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Anaspida
Anaspida ("without shield") is an extinct group of primitive jawless vertebrates that lived primarily during the Silurian period, and became extinct soon after the start of the Devonian. They were classically regarded as the ancestors of lampreys. Anaspids were small marine agnathans that lacked a heavy bony shield and paired fins, but have a striking highly hypocercal tail. They first appeared in the early Silurian, and flourished until the early Devonian, when they disappear from the fossil record. Anatomy Compared to other prehistoric agnathan groups, such as the Heterostraci and Osteostraci, anaspids did not possess a bony shield or armor, hence their name. The anaspid head and body are instead covered in an array of small, weakly mineralized scales, with a row of massive scutes running down the back, and, at least confirmed among the birkeniids, the body was covered in rows of tile-like scales made of aspidine, an acellular bony tissue. Anaspids all had prominent, latera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaspida
Anaspida ("without shield") is an extinct group of primitive jawless vertebrates that lived primarily during the Silurian period, and became extinct soon after the start of the Devonian. They were classically regarded as the ancestors of lampreys. Anaspids were small marine agnathans that lacked a heavy bony shield and paired fins, but have a striking highly hypocercal tail. They first appeared in the early Silurian, and flourished until the early Devonian, when they disappear from the fossil record. Anatomy Compared to other prehistoric agnathan groups, such as the Heterostraci and Osteostraci, anaspids did not possess a bony shield or armor, hence their name. The anaspid head and body are instead covered in an array of small, weakly mineralized scales, with a row of massive scutes running down the back, and, at least confirmed among the birkeniids, the body was covered in rows of tile-like scales made of aspidine, an acellular bony tissue. Anaspids all had prominent, latera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnathan
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 are sister to all vertebrates with jaws, known as gnathostomes. Recent molecular data, both from rRNA and from mtDNA as well as embryological data, strongly supports the hypothesis that living agnathans, the cyclostomes, are monophyletic. The oldest fossil agnathans appeared in the Cambrian, and two groups still survive today: the lampreys and the hagfish, comprising about 120 species in total. Hagfish are considered members of the subphylum Vertebrata, because they secondarily lost vertebrae; before this event was inferred from molecular and developmental data, the group Craniata was created by Linnaeus (and is still sometimes used as a strictly morphological descriptor) to reference hagfish plus vertebrates. While a few scientist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnatha
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 are sister to all vertebrates with jaws, known as gnathostomes. Recent molecular data, both from rRNA and from mtDNA as well as embryological data, strongly supports the hypothesis that living agnathans, the cyclostomes, are monophyletic. The oldest fossil agnathans appeared in the Cambrian, and two groups still survive today: the lampreys and the hagfish, comprising about 120 species in total. Hagfish are considered members of the subphylum Vertebrata, because they secondarily lost vertebrae; before this event was inferred from molecular and developmental data, the group Craniata was created by Linnaeus (and is still sometimes used as a strictly morphological descriptor) to reference hagfish plus vertebrates. While a few scie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endeiolepididae
''Endeiolepis'' is an extinct jawless fish that lived during the Late Devonian period, similar to that of extant lampreys Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like su ... for its gill pouches, but ''Endeiolepis'' had an unusually large number of gill pouches. ''Endeiolepis'' was also described as being quite similar to '' Euphanerops'', the main difference being a long series of elongated scales forming a ventrolateral protuberance on each side of Endeiolepis’ body. ''Endeiolepis'' had a strongly heterocercal tail. References Discoveries of ''Endeiolepis'' External links Anaspida genera Devonian jawless fish Late Devonian fish Fossils of Canada {{Devonian-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birkeniida
Birkeniiformes (Birkeniida or Birkeniids) is an extinct order of jawless fish belonging to the class Anaspida. Subtaxa A newer taxonomy based on the work of Mikko's Phylogeny Archive, Nelson, Grande and Wilson 2016 and van der Laan 2018. * Genus †'' Cowielepis'' Blom 2008 * Genus †'' Hoburgilepis'' Blom, Märss & Miller 2002 * Genus †'' Kerreralepis'' Blom 2012 * Genus †'' Maurylepis'' Blom, Märss & Miller 2002 * Genus †'' Rytidolepis'' Pander 1856 * Genus †'' Schidiosteus'' Pander 1856 * Genus †'' Silmalepis'' Blom, Märss & Miller 2002 * Genus †'' Vesikulepis'' Blom, Märss & Miller 2002 * Family † Pharyngolepididae Kiær 1924 corrig. ** Genus †'' Pharyngolepis'' Kiaer 1911 * Family † Pterygolepididae Obručhev 1964 corrig. ** Genus †'' Pterygolepis'' Cossmann 1920 'Pterolepis'' Kiaer 1911 non Rambur 1838 non De Candolle ex Miquel 1840; ''Pterolepidops'' Fowler 1947 * Family † Rhyncholepididae Kiær 1924 corrig. ** Genus †''Rhyncholepis'' Kiær 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birkeniids
