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Cretodus Crassidens
''Cretodus'' is an extinct genus of large mackerel sharks belonging to the proposed family Pseudoscapanorhynchidae. ''Cretodus'' lived during the Late Cretaceous, ranging from the CenomanianCicimurri, D. J. (2001). "Fossil selachians from the Belle Fourche Shale (Cretaceous, Cenomanian), Black Hills region of South Dakota and Wyoming." ''Mountain Geologist,'' 38:181-192. to the ConiacianHamm S.A. & Cicimurri D. J. (2011). "Early Coniacian (Late Cretaceous) selachian fauna from the basal Atco Formation, lower Austin Group, north central Texas." ''Paludicola'', 8(3): 107-127. (approximately 100 to 89 million years ago). The genus is well-known from strata deposited in the Western Interior Seaway (North America), and from the Late Cretaceous of Europe, Africa, and possibly Asia. ''Cretodus'' is primarily represented in the fossil record by isolated teeth and vertebral centra, though a couple of associated dentitions and vertebral columns have been found. Description Prior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cenomanian
The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding age. Both age and stage bear the same name. As a unit of geologic time measure, the Cenomanian Age spans the time between 100.5 and 93.9 million years ago (Mya). In the geologic timescale, it is preceded by the Albian and is followed by the Turonian. The Upper Cenomanian starts around at 95 Mya. The Cenomanian is coeval with the Woodbinian of the regional timescale of the Gulf of Mexico and the early part of the Eaglefordian of the regional timescale of the East Coast of the United States. At the end of the Cenomanian, an anoxic event took place, called the Cenomanian-Turonian boundary event or the "Bonarelli event", that is associated with a minor extinction event for marine spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiger Shark
The tiger shark (''Galeocerdo cuvier'') is a species of requiem shark and the last extant member of the family Galeocerdonidae. It is a large macropredator, capable of attaining a length over . Populations are found in many tropical and temperate waters, especially around central Pacific islands. Its name derives from the dark stripes down its body, which resemble a tiger's pattern, but fade as the shark matures. The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, fish, seals, birds, squid, turtles, sea snakes, dolphins, and even other smaller sharks. It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Though apex predators, tiger sharks are sometimes taken as prey by groups of killer whales. It is considered a near threatened species because of finning and fishing by humans. The tiger s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronospecies
A chronospecies is a species derived from a anagenesis, sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is physically, Comparative anatomy, morphologically, and/or Genetics, genetically distinct from the original ancestors. Throughout the change, there is only one species in the lineage at any point in time, as opposed to cases where divergent evolution produces contemporary species with a common ancestor. The related term paleospecies (or palaeospecies) indicates an extinct species only identified with fossil material. That identification relies on distinct similarities between the earlier fossil specimens and some proposed descendant although the exact relationship to the later species is not always defined. In particular, the range of variation within all the early fossil specimens does not exceed the observed range that exists in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niche Differentiation
In ecology, niche differentiation (also known as niche segregation, niche separation and niche partitioning) refers to the process by which competing species use the environment differently in a way that helps them to coexist. The competitive exclusion principle states that if two species with identical niches (ecological roles) compete, then one will inevitably drive the other to extinction. This rule also states that two species cannot occupy the same exact niche in a habitat and coexist together, at least in a stable manner. When two species differentiate their niches, they tend to compete less strongly, and are thus more likely to coexist. Species can differentiate their niches in many ways, such as by consuming different foods, or using different areas of the environment. As an example of niche partitioning, several anole lizards in the Caribbean islands share common diets—mainly insects. They avoid competition by occupying different physical locations. Although these liz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapanorhynchus
''Scapanorhynchus'' (from el, σκάφιου , 'shovel' and el, ῥύγχος 'snout') is an extinct genus of shark that lived from the early Cretaceous until possibly the Miocene if ''S. subulatus'' is a mitsukurinid and not a sand shark.Capetta, H., Chondrichthyes II, Mesozoic and Cenozoic Elasmobranchii, vol. 3B of Handbook of Paleoichthyology, Stuttgart, New York: Gustav Fischer Verlag, 1987.Glickman, L. S., and A. O. Averianov. "Evolution of the Cretaceous Lamnoid sharks of the genus Eostriatolamia." PALEONTOLOGICAL JOURNAL C/C OF PALEONTOLOGICHESKII ZHURNAL 32 (1998): 376-384/ref> Their extreme similarities to the living goblin shark, ''Mitsukurina owstoni'', lead some experts to consider reclassifying it as ''Scapanorhynchus owstoni''. However, most shark specialists regard the goblin shark to be distinct enough from its prehistoric relatives to merit placement in its own genus. ''Scapanorhynchus'' had an elongated, albeit flattened snout and sharp awl-shaped teeth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretalamna
