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Acaenoplax
''Acaenoplax'' is an extinct worm-shaped mollusc known from the Coalbrookdale Formation of Herefordshire, England. It lived in the 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 Paleozo ... period. It was a couple of centimetres long and half a centimetre wide, and comprises serially repeated units with seven or eight shells, and rings of 'spines'. Some of its characters are reminiscent of the polychaete worms, and the character combinations do not place it obviously in the stem of any modern mollusc group, but although it was originally interpreted as a polychaete, this position is untenable for a number of reasons. Morphology The organism resembles a bristled worm, but bears a number of shells on its upper surface. The first shell is cap-like, whereas the others are saddl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kulindroplax
''Kulindroplax perissokomos'' is a Silurian mollusk, known from a single fossil from the Coalbrookdale Formation fauna of England. It lived during the Homerian Age (about 425 million years ago). It is considered a basal aplacophoran. Unlike all modern aplacophorans, which are shell-less, ''Kulindroplax'' has a chiton-like shell, and it is considered a transitional fossil in the evolution of molluscs. The only known specimen, described in 2012, was conserved at the Oxford University Museum of Natural History. Morphology ''Kulindroplax'' is about wide and long. It is the first known mollusk showing an unambiguous combination of valves, or exterior shells, and a worm-like body. It bears seven similar, unarticulated valves, with a shorter head valve and a taller caudal one, lacking ornaments and also several densely packed, long spicules. It has no discernible foot, and the radula is not preserved. A gill array is present, along with a respiratory cavity opening posteriorly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalbrookdale Formation
Coalbrookdale Formation, earlier known as Wenlock Shale or Wenlock Shale Formation and also referred to as Herefordshire Lagerstätte in palaeontology, is a fossil-rich deposit ('' Konservat-Lagerstätte'') in Powys and Herefordshire at the England–Wales border in UK. It belongs to the Wenlock Series of the Silurian Period within the Homerian Age (about 430 million years ago). It is known for its well-preserved fossils of various invertebrate animals many of which are in their three-dimensional structures. Some of the fossils are regarded as earliest evidences and evolutionary origin of some of the major groups of modern animals. Roderick Murchison first described the geological setting of Coalbrookdale Formation by which he gave the name Silurian in 1935, referring to the Silures, a Celtic tribe of Wales. It is assigned to the Wenlock Group in 1978 based on the age of crustacean fossils found around the region. Robert J. King of the University of Leicester discovered the fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heloplax
''Heloplax'' is a genus of worm-like molluscs. Its soft parts are preserved in three dimensions in the 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 Paleozo ... Herefordshire Lagerstatte; its disarticulated valves are known from other Silurian deposits. It is very bizarre by modern standards; it bears serially repeated units, and has spines. It probably falls somewhere between the aplacophorans and polyplacophora; its valves were composed of aragonite References Prehistoric chiton genera Wenlock series fossils {{Chiton-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods ... [...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] |
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] |
Polychaete Worm
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm (''Arenicola marina'') and the sandworm or clam worm ''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe ''Nereus'' at the bottom of the Challenger Deep, the deepest known spot in the Earth's oceans. Only 168 species (less than 2% of all polychaetes) are known from fresh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian Molluscs
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 glomeromycota Glomeromycota (often referred to as glomeromycetes, as they include only one class, Glomeromycetes) are one of eight currently recognized divisions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
