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Hallucishaniids
"Hallucishaniids" are a clade of lobopodians uniting the families Hallucigeniidae and Luolishaniidae. The name of this clade is a portmanteau of its two constituent families. Morphology and description Hallucishaniids have two or three body zones. The first of these contains the eyespot-bearing head and several pairs of feathery appendages likely specialised for filter feeding. The second, larger zone consists of many pairs of clawed limbs used for walking with each pair corresponding to a sclerite, with a third zone present in '' Ovatiovermis'' where the feathery appendages continue with far shorter branches, and clawed limbs are reduced to the last few pairs. The limb claws seem to alternate which direction they face. Most hallucishaniids have spine-like sclerites which vary in width and length, however some like '' Cardiodictyon'' have more plate-like sclerites, and ''Ovatiovermis'' as well as ''Facivermis'' lack them entirely. '' Thanahita'' is especially bizarre, as wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobopodia
Lobopodians are members of the informal group Lobopodia (), or the formally erected phylum Lobopoda Cavalier-Smith (1998). They are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as well. While the definition of lobopodians may differ between literatures, it usually refers to a group of soft-bodied, marine worm-like fossil panarthropods such as '' Aysheaia'' and '' Hallucigenia''. However, other genera like '' Kerygmachela'' and '' Pambdelurion'' (which have features similar to other groups) are often referred to as “gilled lobopodians”. The oldest near-complete fossil lobopodians date to the Lower Cambrian; some are also known from Ordovician, Silurian and Carboniferous Lagerstätten. Some bear toughened claws, plates or spines, which are commonly preserved as carbonaceous or mineralized microfossils in Cambrian strata. The grouping is considered to be paraphyletic, as the three living panarthropod groups (A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tardigrade
Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them . In 1776, the Italian biologist Lazzaro Spallanzani named them Tardigrada, which means 'slow walkers'. They live in diverse regions of Earth's biospheremountaintops, the deep sea, tropical rainforests, and the Antarctic. Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions – such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation – that would quickly kill most other forms of life. Tardigrades have survived exposure to outer space. There are about 1,500 known species in the phylum Tardigrada, a part of the superphylum Ecdysozoa. The earliest known fossil is from the Cambrian, some 500 million years ago ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thanahita
''Thanahita'' is a genus of extinct lobopodian and known from the middle Silurian Herefordshire Lagerstätte at the England–Wales border in UK. It is monotypic and contains one species, ''Thanahita distos.'' Discovered in 2018, it is estimated to have lived around 430 million years ago and is the first Silurian lobopodian known worldwide. Discovery ''Thanahita'' was discovered in 2018 during a palaeontological expedition funded by the Natural Environment Research Council (NERC) and the Leverhulme Trust. The team of researchers comprised Derek J. Siveter (University of Oxford), Derek E. G. Briggs (Yale University), David J. Siveter (University of Leicester), Mark D. Sutton (Imperial College London) and David Legg (University of Manchester). The fossil was discovered from the Herefordshire Lagerstätte, which has been known to be a rich source of fossils of diverse animals. The only fossil of ''Thanahita'' (designated OUMNH C.29699) was collected from the upper part of Wenlock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burgess Shale Fossils
The fossils of the Burgess Shale, like the Burgess Shale itself, are fossils that formed around 505 million years ago in the mid-Cambrian, Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 65,000 specimens in a series of field trips up to the alpine site from 1909 to 1924. After a period of neglect from the 1930s to the early 1960s, new excavations and re-examinations of Walcott's collection continue to reveal new species, and statistical analysis suggests that additional discoveries will continue for the foreseeable future. Stephen Jay Gould's 1989 book ''Wonderful Life (book), Wonderful Life'' describes the history of discovery up to the early 1980s, although his analysis of the implications for evolution has been contested. The fossil beds are in a series of shale layers, averaging and totalling about in thickness. These layers were deposited against the face of a high undersea limestone cliff. All these features were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polychaete
Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm (''Arenicola marina'') and the Alitta virens, sandworm or Alitta succinea, clam worm ''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe Nereus (underwater vehicle), ''Nereus'' at the bottom of the Challenger Deep, the deepest known spot in the Earth's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entothyreos
