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Setapedites
''Setapedites'' is an extinct genus of Ordovician offacolid chelicerates from the Fezouata Formation of Morocco. The genus contains a single species, ''Setapedites abundantis''. Description ''Setapedites'' is roughly 6 mm long excluding the telson, with eleven body segments and a prosoma with six appendage pairs. The first appendage pairs are elongated chelicerae, with the other five being biramous appendages. The exopods of these appendages bear setae on their tips, hence the name ''Setapedites''. The opisthosoma is divided into a pre-abdomen and an abdomen. Each pre-abdomen segment has both a pair of appendages and on the tergites, leaf-shaped tergopleurae, although somite 14 and all of the abdominal somites lack appendages. The first pre-abdominal somite has a large, flap-like exopod. The abdominal somites have fused tergites and sternites forming ring-shaped structures, alongside two pairs of spines derived from the tergopleurae. Under the 11th tergite, a small, symmetri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fezouata Formation
The Fezouata Formation or Fezouata Shale is a geological formation in Morocco which dates to the Ordovician, Early Ordovician.Fezouata Formation at Fossilworks.orgFezouata Shale at Fossilworks.orgLower Fezouata Formation at Fossilworks.org [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Offacolidae
Offacolidae is a family of basal euchelicerate arthropods from the Ordovician and Silurian of Europe, Morocco and North America. The family is united by several features, including paddle-like sixth post-cheliceral appendages, elongated chelicerae, and reduced first tergites, although these are apparently not unique to the clade, but instead euchelicerate or wider synapomorphies, therefore making the clade paraphyletic. Alongside this, ''Offacolus'' may be more basal than the rest of the clade, as its seventh exopod pair is unreduced and it has a bipartite telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ..., among other features. They share with most other euchelicerates a wide carapace, which has led to them being placed in the paraphyletic “ Synziphosurina” for a long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelicerata
The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mites, among many others), as well as a number of extinct lineages, such as the eurypterids (sea scorpions) and chasmataspidids. Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and '' Mollisonia'' present by this time. 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. On the other hand, there are over 77,000 well-identified species of air-breathing chelicerates, and there may be about 500,000 unidentified species. Like all arthropods, chelicerates have segmented bodies with jointed limbs, all covered in a cuti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Offacolus
''Offacolus'' is an extinct genus of euchelicerate, a group of chelicerate arthropods. Its only species, ''O. kingi'', has been found in deposits from the Silurian period ( Homerian epoch) in the Wenlock Series Lagerstätte of Herefordshire, England. The genus is named after Offa, a king from the ancient kingdom of Mercia, and ''colus'', a person who dwelled among (this time referring to) the Offa's Dyke. The species name honors Robert Joseph King, a British mineralogist who found the fossils of ''Offacolus''. Similar to ''Dibasterium'', ''Offacolus'' possess limb-like exopods (outer limb branches) on appendage II to V, a character suggest to be plesiomorphic (observable in the putative stem-chelicerate taxon Habeliida) and lost within the prosomapod clade. Classification ''Offacolus'' was originally described as an arthropod with chelicerate affinities, with detailed redescription done by Sutton ''et al.'' 2002 further suggested it to be unambiguously a chelicerate arthro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euchelicerata
The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mites, among many others), as well as a number of extinct lineages, such as the eurypterids (sea scorpions) and chasmataspidids. Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and '' Mollisonia'' present by this time. 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. On the other hand, there are over 77,000 well-identified species of air-breathing chelicerates, and there may be about 500,000 unidentified species. Like all arthropods, chelicerates have Segmentation (biology), segmented bodies with jointed limbs, all cove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Megaannum, Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypic Taxon
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of Genus, genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. Theoretical implications Monotypic taxa present several important theoretical challenges in biological classification. One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seta
In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, Scale (insect anatomy), scales, or Common name, informally, hairs. The setal membrane is not Cuticle, cuticularized, so movement is possible. Annelid setae are stiff bristles present on the body. They allow earthworms and their relatives to attach to the surface and prevent backsliding during peristaltic motion. These hairs make it difficult to pull a worm straight from the ground. Setae in oligochaetes (the group including earthworms) are largely composed of chitin. They are classified according to the limb to which they are attached; for instance, notosetae are attached to notopodia; neurosetae to neuropodia. The setae on polychaete worms are referred to as chaeta due to their differing morphology. Crustaceans have mechano- and chemos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibasterium
''Dibasterium'' is an extinct genus of euchelicerate, a group of chelicerate arthropods. Fossils of the single and type species, ''D. durgae'', have been discovered in the Coalbrookdale Formation of the Middle Silurian period (Homerian age) in Herefordshire, England (in the United Kingdom). The name of the genus is derived from the Latin words ''dibamos'' ("on two legs") and '' mysterium'' ("mystery"), meaning "mystery on two legs" and referring to its prosomal (of the head) limbs. The species name ''durgae'' comes from Durga, a Hindu goddess Hindu deities are the gods and goddesses in Hinduism. Deities in Hinduism are as diverse as its traditions, and a Hindu can choose to be polytheistic, pantheistic, monotheistic, monistic, even agnostic, atheistic, or humanist. Julius J. Lip ... with many arms. References Euchelicerata Fossils of England Silurian arthropods of Europe Silurian animals Wenlock first appearances Homerian extinctions Fossil taxa described in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habelia
''Habelia'' is a genus of extinct arthropod from the Middle Cambrian, thought to be one of the earliest known relatives of chelicerates. Its fossils have been found in the Burgess Shale in British Columbia, Canada. Fifty-four specimens of ''Habelia'' are known from the Greater Phyllopod bed, where they comprise 0.1% of the community. Description The body is divided into two main segments. The cephalon ("head")/prosoma with seven segments/8 somites, and the trunk with 12 segments, making for a total of 19 body segments. The body is around in length excluding the long telson that terminates the body. The head, which is 25% wider than it is long, makes up about 30% of the total body length, and has a bulging shape, with triangular genal spines projecting outward at its edges. It housed the stomach of the animal. The head bore a pair of spherical compound eyes, which were accommodated by notches in the head shield. A hypostome- labrum complex was present, with the mouth openling v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bunaia
''Bunaia'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Bunaia'' was tentatively placed as part of the clade Planaterga, however a 2024 study found it to be within Offacolidae instead. The genus contains at least one species: ''Bunaia woodwardi'' from the Silurian period in Svalbard, Norway and the Bertie Group of Ontario Description Initially, the species was known only from poorly preserved specimens composed of semicircular carapace, fragments of opisthosoma and disarticulated telson. The aforementioned 2024 study described additional specimens, which revealed "a pair of elongated chelicerae in the prosoma, followed posteriorly by five pairs of biramous appendages, a first pre-abdomen somite bearing a pair of paddle-like uniramous appendages ( exopods) and a ventral pretelsonic process." Taxonomy The placement of ''"Bunaia" heintzi'' (known only by a single carapace from the Silurian period in the United States The Unite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
