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Asteracanthus
''Asteracanthus'' (from el, ἀστήρ , 'star' and el, ἄκανθα , 'spine') is an extinct genus of hybodontiform, known from the Middle Jurassic (Bathonian) to the Early Cretaceous (Valanginian). Description Astercanthus was among the largest known hybodontiformes, reaching a length of 2-3 metres. The dentition of ''Astercanthus'' is high crowned and multicusped. Fossil records This genus has been reported from the Middle Triassic to the Cretaceous, though the genus as currently circumscribed dates from the Bathonian-Valanginian, predominantly of Europe. Fossils are found in the marine strata of United States, Iran, Switzerland, Madagascar, Morocco and Europe. A complete skeleton was described in 2021 from the Late Jurassic (Tithonian) aged Solnhofen Limestone. Previously considered synonymous, the genus ''Strophodus'' (Middle Triassic-Late Cretaceous) is now considered distinct, with the teeth of ''Asteracanthus'' having more in common with ''Hybodus'' and '' Egerton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteracanthus Jaws
''Asteracanthus'' (from el, ἀστήρ , 'star' and el, ἄκανθα , 'spine') is an extinct genus of hybodontiform, known from the Middle Jurassic (Bathonian) to the Early Cretaceous (Valanginian). Description Astercanthus was among the largest known hybodontiformes, reaching a length of 2-3 metres. The dentition of ''Astercanthus'' is high crowned and multicusped. Fossil records This genus has been reported from the Middle Triassic to the Cretaceous, though the genus as currently circumscribed dates from the Bathonian-Valanginian, predominantly of Europe. Fossils are found in the marine strata of United States, Iran, Switzerland, Madagascar, Morocco and Europe. A complete skeleton was described in 2021 from the Late Jurassic (Tithonian) aged Solnhofen Limestone. Previously considered synonymous, the genus ''Strophodus'' (Middle Triassic-Late Cretaceous) is now considered distinct, with the teeth of ''Asteracanthus'' having more in common with ''Hybodus'' and '' Egerton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodontiformes
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like chondrichthyans, which existed from the late Devonian to the Late Cretaceous. They form the group of Elasmobranchii closest to neoselachians, the clade of modern sharks and rays. Hybodonts were named and are distinguished based on their conical tooth shape. They are also noted for the presence of a spine on each of their two dorsal fins. They were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct. Etymology The term hybodont comes from the Greek word ''ὕβος'' or ''ὑβός'' meaning hump or hump-backed and ''ὀδούς, ὀδοντ'' meaning tooth. This name was given based on their conical compres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodontiformes
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like chondrichthyans, which existed from the late Devonian to the Late Cretaceous. They form the group of Elasmobranchii closest to neoselachians, the clade of modern sharks and rays. Hybodonts were named and are distinguished based on their conical tooth shape. They are also noted for the presence of a spine on each of their two dorsal fins. They were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct. Etymology The term hybodont comes from the Greek word ''ὕβος'' or ''ὑβός'' meaning hump or hump-backed and ''ὀδούς, ὀδοντ'' meaning tooth. This name was given based on their conical compres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodus
''Hybodus'' (from el, ύβος , 'crooked' and el, ὀδούς 'tooth') is an extinct genus of hybodont, a group of shark-like elasmobranchs that lived from the Late Devonian to the end of the Cretaceous. Species closely related to the type species ''Hybodus reticulatus'' lived during the Early Jurassic epoch. Numerous species have been assigned to ''Hybodus'' spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination. The first fossilized teeth from ''Hybodus'' were found in England around 1845; since then teeth (and dorsal spines) have been recovered from Europe. During the Triassic, Jurassic, and Cretaceous periods, the hybodonts were especially successful and could be found in shallow seas around the world. For reasons that are not fully understood, the hybodonts became extinct near the end of the Late Cretaceous period. Description ''Hybodus'' species grew to about in length. It was not ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strophodus
''Strophodus'' is an extinct genus of hybodonts known from the Triassic to Cretaceous. It has heavily rounded, durophagous teeth. It has long been confused with ''Asteracanthus'' due to the fin spines of the latter being found associated with the teeth of ''Strophodus.'' However, both genera can now be reliably be distinguished base on the morphology of both the fin spines and teeth. Species After * ''S. reticulatus'' Agassiz, 1838 Middle-Late Jurassic (Bathonian–Tithonian) England, France, Germany, Hungary and Switzerland. A similar form ''S. cf. reticulatus'' is known from the Middle Triassic of Switzerland * ''S. smithwoodwardi'' (Peyer, 1946) Early Jurassic (Toarcian) Switzerland * ''S. dunaii'' (Szabó & Főzy (2020) Middle Jurassic (Aalenian), Hungary * ''S. tenuis'' Agassiz, 1838 Middle Jurassic (Aalenian-Bathonian) Germany, England * ''S. longidens'' Agassiz, 1838 Middle Jurassic (Bathonian) France * ''S. magnus'' Agassiz, 1838 Middle Jurassic (Bathonian) France, Ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louis Agassiz
Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he received a PhD at Erlangen and a medical degree in Munich. After studying with Georges Cuvier and Alexander von Humboldt in Paris, Agassiz was appointed professor of natural history at the University of Neuchâtel. He emigrated to the United States in 1847 after visiting Harvard University. He went on to become professor of zoology and geology at Harvard, to head its Lawrence Scientific School, and to found its Museum of Comparative Zoology. Agassiz is known for observational data gathering and analysis. He made institutional and scientific contributions to zoology, geology, and related areas, including multivolume research books running to thousands of pages. He is particularly known for his contributions to ichthyological classification, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian Fish Of North America
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] |
Prehistoric Shark Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous Sharks
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic Sharks
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triassic Sharks
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic. The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of archosaurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian Sharks
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] |
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