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Lobopods
The lobopodians, members of the informal group Lobopodia (from the Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998), 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, worm-like fossil panarthropods such as '' Aysheaia'' and ''Hallucigenia''. 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 ( Arthropoda, Tardigrada and Onychophora) are thought to have evolved from lobopodian ancestors. Definitions The Lobopodian concept varies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collinsovermis
''Collinsovermis'' is a genus of extinct panarthropod belonging to the group Lobopodia and known from the middle Cambrian Burgess Shale in British Columbia, Canada. It is monotypic having only one species, ''Collinsovermis monstruosus''. After its initial discovery in 1983, Desmond H. Collins popularised it as a unique animal and was subsequently dubbed "Collins' monster" for its unusual super armoured body. The formal scientific description and name were given in 2020. Discovery ''Collinsovermis'' was discovered in 1983 by Desmond H. Collins, curator of invertebrate palaeontology at the Royal Ontario Museum, from an expedition at Mount Stephen at the Yoho National Park, British Columbia, Canada. It was found among the Burgess Shale that belonged to the middle Cambrian period called Wuliuan, which is around 509 to 505 million years ago. In 1985, Collins presented the discovery before the Geological Society of America, and published the next year in a popular magazine ''Rotun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diania
''Diania'' is an extinct genus of lobopodian animal found in the Lower Cambrian Maotianshan shale of China, represented by a single species - ''D. cactiformis''. Known during its investigation by the nickname "walking cactus", this organism belongs to a group known as the armoured lobopodians, and has a simple worm-like body with robust, spiny legs. Initially, the legs were thought to have a jointed exoskeleton and ''Diania'' was suggested to be evolutionarily close to early arthropods, but many later studies have rejected this interpretation. Discovery Fossils of ''Diania'' were discovered independently by Jianni Liu from the Northwest University (China) in Xi’an, Qiang Ou from the China University of Geosciences in Beijing and Michael Steiner of the Free University Berlin. The fossils come from the famous Chengjiang deposit – or Maotianshan shale – of south-west China and are about 520 million years old. Specifically, they come from the Yu'anshan Formation, dated to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luolishania
''Luolishania'' is an extinct genus of lobopodian worm and known from the Lower Cambrian Chiungchussu Formation (Maotianshan Shales) of the Chengjiang County, Yunnan Province, China. A monotypic genus, it contains one species ''Luolishania longicruris''. It was discovered and described by Hou Xian-Guang and Chen Jun-Yuan in 1989. It is one of the superarmoured Cambrian lobopodians suspected to be either an intermediate form in the origin of velvet worms (Onychophora) or basal to at least Tardigrada and Arthropoda. It is the basis of the family name Luolishaniidae, which also include other related lobopods such as ''Acinocricus'', ''Collinsium'', '' Facivermis,'' and '' Ovatiovermis''. Along with '' Microdictyon'', it is the first lobopodian fossil discovered from China. Discovery A single specimen of ''Luolishania'' fossil was discovered by Hou Xian-guang and Chen Jun-yuan of the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, from the Chengjiang L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onychophora
Onychophora (from grc, ονυχής, , "claws"; and , , "to carry"), commonly known as velvet worms (due to their velvety texture and somewhat wormlike appearance) or more ambiguously as peripatus (after the first described genus, '' Peripatus''), is a phylum of elongate, soft-bodied, many-legged panarthropods. In appearance they have variously been compared to worms with legs, caterpillars, and slugs. They prey upon other invertebrates, which they catch by ejecting an adhesive slime. Approximately 200 species of velvet worms have been described, although the true number of species is likely greater. The two extant families of velvet worms are Peripatidae and Peripatopsidae. They show a peculiar distribution, with the peripatids being predominantly equatorial and tropical, while the peripatopsids are all found south of the equator. It is the only phylum within Animalia that is wholly endemic to terrestrial environments, at least among extant members. Velvet worms are generally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jianshanopodia
''Jianshanopodia decora'' is a Cambrian lobopodian. Its frontal, grasping appendages bear wedge-shaped plates. Its limbs branch, instead of being tipped with claws as many lobopods' are. It has a sediment-filled gut surrounded by serially repeated diverticulae. It is thought to have sucked up prey with its short 'trunk'. It mainly crawled on the sea floor, but could swim when necessary. Its mouth resembles those of anomalocaridids and priapulid Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility ...s. References Prehistoric protostome genera Fossil taxa described in 2006 Lobopodia {{Cambrian-animal-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hallucigenia