''Entothyreos'' is a genus of extinct panarthropod belonging to the group Lobopodia and known from the middle Cambrian Burgess Shale in British Columbia, Canada. The genus contains a single species, ''Entothyreos synnaustrus'' (meaning "convergent inner shield"), described in 2024. ''Entothyreos'' is significant for possessing a remarkable degree of sclerotization among lobopodians, comparable to that of arthropods. Description ''Entothyreos'' is a stout collinsovermid lobopodian, capable of reaching roughly in length. The dorsum was protected by numerous paired sclerite spines (two pairs per trunk segment). The spines are longest at the middle of the body. These spines are associated (although still dissociable) with subrectangular sclerotic sheets which lie just below the cuticle surface. These sclerite sheets may have increased body rigidity, allowing easier erection of the body to allow for suspension feeding from the water column. They are comparable with the sclerotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aysheaia
''Aysheaia'' is an extinct genus of soft-bodied lobopodian, known from the Middle Cambrian Burgess Shale of British Columbia, Canada. Anatomy ''Aysheaia'' has ten body segments, each of which has a pair of spiked, annulate legs. The animal is segmented, and looks somewhat like a bloated caterpillar with a few spines added on — including six finger-like projections around the mouth and two grasping limbs on the "head". Each leg has a subterminal row of about six curved claws. No jaw apparatus is evident. A pair of legs marks the posterior end of the body, unlike in onychophorans where the anus projects posteriad; this may be an adaptation to the terrestrial habit. Ecology Some specimens of ''Aysheaia'' have been found associated with sponges, though this does not provide direct evidence of diet. Affinity ''Aysheaia'' is a lobopodian, an extinct phylum of marine animals that are similar to modern terrestrial Onychophora (velvet worms). Notable differences are the lack of ja ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collinsium
''Collinsium'' was a genus of lobopodian from the Early Cambrian. It is represented by a single fossil species, ''Collinsium ciliosum'', found in the Xiaoshiba Lagerstätte ( Hongjingshao Formation) of China. Similar to the later ''Hallucigenia'' it was a small worm-like creature with spikes along its back and feeding tentacles near its head. Unlike ''Hallucigenia'', ''Collinsium'' had 9 walking appendages and 6 fine anterior appendages. Its body was covered in hair-like papillae and its fine anterior appendages were lined with setae. The generic name honors paleontologist Desmond Collins. Description ''Collinsium'' was a small animal with complete specimens reaching 85mm in length. 15 sets of biomineralized spines lined its back. All but the first set were composed of one large medial spine, a pair of medium spines, and a pair of small lateral spines. The first six appendage pairs were long and lined with approximately 30 pairs of bristle-like setae that angled downward to fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acinocricus
''Acinocricus'' is a genus of extinct panarthropod belonging to the group Lobopodia and known from the middle Cambrian Spence Shale of Utah, United States. As a monotypic genus, it has one species ''Acinocricus stichus''. The only lobopodian discovered from the Spence Shale, it was described by Simon Conway Morris and Richard A. Robison in 1988. Owing to the original fragmentary fossils discovered since 1982, it was initially classified as an alga, but later realised to be an animal belonging to Cambrian fauna. Discovery The first specimen of ''Acinocricus'' was discovered by American palaeontologist Lloyd Gunther in 1982 from the Spence Shale in Miners Hollow, Wellsville Mountains, Utah. It was embedded in hardened mud and was incomplete with some of its body part missing. More than a dozen fragmentary fossils were later recovered from the same site and the surrounding areas. Simon Conway Morris of the University of Cambridge and Richard A. Robison of the University of Kansas j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facivermis
''Facivermis'' (meaning "torch worm" ) is a genus of sessile lobopodian from the Lower Cambrian Maotianshan shales of China Anatomy ''Facivermis'' was a worm-like creature up to 90 mm long. Its body was divided into three sections. The anterior section had five equally sized pairs of appendages with two setal rows along the margins. The middle section was elongate and five times longer than the anterior or posterior. The posterior section was pear-shaped and had three rows of hooks surrounding the anus. Classification ''Facivermis'' was considered by its describers to be a polychaete worm. An affinity to the unusual crustacean lineage Pentastomida has also been proposed, but is seen as unlikely. Since its discovery, however, most evidence has supported its being a lobopodian. Liu ''et al.'' draw a comparison to the known lobopodian '' Miraluolishania''. Liu ''et al.'' also note that the pear-shaped end bears a close resemblance to the proboscis of priapulid worms if it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
