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Artiopodans
Artiopoda is a clade of extinct arthropods that includes trilobites and their close relatives. It was erected by Hou and Bergström in 1997 to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomorpha. Trilobites, in part due to abundance of findings owing to their mineralized exoskeletons, are by far the best recorded, diverse, and long lived members of the clade. Other members, which lack mineralised exoskeletons, are known mostly from Cambrian deposits. Description According to Stein and Selden (2012) artiopods are recognised by the possession of filiform antennulae, limbs with bilobate exopods (upper branches), with the proximal (closest to base of the limb) lobe being elongate and bearing a lamella, while the distal (further from the limb base) lobe is paddle-shaped and setiforous (bearing hair-or bristle like structures). The limb endopod (inner, leg-like branch) has seven podomeres/segments, with first four podomeres bear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostida
Agnostida are an order of extinct arthropods which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda. They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician. Systematics The Agnostida are divided into two suborders — Agnostina and Eodiscina — which are then subdivided into a number of families. As a group, agnostids are isopygous, meaning their pygidium is similar in size and shape to their cephalon. Most agnostid species were eyeless. The systematic position of the order Agnostida within the class Trilobita remains uncertain, and there has been c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhiwenia
''Zhiwenia'' is a genus of artiopods that existed during Stage 3 of the Cambrian period and was uncovered in the Xiaoshiba Lagerstätte in China. Only one species is known, ''Zhiwenia coronata''. It is the sister taxon of '' Australimicola'' in the newly defined clade Protosutura, which is itself the sister group of Trilobitomorpha Artiopoda is a clade of extinct arthropods that includes trilobites and their close relatives. It was erected by Hou and Bergström in 1997 to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomor .... References Cambrian arthropods of Asia Artiopoda {{Paleo-arthropod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheloniellon
''Cheloniellon'' is a monotypic genus of cheloniellid arthropod, known only by one species, ''Cheloniellon calmani'', discovered from the Lower Devonian Hunsrück Slate of Germany. Morphology ''Cheloniellon'' range about 20 centimeters in body length (excluding appendages). The flattened, ovoid body compose of 11 tergites (dorsal exoskeleton), all but the posteriormost are laterally expanded and covered the appendages underneath each of them. The boundaries between tergites have a radiated appearance. Dorsal surface of the first tergite have a pair of kidney-shaped eyes. Based on the differentiation of corresponding appendages, the first 2 tergites and the remaining 9 tergites were interpreted as those of cephalon (head) and trunk, respectively. Contray to the widely-referred reconstruction by Stürmer & Bergström (1978), but as most of the Cheloniellids, There is no evidence of telson (a medial tail-like terminal structure) in any described fossil materials.Wendruff, Andrew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheloniellid
Cheloniellida is a taxon (usually referred to as an order) of extinct Paleozoic arthropods. As of 2018,Wendruff, Andrew James, et al. "New cheloniellid arthropod with large raptorial appendages from the Silurian of Wisconsin, USA." BioRxiv (2018): 407379/ref> 7 monotypic genera of cheloniellids had been formally described, whose fossils are found in marine strata ranging from Ordovician to Devonian in age. Cheloniellida has a controversial phylogenetic position, with previous studies associated it as either a member or relative of various fossil and extant arthropod taxa. It was later accepted as a member of Vicissicaudata within Artiopoda. Morphology The flattened, ovoid body of cheloniellid comprises an eye-bearing cephalon (head) and segmented trunk region, dorsally divided by a series of tergites (dorsal exoskeleton). The cephalon could be divided into procephalon and gnathocephalon. Compared to other members of Artiopoda, the head shield (dorsal exoskeleton of cephalon) of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kwanyinaspis
''Kwanyinaspis'' is a genus of arthropod from the Cambrian aged Chengjiang biota of Yunnan, China. It was described in 2005 based on a single specimen, ELI-2004001. Around 6 cm long, It has twelve trunk tergites with well developed posterior facing pleural spines, along with a tail spine and ventral eyes. In the original description, it was tenatively considered a member of Aglaspidida. However, later studies have considered it a trilobitomorph, and possibly the closest known relative of trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...s. References {{Taxonbar, from1=Q113427154 Artiopoda Prehistoric arthropod genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thulaspis
