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Eocrinoidea
The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian. The earliest genera had a short holdfast (biology), holdfast and irregularly structured plates. Later forms had a fully developed stalk with regular rows of plates. They were benthic suspension feeders, with five ambulacra on the upper surface, surrounding the mouth and extending into a number of narrow arms. Phylogeny Eocrinoids were a paraphyletic group that are seen as the basal stock from which all other blastozoan groups evolved. Early evolution The following cladogram, after Nardin et al. 2017, shows the progression of early eocrinoid families, with all other eocrinoid families (including representatives ''Trachelocrinus'' and ''Ridersia'') grouped with "derived Blastozoans" as their relationships with each other and with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinoderm
An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as larvae, as adults echinoderms are recognisable by their usually five-pointed radial symmetry (pentamerous symmetry), and are found on the sea bed at every ocean depth from the intertidal zone to the abyssal zone. The phylum contains about 7,600 living species, making it the second-largest group of deuterostomes after the chordates, as well as the largest marine-only phylum. The first definitive echinoderms appeared near the start of the Cambrian. Echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyracystis
''Lyracystis radiata'' is an extinct genus of Cambrian eocrinoid echinoderm, fossils of which are known from the Burgess Shale of British Columbia, Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun .... It is related to '' Gogia''. References External links * Burgess Shale animals Blastozoa genera Cambrian genus extinctions {{paleo-echinoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gogia
''Gogia'' is a genus of primitive eocrinoid blastozoan from the early to middle Cambrian. ''G. ojenai'' dates to the late Early Cambrian; other species come from various Middle Cambrian strata throughout North America, but the genus has yet to be described outside this continent. Notable localities where species are found include the Wheeler Shale of Utah, and the Burgess Shale of British Columbia. The species of ''Gogia'', like other eocrinoids, were not closely related to the true crinoids, instead, being more closely related to the blastoids. ''Gogia'' is distinguished from sea lilies, and most other blastoids, in that the plate-covered body was shaped like a vase, or a bowling pin (with the pin part stuck into the substrate), and that the five ambulacra were split into pairs of coiled or straight, ribbon-like strands. Six specimens of ''Gogia'' are known from the Greater Phyllopod bed The Phyllopod bed, designated by USNM locality number 35k, is the most famous foss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holdfast (biology)
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. Holdfasts vary in shape and form depending on both the species and the substrate type. The holdfasts of organisms that live in muddy substrates often have complex tangles of root-like growths. These projections are called haptera and similar structures of the same name are found on lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...s. The holdfasts of organisms that live in sandy substrates are bulb-like and very flexible, such as those of sea pens, thus permitting the organism to pull the entire body into the substrate when the holdfast is contracted. The holdfasts of organisms that liv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crinoidea
Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths of over . Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have a short ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blastozoa
Blastozoa is a subphylum of extinct echinoderms characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. It ranged from the Cambrian to the Permian. Biserial, triradiate, and pentaradiate ambulacral patterns have been identified in blastozoa specimens. The pentaradiate pattern in particular has been associated with several different classes. A significant species has been found at the Zaouïa Formation. References External linksHarvard: Subphylum Blastozoa Blastozoa, Paleozoic echinoderms Cambrian echinoderms Silurian echinoderms Ordovician echinoderms Devonian echinoderms Permian echinoderms Animal subphyla {{paleo-echinoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diploporita
Diploporita is an extinct group of blastozoans that ranged from the Ordovician to the Devonian. These echinoderms are identified by a specialized respiratory structure, called diplopores. Diplopores are a double pore system that sit within a depression on a single thecal (body) plate; each plate can contain numerous diplopore pairs. Taxonomy While once considered to be a formal class, the diploporitans likely represent a polyphyletic group. The evidence for this claim lies within the highly morphologically diverse body plans of the diploporitans: there are major differences in the makeup of the attachment structure (e.g., stem or holdfast), in the makeup of the feeding grooves, and even major differences in the construction of the group-defining diplopore respiratory structures. As of 2019 the only available phylogenetic analysis of Diploporita to date indicates that Diploporita is not a natural evolutionary group. Rather, it is an artificial grouping based on the presence of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocrinidae
The Eocrinidae are a family of early echinoderms that contain the genus ''Gogia ''Gogia'' is a genus of primitive eocrinoid blastozoan from the early to middle Cambrian. ''G. ojenai'' dates to the late Early Cambrian; other species come from various Middle Cambrian strata throughout North America, but the genus has yet t ...''. References Goggida Blastozoa Prehistoric echinoderm families Cambrian first appearances Cambrian extinctions {{paleo-echinoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibrachicystis
''Dibrachicystis'' is an extinct genus of rhombiferan echinoderm from the early Middle Cambrian (Miaolingian, Wuliuan, about 510 Ma). It is a stalked echinoderm within the family Dibrachicystidae which lived in what is now northernmost Iberian Chains, northern Spain. It is known from the holotype MPZ2009/1230 and from the paratypes MPZ2011/2–6. It was found in the uppermost part of the Murero Formation at Purujosa, Moncayo Natural Park, dating to the Lower Languedocian and referred to the ''Solenopleuropsis thorali'' Zone. It was first named by Samuel Zamora and A. B. Smith in 2011 and the type species is ''Dibrachicystis purujoensis''. Phylogeny Cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ... after Zamora & Smith, 2011 (all genera not part of a named bracket a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic Echinoderms
The Paleozoic ( , , ; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six geologic periods (from oldest to youngest), Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Some geological timescales divide the Paleozoic informally into early and late sub-eras: the Early Paleozoic consisting of the Cambrian, Ordovician and Silurian; the Late Paleozoic consisting of the Devonian, Carboniferous and Permian. The name ''Paleozoic'' was first used by Adam Sedgwick (1785–1873) in 1838 to describe the Cambrian and Ordovician periods. It was redefined by John Phillips (1800–1874) in 1840 to cover the Cambrian to Permian periods. It is derived from the Greek ''palaiós'' (παλαιός, "old") and ''zōḗ'' (ζωή, "life") meaning "ancient lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aethocrinus
''Aethocrinus'' is an early-diverging crinoid reported from the Early Ordovician. Its five arms bifurcate. The contested '' Echmatocrinus '' notwithstanding, it is a candidate for the earliest true member of the crinoid class – though not being a member of the crown group, quite where within the stem group to draw the distinction between eocrinoids and crinoids is a somewhat arbitrary decision. References Crinoidea {{Crinoidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
