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Auchenaspis
''Auchenaspis salteri'' is an extinct species of armored jawless fish of the order Thyestiida from the Late Silurian of England. In England, ''A. salteri'''s fossils are found in extreme abundance in the Lower Old Red Sandstone strata in Ledbury, Herefordshire. ''A. salteri'' strongly resembles the thyestiids ''Procephalaspis'' and ''Thyestes'', and within Thyestiida, it represents a transitional form between the primitive, superficially ''Cephalaspis''-like forms, such as ''Thyestes'', and the more specialized tremataspid thyestiids, like ''Tremataspis'', ''Dartmuthia ''Dartmuthia'' is an extinct genus of primitive jawless fish that lived in the Silurian period. Fossils of ''Dartmuthia'' have been found in Himmiste Quarry, on the island of Saaremaa in Estonia Estonia, formally the Republic of Estonia, ...'', or '' Dobraspis'', whose headshields tend to resemble hot buns or horseshoe crabs. References Osteostraci genera Silurian fish of Europe Fossils of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyestiida
Thyestiida is an order of bony-armored jawless fish in the extinct vertebrate class Osteostraci The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, ....The origin and early evolution of the Osteostraci (Vertebrata): A phylogeny for the Thyestiida. Robert S. Sansom, Journal of Systematic Palaeontology, Volume 6, Issue 3, 2008, pages 317-332, References External links Thyestiidaat fossilworks.org (retrieved 21 April 2016) Osteostraci Prehistoric jawless fish orders {{Paleo-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyestes (fish)
''Thyestes'' is an extinct genus of osteostracan agnathan vertebrate of Europe whose fossils are found in Middle to Late Ludlow-aged marine strata of Late Silurian Europe. Individuals of ''Thyestes'' superficially resembled ''Cephalaspis ''Cephalaspis'' (from el, κεφαλή , 'head' and el, ἀσπίς , 'shield') is a possibly monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in the early Devonian. Description L ...'', but were more closely related to '' Auchenaspis'' and '' Tremataspis''. References Osteostraci genera Silurian fish of Europe {{silurian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteostraci Genera
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteostraci
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Museum Of Natural History (France)
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7.1 million visitors, it was the list of most visited museums, eighteenth most visited museum in the world and the second most visited natural history museum in the world after the Natural History Museum, London, Natural History Museum in London."The World's most popular museums", CNN.com, 22 June 2017. Opened in 1910, the museum on the National Mall was one of the first Smithsonian buildings constructed exclusively to hold the national collections and research facilities. The main building has an overall area of with of exhibition and public space and houses over 1,000 employees. The museum's collections contain over 145 million specimens of plants, animals, fossils, minerals, rock (geology), rocks, meteorites, human remains, and human c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dartmuthia
''Dartmuthia'' is an extinct genus of primitive jawless fish that lived in the Silurian period. Fossils of ''Dartmuthia'' have been found in Himmiste Quarry, on the island of Saaremaa in Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a .... It was first described by William Patten. ''Dartmuthia'' is one of the only osteostracans in which material of the trunk and tail behind the armored head shield have been found. Since the mouth is positioned on the underside of the head ''Dartmuthia'' is presumed to have dwelled on the ocean floor, sucking its food into its mouth. References Osteostraci genera Fauna of Estonia Silurian fish of Europe {{silurian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tremataspis
''Tremataspis'' is a genus of an extinct osteostracan agnathan from the Silurian period of what is now Estonia. ''Tremataspis'' was about in length, and had an armored shield covering its head. Compared with its relatives, the shield was unusually elongated, covering the whole front of the body, and was more rounded in shape. It is thought that ''Tremataspis'' used its rounder shield to burrow in the ocean floor, searching for food. Because the shield consisted of one solid piece, it probably did not grow during the animal's life; presumably, the larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...e lacked the shield, which only appeared later in life. References Osteostraci genera Fauna of Estonia Silurian fish of Europe {{silurian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalaspis
''Cephalaspis'' (from el, κεφαλή , 'head' and el, ἀσπίς , 'shield') is a possibly monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in the early Devonian. Description Like its relatives, ''Cephalaspis'' was heavily armored, presumedly to defend against predatory placoderms and eurypterids, as well as to serve as a source of calcium for metabolic functions in calcium-poor freshwater environments. It had sensory patches along the rim and center of its head shield, which were used to sense for worms and other burrowing organisms in the mud. Diet Because its mouth was situated directly beneath its head, ''Cephalaspis'' was thought of as being a bottom-feeder, akin to a heavily armoured catfish or sturgeon. It moved its plow-like head from side to side, ''Cephalaspis'' easily stirring sand and dust into the water, along with revealing the hiding places of its prey, digging up worms or crustaceans hidden in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herefordshire
Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthshire and Powys to the west. Hereford, the county town of Herefordshire has a population of approximately 61,000, making it the largest settlement in the county. The next biggest town is Leominster and then Ross-on-Wye. The county is situated in the historic Welsh Marches, Herefordshire is one of the most rural and sparsely populated counties in England, with a population density of 82/km2 (212/sq mi), and a 2021 population of 187,100 – the fourth-smallest of any ceremonial county in England. The land use is mostly agricultural and the county is well known for its fruit and cider production, and for the Hereford cattle breed. Constitution From 1974 to 1998, Herefordshire was part of the former non-metropolitan county of Hereford and Wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procephalaspis
''Procephalaspis'' is an extinct genus of jawless fish Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes .... References * Telling the Evolutionary Time: Molecular Clocks and the Fossil Record (Systematics Association Special Volume) by Philip C J Donoghue and M. Paul Smith (page 227) Osteostraci genera Silurian jawless fish {{silurian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods (myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
