable difference between ancient and modern forms is that the abdominal segments in present species are fused into a single unit in adults. Xiphosura were traditionally placed in the class Merostomata, although this term was intended to encompass also the eurypterids, whence it denoted what is now known to be an unnatural group. Although the name Merostomata is still seen in textbooks, without reference to the Eurypterida, some have urged that this usage should be discouraged. The Merostomata label originally did not include Eurypterida, although they were added in as a better understanding of the extinct group evolved. However, as the similarities, which were once thought to tie the group together, are now understood to be symplesiomorphies, it seems that abandoning the term altogether to avoid any confusion arising from these historical usages of the term is the best strategy.
Matched Categories
Numerology
Chaldean Numerology
The numerical value of xiphosura in Chaldean Numerology is: 2
Pythagorean Numerology
The numerical value of xiphosura in Pythagorean Numerology is: 5
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"xiphosura." Definitions.net. STANDS4 LLC, 2024. Web. 28 Mar. 2024. <https://www.definitions.net/definition/xiphosura>.
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