''Cretalamna'' is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to have ever lived, ''Otodus angustidens'', ''Otodus chubutensis'', and ''Otodus megalodon''. Taxonomy Research History ''Cretalamna'' was first described by Swiss naturalist Louis Agassiz using five teeth previously identified as the common smooth-hound and collected by English paleontologist Gideon Mantell from the Southerham Grey Pit near Lewes, East Sussex. In his 1835 publication ''Rapport sur les poissons fossiles découverts en Angleterre'', he reidentified them as a new species of porbeagle shark under the taxon ''Lamna appendiculata''. In 1843, Agassiz published ''Recherches sur les poissons fossiles'', which reexamined Mantell's five teeth. Using them, eight additional teeth collected by Mantell, and twenty more teeth collected by various paleontologists i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptychodus
''Ptychodus'' (from el, πτυχή 'fold' and el, ὀδούς 'tooth') is a genus of extinct durophagous (shell-crushing) sharks from the Late Cretaceous. Fossils of ''Ptychodus'' teeth are found in many Late Cretaceous marine sediments. Diet Diets of ''Ptychodus'', for example ''P. decurrens'' (found in southern India) were probably animals with hard shells. Bivalves and ammonites Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttl ... are example of shelled invertebrates that are probably main food source of ''Ptychodus''. '' Platyceramus'', genus that includes one of the largest bivalves at the time, is able to be a part of the diet of ''Ptychodus''. The ''Ptychodus'' diet in each species slightly differed based on the region they came from. The ''Paraptychodus washitaensis'' spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalicorax
''Squalicorax'', commonly known as the crow shark, is a genus of extinct lamniform shark known to have lived during the Cretaceous period. The genus had a global distribution in the Late Cretaceous epoch. Multiple species within this genus are considered to be wastebasket taxon due to morphological similarities in the teeth. Etymology The name ''Squalicorax'' is derived from the Latin ''squalus'' for shark and the Greek κόραξ, "''korax''" for raven. Description These sharks are of medium size, up to 5 m (usually around 2 m) in length. Their bodies were similar to the modern gray reef sharks, but the shape of the teeth is strikingly similar to that of a tiger shark. The teeth are numerous, relatively small, with a curved crown and serrated, up to 2.5 – 3 cm in height. Large numbers of fossil teeth have been found in Europe, North Africa, and North America. Squalicorax is one of three Cretaceous lamniformes to garner serrations along with '' Pseudocorax'' ... [...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] |
Sea Turtle
Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, Kemp's ridley, and olive ridley sea turtles. All six of the sea turtle species present in US waters (all of those listed above except the flatback) are listed as endangered and/or threatened under the Endangered Species Act. The seventh sea turtle species is the flatback, which exists in the waters of Australia, Papua New Guinea and Indonesia. Sea turtles can be separated into the categories of hard-shelled (cheloniid) and leathery-shelled ( dermochelyid).Wyneken, J. 2001. The Anatomy of Sea Turtles. U.S Department of Commerce NOAA Technical Memorandum NMFS-SEFSC-470, 1-172 pp. There is only one dermochelyid species which is the leatherback sea turtle. Description For each of the seven types of sea turtles, females and males are the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical region. Italy is also considered part of Western Europe, and shares land borders with France, Switzerland, Austria, Slovenia and the enclaved microstates of Vatican City and San Marino. It has a territorial exclave in Switzerland, Campione. Italy covers an area of , with a population of over 60 million. It is the third-most populous member state of the European Union, the sixth-most populous country in Europe, and the tenth-largest country in the continent by land area. Italy's capital and largest city is Rome. Italy was the native place of many civilizations such as the Italic peoples and the Etruscans, while due to its central geographic location in Southern Europe and the Mediterranean, the country has also historically been home ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kansas
Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named after the Kansas River, which in turn was named after the Kansa Native Americans who lived along its banks. The tribe's name (natively ') is often said to mean "people of the (south) wind" although this was probably not the term's original meaning. For thousands of years, what is now Kansas was home to numerous and diverse Native American tribes. Tribes in the eastern part of the state generally lived in villages along the river valleys. Tribes in the western part of the state were semi-nomadic and hunted large herds of bison. The first Euro-American settlement in Kansas occurred in 1827 at Fort Leavenworth. The pace of settlement accelerated in the 1850s, in the midst of political wars over the slavery debate. Wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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