Search results
Results from the WOW.Com Content Network
Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and Mollisonia present by this time. [2] The surviving marine species include the four species of xiphosurans (horseshoe crabs), and possibly the 1,300 species of pycnogonids (sea spiders), if the latter are indeed chelicerates.
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.
The jumping spider Phidippus audax.The basal parts of the chelicerae are the two iridescent green mouthparts. The chelicerae (/ k ə ˈ l ɪ s ər iː /) are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders.
While some literature around the 2000s suggests they may be a sister group to all other living arthropods, [8] [9] their traditional classification as a member of chelicerates alongside horseshoe crabs and arachnids has regained wide support in subsequent studies. [10] [11] [6]
The name "Mandibulata" was originally used for a subgroup of insects by Joseph Philippe de Clairville in 1798. [7] In the 1930s, Robert Evans Snodgrass used the name to encompass myriapods, hexapods and crustaceans, which he considered to be united by a number of morphological simlarities, including but not limited to the presence of mandibles. [8]
Ecdysozoa (/ ˌ ɛ k d ɪ s oʊ ˈ z oʊ ə /) is a group of protostome animals, [9] including Arthropoda (insects, chelicerates (including arachnids), crustaceans, and myriapods), Nematoda, and several smaller phyla.
Dekatriata is a clade of planatergan chelicerates including the groups Arachnida, Chasmataspidida, Eurypterida [1] and additionally two stem-genera Winneshiekia and Houia. [2] ...
The Crustacea were generally considered the closest relatives of the Uniramia, and sometimes these were united as Mandibulata.However, the competing hypothesis — that Crustacea and Hexapoda form a monophyletic group, the Pancrustacea, to which the Myriapoda are the closest relatives — has support from molecular and fossil evidence.