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Blastoidea
Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period. However, blastoids may have originated in the Cambrian. Blastoids persisted until their extinction at the end of Permian, about 250 million years ago. Although never as diverse as their contemporary relatives, the crinoids, blastoids are common fossils, especially in many Mississippian-age rocks. Description Like most echinoderms, blastoids were protected by a set of interlocking plates of calcium carbonate, which formed the main body, or ''theca''. In life, the theca of a typical blastoid was attached to a stalk or column made up of stacked disc-shaped plates. The other end of the column was attached to the ocean floor by a holdfast, very much like stalked crinoids. The stalk was usually relat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blastozoa
Blastozoa is a subphylum of extinct animals belonging to Phylum Echinodermata. This subphylum is characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. This subphylum ranged from the Cambrian to the Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz .... References External linksHarvard: Subphylum 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] |
Echinoderm
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. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentremites
''Pentremites'' is an extinct genus of blastoid echinoderm belonging to the family Pentremitidae. Description These stalked echinoderms averaged a height of about but occasionally ranged up to about 3 times that size. They, like other blastoids, superficially resemble their distant relatives, the crinoids or ''sea lilies'', having a near-identical, planktivore, planktivorous lifestyle living on the sea floor attached by a stalk. As with all other blastoids, species of ''Pentremites'' trapped food floating in the currents by means of tentacle-like appendages. ''Pentremites'' species lived in the early to middle Carboniferous, from 360.7 to 314.6 Ma. Its fossils are known from North America. References * ''Fossils'' (Smithsonian Handbooks) by David Ward (paleontologist), David Ward (Page 190) Blastozoa genera Carboniferous echinoderms of North America Fossils of Georgia (U.S. state) Paleozoic life of Alberta Paleozoic life of the Northwest Territories Paleozoic life of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentremites Glen Dean Fm KY Aboral
''Pentremites'' is an extinct genus of blastoid echinoderm belonging to the family Pentremitidae. Description These stalked echinoderms averaged a height of about but occasionally ranged up to about 3 times that size. They, like other blastoids, superficially resemble their distant relatives, the crinoids or ''sea lilies'', having a near-identical, planktivorous lifestyle living on the sea floor attached by a stalk. As with all other blastoids, species of ''Pentremites'' trapped food floating in the currents by means of tentacle-like appendages. ''Pentremites'' species lived in the early to middle Carboniferous, from 360.7 to 314.6 Ma. Its fossils are known from North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car .... References * ''Fossils'' (Smithsonian Handbooks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambulacral
Ambulacral is a term typically used in the context of anatomical parts of the phylum Echinodermata or class Sea star, Asteroidea and Edrioasteroidea. Echinoderms can have ambulacral parts that include Ossicle (echinoderm), ossicles, plates, spines, and suckers. For example, sea stars or "star fish" have an ambulacral groove on their oral side (underside). This ambulacral groove extends from the mouth to the end of each ray or arm. Each groove of each arm in turn has four rows of hollow tube feet that can be extended or withdrawn. Opposite the ambulacral groove is an ambulacral ridge on the aboral side of each ray, known as an ambulacrum (anatomy), ambulacrum. These have interambulacra between them. Etymology From the Latin 'ambulācrum', meaning 'walk planted with trees', 'avenue', 'alley' and 'walking place' Derives from' 'ambulāre', meaning 'to walk' or 'Amble' meaning 'To walk slowly or leisurely'. Has Indo-European roots - deriving from 'Ambhi'The Free Dictionary (n.d.) amb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian Echinoderms
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the sauropsids (reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian Echinoderms
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician Echinoderms
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian Perio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tennessee
Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to the north, Virginia to the northeast, North Carolina to the east, Georgia, Alabama, and Mississippi to the south, Arkansas to the southwest, and Missouri to the northwest. Tennessee is geographically, culturally, and legally divided into three Grand Divisions of East, Middle, and West Tennessee. Nashville is the state's capital and largest city, and anchors its largest metropolitan area. Other major cities include Memphis, Knoxville, Chattanooga, and Clarksville. Tennessee's population as of the 2020 United States census is approximately 6.9 million. Tennessee is rooted in the Watauga Association, a 1772 frontier pact generally regarded as the first constitutional government west of the Appalachian Mountains. Its name derives from "Tanas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cystoids
Cystoidea is a class of extinct crinozoan echinoderms, termed cystoids, that lived attached to the sea floor by stalks. They existed during the Paleozoic Era, in the Middle Ordovician and Silurian Periods, until their extinction in the Devonian Period. Description Cystoids are distinguished from other echinoderms by triangular pore openings. Superficially, cystoids resembled crinoids, but they had an ovoid, rather than cup-shaped, body. The mouth was at the upper pole of the body, with the opposite end attached to the substratum, often by a stalk, although some stalkless species did exist. The anus lay on the side of the body. Five, or less commonly three, ambulacral areas ran along the outside of the body, radiating outwards from the mouth. A number of small tentacles either surrounded the mouth, or projected outwards in a row from the ambulacral areas, depending on species. The most distinctive feature of cystoids was the presence of a number of pores in the rigid skeleton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Shelf
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island is known as an ''insular shelf''. The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope, surrounded by the flatter continental rise, in which sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope. Extending as far as 500 km (310 mi) from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rise's gradient is intermediate between the gradients of the slope and the shelf. Under the United Nations Convention on the Law of the Sea, the name continental shelf was given a legal definition as the stretch of the seabed adjacent to the shores of a par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
