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Angarichthys
''Angarichthys hyperboreus'' is an extinct homostiid arthrodire placoderm from the Middle Devonian (either upper Eifelian or lower Givetian) of Siberia. It is known from an infragnathal plate, an intero-lateral plate, and a marginal plate found from the Middle Devonian strata of the Tynep Series formation, in the Bakhta River basin, Tunguska Plateau The Tunguska Plateau ( rus, Тунгусское плато) is a mountain plateau in Krasnoyarsk Krai, Siberia, Russia. It is a part of the Central Siberian Plateau. The plateau is located in largely uninhabited area, the village of Noginsk wa .... ''A. hyperboreus'' differs from ''Homosteus'' in that the former's marginal plate has a ridge where the central plate would have overlapped it, and in the infragnathal, which is curved sigmoidally, and bears at least seven tooth-like prongs nearer to the functional anterior end (the plate, which is fragmentary, suggests that the intact plate would have born several more). The living ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homostiid
Homostiidae is a family of flattened arthrodire placoderms from the Early to Middle Devonian. Fossils appear in various strata in Europe, Russia, Morocco, Australia, Canada and Greenland. Many homostiids have " toothless" jaws, and large sizes. suggesting that many homostiids were probably filter feeders, like the also noticeably flattened Rhincodon typus. All homostiids have flattened and elongated skulls. According to Denison 1978, primitive homostiids have moderately long median dorsal plates, whereas in "advanced" homostiids, the median dorsal tends to be short and broad. Obruchev (1964) placed the following primitive genera ''Euleptaspis'', ''Lophostracon'' and ''Luetkeichthys'' in a separate family, "Euleptaspididae," and Ørvig (1969), claimed that the Euleptaspidids were totally unrelated to Homostiidae proper (i.e., being neither related to, nor ancestral), but, according to Denison, did not clearly explain his reasons why this was so. Genera ''Angarichthys'' A com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homostiidae
Homostiidae is a family of flattened arthrodire placoderms from the Early to Middle Devonian. Fossils appear in various strata in Europe, Russia, Morocco, Australia, Canada and Greenland. Many homostiids have " toothless" jaws, and large sizes. suggesting that many homostiids were probably filter feeders, like the also noticeably flattened Rhincodon typus. All homostiids have flattened and elongated skulls. According to Denison 1978, primitive homostiids have moderately long median dorsal plates, whereas in "advanced" homostiids, the median dorsal tends to be short and broad. Obruchev (1964) placed the following primitive genera ''Euleptaspis'', ''Lophostracon'' and ''Luetkeichthys'' in a separate family, "Euleptaspididae," and Ørvig (1969), claimed that the Euleptaspidids were totally unrelated to Homostiidae proper (i.e., being neither related to, nor ancestral), but, according to Denison, did not clearly explain his reasons why this was so. Genera ''Angarichthys'' A comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
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 domina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordata
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name “chordate” comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate structure and movement. Chordates are also bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit metameric segmentation. In addition to the morphological characteristics used to define chordates, analysis of genome sequences has identified two conserved signature indels (CSIs) in their proteins: cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cephalochordates. These CSIs provi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placodermi
Placodermi (from Greek πλάξ 'plate' and δέρμα 'skin', literally ' plate-skinned') is a class of armoured prehistoric fish, known from fossils, which lived from the Silurian to the end of the Devonian period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were among the first jawed fish; their jaws likely evolved from the first of their gill arches. Placoderms are thought to be paraphyletic, consisting of several distinct outgroups or sister taxa to all living jawed vertebrates, which originated among their ranks. In contrast, one 2016 analysis concluded that placodermi are likely monophyletic, though these analyses have been further dismissed with more transitional taxa between placoderms and modern gnathosthomes, solidifying their paraphyletic status. Placoderms were also the first fish to develop pelvic fins, the precursor to hindlimbs in tetrapods, as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthrodira
Arthrodira (Greek for "jointed neck") is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of Placoderms. Description Arthrodire placoderms are notable for the movable joint between armor surrounding their heads and bodies. Like all placoderms, they lacked distinct teeth; instead, they used the sharpened edges of a bony plate on their jawbone as a biting surface. The eye sockets are protected by a bony ring, a feature shared by birds and some ichthyosaurs. Early arthrodires, such as the genus '' Arctolepis'', were well-armoured fishes with flattened bodies. The largest member of this group, '' Dunkleosteus'', was a true superpredator of the latest Devonian period, reaching as much as 6 m in length. In contrast, the long-nosed '' Rolfosteus'' measured j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthrodire
Arthrodira (Greek for "jointed neck") is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of Placoderms. Description Arthrodire placoderms are notable for the movable joint between armor surrounding their heads and bodies. Like all placoderms, they lacked distinct teeth; instead, they used the sharpened edges of a bony plate on their jawbone as a biting surface. The eye sockets are protected by a bony ring, a feature shared by birds and some ichthyosaurs. Early arthrodires, such as the genus '' Arctolepis'', were well-armoured fishes with flattened bodies. The largest member of this group, '' Dunkleosteus'', was a true superpredator of the latest Devonian period, reaching as much as 6 m in length. In contrast, the long-nosed '' Rolfosteus'' measur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eifelian
The Eifelian is the first of two faunal stages in the Middle Devonian Epoch. It lasted from 393.3 ± 1.2 million years ago to 387.7 ± 0.8 million years ago. It was preceded by the Emsian Stage and followed by the Givetian Stage. North American subdivisions of the Eifelian Stage include Southwood, and part of Cazenovia (or Cazenovian). Name and definition The Eifelian is named after the Eifel Mountains of Western Germany, which exposed the GSSP section at the Wetteldorf Richtschnitt outcrop. The base of the Eifelian is defined by the start of the '' Polygnathus partitus'' conodont zone. This layer lies within the Upper Heisdorf Formation, below the base of the Lauch Formation. Extinctions The end of the Eifelian was marked by a biological crisis known as the Kačák Event, a two-part interval of extinction which led to ecological turnover among ammonoids, conodonts, and other free-swimming animals. In deep marine waters, the event is indicated by anoxic black shales. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Givetian
The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in France. The oldest forests occurred during the late Givetian. The lower GSSP is located at Jebel Mech Irdane Jabal, Jabel, Jebel or Jibal may refer to: People * Jabal (name), a male Arabic given name * Jabal (Bible), mentioned in the Hebrew Bible Places In Arabic, ''jabal'' or ''jebel'' (spelling variants of the same word) means 'mountain'. * Dzhebel, ..., Tafilalt, Morocco. Name and definition The Givetian Stage was proposed in 1879 by French geologist Jules Gosselet and was accepted for the higher stage of the Middle Devonian by the Subcommission on Devonian Stratigraphy in 1981. References Further reading * {{Geological history, p, p Givetian, Middle Devonian Devonian geochronology Devonian Europe, . Devonian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of Russia since the latter half of the 16th century, after the Russians conquered lands east of the Ural Mountains. Siberia is vast and sparsely populated, covering an area of over , but home to merely one-fifth of Russia's population. Novosibirsk, Krasnoyarsk and Omsk are the largest cities in the region. Because Siberia is a geographic and historic region and not a political entity, there is no single precise definition of its territorial borders. Traditionally, Siberia extends eastwards from the Ural Mountains to the Pacific Ocean, and includes most of the drainage basin of the Arctic Ocean. The river Yenisey divides Siberia into two parts, Western and Eastern. Siberia stretches southwards from the Arctic Ocean to the hills of nort ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
