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Tanazios
''Tanazios'' is a genus of Silurian stem-mandibulate from the Coalbrookdale Formation of England. Description ''Tanazios'' has a head shield that is semicircular in shape, divided into a fringe and an axial (central) region. The fringe margins meet somewhat abruptly at the front of the shield, with a long projection pointing from their back corners and six pairs of horn-like structures at the sides. The axial region is semi-ovoid in shape, around 3 times wider than long, and bears a wide furrow running down its length. At the sides there is a narrow ledge which pinches out towards the back and continues as the inner trunk pleurae. No eyes seem to be present. The hypostome is subrectangular and extends from the antennulae to the mandibular gnathobases, with an anterior margin bearing four small spines and a convex posterior margin with a lip-like structure which may be the labrum. The antennulae are very short and uniramous, with the antennae being around five times longer a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acheronauta Stimulapis
''Acheronauta'' is a genus of extinct worm-shaped arthropod that lived in the early Silurian (Telychian-Sheinwoodian stages) Waukesha biota fossil site in southeast Wisconsin. This arthropod was first discovered alongside the biota in 1985, but was not fully described until October 2022. This creature was recognized and described as a possible early mandibulate (the grouping of arthropods including crustaceans and hexapods). This description is very important as much of the fauna of the biota remain undescribed, and its discovery has allowed for paleontologists to get a better grasp of the diversity of the arthropod fauna at the site. Multiple phylogenetic analyses were performed, and it was found that this arthropod forms a previously undiscovered clade with the Devonian stem-arthropod ''Captopodus'', and the somewhat enigmatic group Thylacocephala. ''Acheronauta'' has been assessed as a possible basal mandibulate, which are distinguished from other arthropods due to the presen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thylacocephala
The Thylacocephala (from the Greek or ', meaning " pouch", and or ' meaning "head") are group of extinct probable mandibulate arthropods, that have been considered by some researchers as having possible crustacean affinities. As a class they have a short research history, having been erected in the early 1980s. They typically possess a large, laterally flattened carapace that encompasses the entire body. The compound eyes tend to be large and bulbous, and occupy a frontal notch on the carapace. They possess three pairs of large raptorial limbs, and the abdomen bears a battery of small swimming limbs. Their size ranges from ~15 mm to potentially up to 250 mm. Inconclusive claims of thylacocephalans have been reported from the lower lower Cambrian ('' Zhenghecaris''), but later study considered that genus as radiodont or arthropod with uncertain systematic position. The oldest unequivocal fossils are Upper Ordovician and Lower Silurian in age. As a group, the Thylacocephala s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Captopodus
''Captopodus'' is an extinct genus of stem-mandibulate known from the Early Devonian. This creature was described in 2012 from four fossils found in the Hunsrück Slate, an early Devonian lagerstätten in Germany that represents one of the few marine sites from the Devonian with soft tissue preservation. Description ''Captopodus'' is a vermiform (worm-like) arthropod, with over 66 trunk segments each containing a biramous limb pair, with the final segment containing a caudal furca. The head region contains two pairs of appendages, one being antennae, and the other resembling the grasping legs of thylacocephalans. It also has cupola-like structures, the function of which is unknown. The animal measures five to ten centimetres long. It is also very similar to, and probably related to the animal ''Acheronauta'', from the Waukesha Biota The Waukesha Biota (also known as Waukesha Lagerstätte, Brandon Bridge Lagerstätte, or Brandon Bridge fauna) is an important fossil site l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cascolus
''Cascolus'' is an extinct genus of stem-mandibulate known from the Coalbrookdale Formation. Description ''Cascolus'' is a long, somewhat vermiform arthropod, roughly 9 millimetres long. It has a head segment containing a head shield, stalked eyes and five pairs of limbs, the first similar to megacheirans and the other four biramous with gnathobases, followed by a nine-segmented thorax and two possibly limbless segments near the posterior. The trunk remains similar in size through tergites 1-4, and then decreases in width onwards into the limbless segments. Ecology ''Cascolus'' appears to have been a nektobenthic animal, possibly a scavenger. Etymology ''Cascolus'' was named in honour of Sir David Attenborough. The genus name derives from "castrum" ("stronghold") and "colus" ("dwelling in"), alluding to the Middle or Old English source for the name "Attenborough". The specific name ''ravitis'' derives from "Ratae" (the Roman name for Leicester), "vita" ("life") and "com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandibulate
The clade Mandibulata constitutes one of the major subdivisions of the phylum Arthropoda, alongside Chelicerata. Mandibulates include the crustaceans, myriapods (centipedes and millipedes, among others), and all true insects. The name "Mandibulata" refers to the mandibles, a modified pair of limbs used in food processing, the presence of which are characteristic of most members of the group. The mandibulates are divided between the extant groups Myriapoda (millipedes and centipedes, among others) and Pancrustacea (including crustaceans and hexapods, the latter group containing insects). Molecular phylogenetic studies suggest that the living arthropods are related as shown in the cladogram below. Crustaceans do not form a monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalbrookdale Formation