''Thulaspis'' is an extinct genus of artiopodan arthropod from the Cambrian Stage 3 aged Sirius Passet site in Greenland. It is thought to be a close relative of '' Squamacula'', and is possibly one of the most basal members of Artiopoda. Description ''Thulaspsis'' was relatively large-sized. The largest specimen is about wide and long. The carapace is overall oval-shaped was convex and likely stiff in life, with a raised central axis. The head is broad and bears a pair of antennae, which have at least 20 rectangular segments, and likely two pairs of biramous (two branched) limbs.The body has 15 thoracic segments, which curve forwards in the first few segments, before becoming straight in the fourth and fifth segments, then increasingly posteriorly curved in subsequent segments. At least the first 11 thoracic segments are associated with pairs of biramous limbs. The biramous limbs have robust endopods (lower, leg-like branches), and flap-shaped exopods (upper branches). The b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conciliterga
Conciliterga is an extinct order of artiopod arthropods, exclusively known from the Middle Cambrian. They are placed within the clade Trilobitomorpha, which contains the trilobites and their closest relatives. Conciliterga is united by their partially or wholly fused tergites, which gives rise to their name (Conciliterga is composed of the Latin words ''concilio'' ("to unite") and ''tergum'' ("back")). Most members of this clade are elliptical in body shape, with 6-9 thoracic tergites, a head shield and a large tail shield in the members with incomplete tergite fusion. These members, which formerly comprised the order Helmetiida (which currently only contains ''Helmetia'', '' Rhombicalvaria'' and '' Kuamaia''), also have various other characteristics like a lack of axial region, rostral and pararostral plates on the head, and compound eyes near the rostral plate. In addition, they have essentially uniform biramous limbs running down the body with coarse endopods, alongside a pair ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilobita
Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most successful of all early animals, existing in oceans for almost 270million years, with over 22,000 species having been described. Because trilobites had wide diversity and an easily fossilized mineralised exoskeleton made of calcite, they left an extensive fossil record. The study of their fossils has facilitated important contributions to biostratigraphy, paleontology, evolution, evolutionary biology, and plate tectonics. Trilobites are placed within the clade Artiopoda, which includes many organisms that are morphologically similar to trilobites, but are largely unmineralised. The relationship of Artiopoda to other arthropods is uncertain. Trilobites evolved into many ecological niches; some moved over the seabed as predators, scavengers, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthomeridion
''Acanthomeridion'' is an extinct arthropod found in the Cambrian Stage 3 aged Chengjiang biota deposits of Yunnan, China. It is a member of Artiopoda, placing it as a close relative of trilobites. Morphology Specimens of ''Acanthomeridion'' range in length from measured along the midline (sagittal plane). The exoskeleton was unmineralised. The head shield was roughly triangular in shape, rounded towards the front. A pair of compound eyes were accommodated by notches at the posterior edge of the head shield. Over the course of growth, the head became proportionally wider relative to body length. On the underside of the head, a pair of teardrop-shaped plates attached to the head shield, with their outer posterior edges forming a pair of spines projecting backwards from the head. The mouth region had an axe-shaped hypostome. The head bore four pairs of appendages, including a pair of antennae with at least 43 segments, with these segments becoming narrower and shorter towards t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthroaspis
''Arthroaspis'' is an extinct genus of arthropod known from the Cambrian aged Sirius Passet Lagerstatte in Greenland. It is relatively large in size for Cambrian arthropods, attaining a length of up to 215 mm. It is a common component of the Passet fauna, being located at multiple localities within the formation. It possessed 14 tergites. In the describing paper, it was recovered as a member of a non-monophyletic Artiopoda. It has subsequently been considered a potential close relative of nektaspids. Another paper from 2025 which re-analyzed the Burgess Shale artiopod '' Helmetia expansa'', found ''Arthroaspis'' to be a basal member of the Conciliterga, within the Trilobitomorpha Artiopoda is a clade of extinct arthropods that includes trilobites and their close relatives. It was erected by Hou and Bergström in 1997 to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomor .... References {{Taxonbar, from=Q96372401 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nektaspida
Nektaspida (also called Naraoiida, Nektaspia and Nectaspida) is an extinct order of non- mineralised artiopodan arthropods. They are known from the lower-Cambrian to the upper Silurian. Originally classified as trilobites, which they superficially resemble, they are now placed as close relatives as members of the Trilobitomorpha within Artiopoda. The order is divided into three major families; Emucarididae, Liwiidae, and Naraoiidae. Naming history and taxonomic placement The order was originally proposed by Raymond in 1920 as Nektaspia. Størmer corrected it to Nectaspida for the 1959 ''Treatise on Invertebrate Paleontology'' to conform with the names of the other trilobite orders. Whittington described it in 1985 with the spelling Nektaspida; the revised 1997 Treatise by Raymond and Fortey uses this spelling, as do other modern works. Whittington (1985) placed the order in the Trilobita. Cotton & Braddy (2000) place it in a new "Trilobite clade" containing the Trilobita, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