''Hallucigenia'' is a genus of Cambrian animal resembling worms, known from articulated fossils in Burgess Shale-type deposits in Canada and China, and from isolated spines around the world. The generic name reflects the type species' unusual appearance and eccentric history of study; when it was erected as a genus, ''H. sparsa'' was reconstructed as an enigmatic animal upside down and back to front. ''Hallucigenia'' was later recognized as a lobopodian, a grade of Paleozoic panarthropods from which the velvet worms, water bears, and arthropods arose. Description ''Hallucigenia'' is a long tubular animal with up to ten pairs of slender legs (lobopods). The first 2 or 3 leg pairs are slender and featureless, while the remaining 7 or 8 pairs each terminate with 1 or 2 claws. Above the trunk region are 7 pairs of rigid conical sclerites (spines) corresponding to the 3rd–9th leg pairs. The trunk is either featureless (''H. sparsa'') or divided by heteronomous annulation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aysheaia
''Aysheaia'' is an extinct genus of soft-bodied lobopod, known from the middle Cambrian of North America, with an average body length of 1–6 cm. 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 legs 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 Based on its association with sponge remains, it is believed that ''Aysheaia'' was a sponge grazer and may have protected itself from predators by seeking refuge within sponge colonies. ''Aysheaia'' probably used its claws to cling to sponges. A terminal mouth is also seen in tardigrades ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerygmachela
''Kerygmachela kierkegaardi'' is a gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with its relative '' Pambdelurion whittingtoni'', was a close relative of radiodont (anomalocaridids) and euarthropods. The generic name "Kerygmachela" derives from the Greek words ''Kerygma'' (proclamation) and ''Chela'' (claw), in reference to the flamboyant frontal appendages. The specific name, "kierkegaardi" honors Danish philosopher Søren Kierkegaard. Morphology The head of ''Kerygmachela'' possesses a pair of well-developed frontal appendages which correspond to those of other dinocaridids and siberiid lobopodians. Each of them terminates in a series of long spines. A pair of sessile, slit-like compound eyes is located slightly behind the base of these appendages. A small anterior-facing mouth is located below the head and bears a pair of stylet-like structures. The head also possesses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microdictyon
''Microdictyon'' is an extinct armoured worm-like animal coated with net-like scleritic plates, known from the Early Cambrian Maotianshan shale of Yunnan China and other parts of the world. ''Microdictyon'' is part of the ill-defined taxon – Lobopodia – that includes several other odd worm-like animals that resembling worm with legs, such as '' Hallucigenia'', '' Onychodictyon'', ''Cardiodictyon'', '' Luolishania'', and ''Paucipodia''. The isolated sclerites of ''Microdictyon'' are known from other Lower Cambrian deposits. ''Microdictyon'' sclerites appear to have moulted; one sclerite seems to have been preserved during ecdysis.Figured in ''Microdictyon sinicum'' (Chen, Hou and Lu, 1989) is typical. The wormlike animal has ten pairs of sclerites (suggestions that these may be eyes or eye-like structures have no weight) on the sides, matched to a pair of tentacle-like feet below. The head and posterior are tubular and featureless. Species composition *Type s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onychodictyon
''Onychodictyon'' is a genus of extinct lobopodian known from the Lower Cambrian Chengjiang Maotianshan Shales in the Yunnan Province in China. It was characterized by a stout body covered by fleshy papillae and pairs of sclerotized plates with spines, representing part of the diverse "armoured lobopodians" alongside similar forms such as ''Microdictyon'' and ''Hallucigenia''. The maximum length of ''Onychodictyon'' is . It has a resemblance to ''Microdictyon'' (net-like sclerite ornament) but also ''Aysheaia ''Aysheaia'' is an extinct genus of soft-bodied lobopod, known from the middle Cambrian of North America, with an average body length of 1–6 cm. Anatomy ''Aysheaia'' has ten body segments, each of which has a pair of spiked, annulate ...'' and tardigrade (basally-fused terminal leg pair). Each leg have a pair of curved claws that are thought to have aided ''Onychodictyon'' climb onto other organisms. ''Onychodictyon'' sclerites appear to have molted with so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic group (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term was coined by Willi Hennig to apply to well-known taxa like Reptilia ( reptiles) which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor, including all extant reptiles as well as the extinct synaps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfossils
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil. Microfossils are a common feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in brackish water, fresh water and terrestrial sedimentary deposits. While every kingdom of life is represented in the microfossil record, the most abundant forms are protist skeletons or microbial cysts from the Chrysophyta, Pyrrhophyta, Sarcodina, acritarchs and chitinozoans, together with pollen and spores from the vascular plants. Overview A microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked eye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