Birkeniiformes (Birkeniida or Birkeniids) is an extinct order of jawless fish belonging to the class Anaspida. Subtaxa A newer taxonomy based on the work of Mikko's Phylogeny Archive, Nelson, Grande and Wilson 2016 and van der Laan 2018. * Genus †'' Cowielepis'' Blom 2008 * Genus †'' Hoburgilepis'' Blom, Märss & Miller 2002 * Genus †'' Kerreralepis'' Blom 2012 * Genus †'' Maurylepis'' Blom, Märss & Miller 2002 * Genus †'' Rytidolepis'' Pander 1856 * Genus †'' Schidiosteus'' Pander 1856 * Genus †'' Silmalepis'' Blom, Märss & Miller 2002 * Genus †'' Vesikulepis'' Blom, Märss & Miller 2002 * Family † Pharyngolepididae Kiær 1924 corrig. ** Genus †'' Pharyngolepis'' Kiaer 1911 * Family † Pterygolepididae Obručhev 1964 corrig. ** Genus †'' Pterygolepis'' Cossmann 1920 'Pterolepis'' Kiaer 1911 non Rambur 1838 non De Candolle ex Miquel 1840; ''Pterolepidops'' Fowler 1947 * Family † Rhyncholepididae Kiær 1924 corrig. ** Genus †''Rhyncholepis'' Kiær 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cowielepis
''Cowielepis'' is an extinct genus of jawless fish in the class Anaspida. It is from the middle Silurian Cowie Harbour fish bed of Stonehaven, Scotland. Habits It was possibly a nectonic filter, of active locomotion, due to its physiognomy. Distribution Lochkovian of United Kingdom (Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...). References External links * Birkeniiformes genera Fossil taxa described in 2008 {{paleo-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birkeniiformes
Birkeniiformes (Birkeniida or Birkeniids) is an extinct order of jawless fish belonging to the class Anaspida. Subtaxa A newer taxonomy based on the work of Mikko's Phylogeny Archive, Nelson, Grande and Wilson 2016 and van der Laan 2018. * Genus †''Cowielepis'' Blom 2008 * Genus †'' Hoburgilepis'' Blom, Märss & Miller 2002 * Genus †'' Kerreralepis'' Blom 2012 * Genus †'' Maurylepis'' Blom, Märss & Miller 2002 * Genus †'' Rytidolepis'' Pander 1856 * Genus †'' Schidiosteus'' Pander 1856 * Genus †'' Silmalepis'' Blom, Märss & Miller 2002 * Genus †'' Vesikulepis'' Blom, Märss & Miller 2002 * Family † Pharyngolepididae Kiær 1924 corrig. ** Genus †'' Pharyngolepis'' Kiaer 1911 * Family † Pterygolepididae Obručhev 1964 corrig. ** Genus †'' Pterygolepis'' Cossmann 1920 'Pterolepis'' Kiaer 1911 non Rambur 1838 non De Candolle ex Miquel 1840; ''Pterolepidops'' Fowler 1947 * Family † Rhyncholepididae Kiær 1924 corrig. ** Genus †''Rhyncholepis'' Kiær 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endeiolepidiformes
''Endeiolepis'' is an extinct jawless fish that lived during the Late Devonian period, similar to that of extant lampreys Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like s ... for its gill pouches, but ''Endeiolepis'' had an unusually large number of gill pouches. ''Endeiolepis'' was also described as being quite similar to '' Euphanerops'', the main difference being a long series of elongated scales forming a ventrolateral protuberance on each side of Endeiolepis’ body. ''Endeiolepis'' had a strongly heterocercal tail. References Discoveries of ''Endeiolepis'' External links Anaspida genera Devonian jawless fish Late Devonian fish Fossils of Canada {{Devonian-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jamoytiiformes
Jamoytiiformes is an extinct order of prehistoric jawless fish in the superclass Anaspidomorphi. Taxonomy Taxonomy is based on Mikko's Phylogeny Archive * Family † Achanarellidae Newman 2002 ** Genus †'' Achanarella'' Newman 2002 'Achanarella'' Saxon 1978 nomen nudum*** †'' Achanarella trewini'' Newman 2002 * Family † Jamoytiidae White 1946 ** Genus †'' Conopiscius'' Briggs & Clarkson 1987 *** †'' Conopiscius clarki'' Briggs & Clarkson 1987 ** Genus †''Jamoytius ''Jamoytius kerwoodi'' was a species of primitive, eel-like jawless fish that lived in the Llandovery epoch of the Early Silurian period. Long thought of as a "basal anaspid," ''J. kerwoodi'' is now recognized as the best-known member of the H ...'' White 1946 *** †'' Jamoytius kerwoodi'' White 1946 References * A New Interpretation of Jamoytius Kerwoodi White. Alexander Ritchie, Nature, volume 188, pages 647–649 (19 November 1960), External links Prehistoric jawless fish orders [...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] |
Birkenia Elegans
''Birkenia'' is a genus of extinct anaspid fish from Middle Silurian strata of Northern Europe, and Middle Silurian to possibly Earliest Devonian strata of Arctic Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ....Blom, Henning, T. Märss, and C. G. Miller. "Silurian and earliest Devonian birkeniid anaspids from the Northern Hemisphere." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 92.03 (2001): 263-323/ref> Birkeniid anaspids are covered by a series of small plates on the head and rod-shaped scales in a cheveron-like pattern on the trunk. Intact fossil specimens of ''B. elegans'' suggest the living animal reached a length of up to , and was an active swimmer. In addition to whole specimens and scale microfossils of ''B. elegans'', which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
