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Vetulocystida
Vetulocystidae is the only family of the taxon Vetulocystida, which is a group of extinct deuterostomes of uncertain phylogenetic position. Vetulocystidae is made up of the genera ''Vetulocystis'', '' Dianchicystis'' and '' Thylacocercus''. Features The body consists of a voluminous thecal-shaped section (similar to the outer shape of the pterobranchs), where there are two cone-shaped structures (anterior and posterior) and a lenticular respiratory organ; and another small section attached to the substrate. The anterior cone-shaped structure is believed to have constituted the mouth, due to its similarity to other primitive echinoderms (such as stylophoids and blastoids); while the posterior structure (similar to that of the cystoids and eocrinoids) fulfilled the functions of anus and gonopore. Furthermore, and unlike many other echinoderms, these animals lacked a calcified skeleton. Paleoecology They were probably sessile, although it is possible that the part attached to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vetulocystis
''Vetulocystis'' is an extinct genus of vetulocystids. It was found in remains of Shankou, in Anning (Cambrian of China). Approximately 541 Ma. Phylogeny See also *Vetulicola ''Vetulicola'' is an extinct genus of marine animal from the Cambrian of China. It is the eponymous member of the enigmatic phylum Vetulicolia, which is of uncertain affinities but may belong to the deuterostomes. Description The type species ... References Vetulocystidae Cambrian genus extinctions {{cambrian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vetulocystis Catenata
''Vetulocystis'' is an extinct genus of vetulocystids. It was found in remains of Shankou, in Anning (Cambrian of China). Approximately 541 Ma. Phylogeny See also *Vetulicola ''Vetulicola'' is an extinct genus of marine animal from the Cambrian of China. It is the eponymous member of the enigmatic phylum Vetulicolia, which is of uncertain affinities but may belong to the deuterostomes. Description The type species ... References Vetulocystidae Cambrian genus extinctions {{cambrian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dianchicystis
''Dianchicystis'' is an basal extinct genus of vetulocystids. It was found in Jianshan, near Haikou, Qiongzhusi Fm. (Cambrian from China). Phylogeny See also *''Haikouichthys ''Haikouichthys'' is an extinct genus of craniate (animals with notochords and distinct heads) that lived 518 million years ago, during the Cambrian explosion of multicellular life. ''Haikouichthys'' had a defined skull and other characteristic ...'' References Vetulocystidae Cambrian genus extinctions {{cambrian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccorhytus
''Saccorhytus'' (from Latin ''saccus'' "bag" and Ancient Greek ῥύτις ''rhytis'' "wrinkle") is an extinct genus of animal possibly belonging to the superphylum Ecdysozoa, and it is represented by a single species, ''Saccorhytus coronarius'' (from Latin attributive ''coronarius'' "f acrown"). The organism lived approximately 540 million years ago in the Fortunian stage of the Cambrian Period. Initially proposed as a deuterostome, which would make it the oldest known species of this superphylum, it has since been determined to belong to a group called the ecdysozoans. Fossils of the species were first discovered in the Kuanchuanpu Formation of Shaanxi province of China by a team of scientists from the United Kingdom, China and Germany, and the findings were first published in January 2017. Description ''Saccorhytus'' was only about a millimetre (1.3 mm) in size and is characterised by its globular or hemispherical body with a prominent mouth. Its body was covered b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Plan
A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprint" encompassing aspects such as symmetry, layers, segmentation, nerve, limb, and gut disposition. Evolutionary developmental biology seeks to explain the origins of diverse body plans. Body plans have historically been considered to have evolved in a flash in the Ediacaran biota; filling the Cambrian explosion with the results, and a more nuanced understanding of animal evolution suggests gradual development of body plans throughout the early Palaeozoic. Recent studies in animals and plants started to investigate whether evolutionary constraints on body plan structures can explain the presence of developmental constraints during embryogenesis such as the phenomenon referred to as phylotypic stage. History Among the pioneering zoologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filtration
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as ''oversize'' and the fluid that passes through is called the ''filtrate''. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as ''blinding''. The size of the largest particles that can successfully pass through a filter is called the effective ''pore size'' of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size, filter thickness and biological activity). Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms. Filtration is als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urochordata
A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals. They are the only chordates that have lost their myomeric segmentation, with the possible exception of the 'seriation of the gill slits'. Some tunicates live as solitary individuals, but others replicate by budding and become colonies, each unit being known as a zooid. They are marine filter feeders with a water-filled, sac-like body structure and two tubular openings, known as siphons, through which they draw in and expel water. During their respiration and feeding, they take in water through the incurrent (or inhalant) siphon and expel the filtered water through the excurrent (or exhalant) siphon. Most adult tunicates are sessile, immobile and per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vetulicolia
VetulicoliaThe taxon name, Vetulocolia, is derived from the type genus, ''Vetulicola'', which is a compound Latin word composed of ''vetuli'' "old" and ''cola'' "inhabitant". is a taxon (either phylum or subphylum in rank) encompassing several extinct Cambrian organisms. The vetulicolian body comprises two parts: a voluminous anterior forebody, tipped with an anteriorly positioned mouth and lined with a row of five round to oval-shaped features on each lateral side, which have been interpreted as gills (or at least openings in the vicinity of the pharynx); and a posterior section that primitively comprises seven segments and functions as a tail. All vetulicolians lack preserved appendages of any kind, having no legs, feelers or even eyes. The area where the anterior and posterior parts join is constricted. Their affinity has been uncertain; they have been considered to represent stem- and crown-group arthropods, stem-group vertebrates, and early deuterostomes. The general scienti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinodermata
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian. The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. Geolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homalozoa
Homalozoa is an obsolete extinct subphylum of Paleozoic era echinoderms, prehistoric marine invertebrates. They are also referred to as carpoids. Description The Homalozoa lacked the typical pentamer body form of other echinoderms, but all were sessile animals. Instead all Homalozoans were markedly asymmetric, and were extremely variable in forms. The body (theca) was covered with calcite plates with a number of openings. Their form is in some cases so unusual that it is unclear which openings are to be considered as mouth and anus. Many of them were stalked, similar to sea lilies (crinoids), but often their bodies were bent over, so that the mouth and anus projected forwards rather than upwards. Some forms, especially stylophorans, rested flat on the sea floor. In some forms the single ray ( brachiole or aulacophore) possessed an ambulacral groove. It has been claimed that some forms possessed gills and gill slits. Taxonomy Homalozoans were traditionally considered to be st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