Coalbrookdale Formation, earlier known as Wenlock Shale or Wenlock Shale Formation and also referred to as Herefordshire Lagerstätte in palaeontology, is a fossil-rich deposit ('' Konservat-Lagerstätte'') in Powys and Herefordshire at the England–Wales border in UK. It belongs to the Wenlock Series of the Silurian Period within the Homerian Age (about 430 million years ago). It is known for its well-preserved fossils of various invertebrate animals many of which are in their three-dimensional structures. Some of the fossils are regarded as earliest evidences and evolutionary origin of some of the major groups of modern animals. Roderick Murchison first described the geological setting of Coalbrookdale Formation by which he gave the name Silurian in 1935, referring to the Silures, a Celtic tribe of Wales. It is assigned to the Wenlock Group in 1978 based on the age of crustacean fossils found around the region. Robert J. King of the University of Leicester discovered the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of the Paleozoic Era, and the third of twelve periods of the Phanerozoic Eon. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clypecaris
''Clypecaris'' is genus of bivalved Cambrian arthropod known from the Chengjiang biota of Yunnan, China. The genus was initially described for the type species ''C. pteroidea'' by Hou, 1999. A second species ''C. serrata'' was described by Yang et al. in 2016. The species are primarily distinguished by the presence of a serrated edge on the front of the carapace of ''C. serrata. C. serrata'' is noted for the modification of an anterior pair of limbs into spined grasping appendages, indicating a predatory lifestyle. It is unknown whether a similar structure was present in ''C. pteroidea.'' ''Clypecaris'' is considered to likely be a member or a close relative of Hymenocarina, and is closely related to '' Perspicaris''. As well as to '' Ercaicunia''. See also * Arthropod * Cambrian explosion * Chengjiang biota ** List of Chengjiang Biota species by phylum This is a list of fossils found at Maotianshan Shales, whose most famous assemblage of organisms are referred to as the Che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ercaicunia
''Ercaicunia'' is genus of bivalved Cambrian arthropod from the Chengjiang biota of Yunnan, China. It contains a single species, ''E. multinodosa'' that was described by Luo et al. in 1999. The total length of the body ranges from . The bivalved carapace covered about a third of the total body-length, and has up to six serrations on its forward edge. The head has a pair of large uniramous antennae, as well as a smaller pair of secondary antennae, as well as pair of mandibles and maxillae. The trunk has 16 pairs of biramous appendages. Specimens were CT scanned in 2019, which suggested it to be a stem-group crustacean. Other subsequent studies have recovered it as a member of Hymenocarina, which contains other bivalved Cambrian arthropods. See also * Arthropod * Cambrian explosion * Chengjiang biota ** List of Chengjiang Biota species by phylum This is a list of fossils found at Maotianshan Shales, whose most famous assemblage of organisms are referred to as the Chengjiang bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myriapoda
Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversification in the Cambrian Period, the oldest known fossil record of myriapods dates between the Late Silurian and Early Devonian, with '' Pneumodesmus'' preserving the earliest known evidence of air-breathing on land. Other early myriapod fossil species around the similar time period include '' Kampecaris obanensis'' and '' Archidesmus'' sp. The phylogenetic classification of myriapods is still debated. The scientific study of myriapods is myriapodology, and those who study myriapods are myriapodologists. Anatomy Myriapods have a single pair of antennae and, in most cases, simple eyes. Exceptions are the two classes of symphylans and pauropods, the millipede order Polydesmida and the centipede order Geophilomorpha, which are all ey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occacaris
''Occacaris'' is an extinct nektonic predatory arthropod from the Lower Cambrian Maotianshan shale Lagerstätte, known from three species. It bears a superficial resemblance to the Cambrian arthropod, ''Canadaspis'', though, was much smaller, and had a pair of "great appendages", with which it may have grasped prey. It was originally considered to belong to Megacheira, however it is questioned in later study. It had a bivalved carapace that covered most of its body, leaving only the last two tergites of its trunk, with the telson jutting out of the posterior end of the carapace, and the eyes, antennae (possibly isolated endopod), and great appendages jutting out of the anterior end. The spines of the great appendages are paired, setting it apart from '' Forfexicaris valida'' and megacheirans like '' Fortiforceps foliosa''. Suggestions have been made that ''Occacaris'' is closely related to megacheirans, or to mandibulates. See also * Arthropod * Cambrian explosion * Chengji ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parioscorpio
''Parioscorpio'' is an extinct genus of arthropod containing the species ''P. venator'' known from the Silurian-aged Waukesha Biota of the Brandon Bridge Formation near Waukesha, Wisconsin. This animal has gone through a confusing taxonomic history, being called an arachnid, crustacean, and an artiopodan arthropod at various points. This animal is one of the more famous fossil finds from Wisconsin, due to the media coverage it received based on its original description in 2020 as a basal scorpion. Taxonomy The fossils were originally discovered in 1985, tentatively identified as a branchiopod or remipede crustacean but were neglected for decades. In 2016, some of the fossils now assigned to ''Parioscorpio'' were given the name ''Latromirus'' and were assigned to an extinct group of early Paleozoic arthropods known as cheloniellids in a Ph.D dissertation, but the name was never published in a peer-reviewed journal and is therefore not valid in accordance with the International Cod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
