|
Demopolis Chalk
The Demopolis Chalk is a geological Formation (geology), formation in North America, within the United States, U.S. states of Alabama, Mississippi, and Tennessee. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment during the middle Campanian age (geology), age of the Late Cretaceous. It is a unit of the Selma Group and consists of the upper Bluffport Marl Member and a lower unnamed member. Dinosaur and mosasaur remains are among the fossils that have been recovered from the Demopolis Chalk.Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 574-588. . Vertebrate paleofauna Fish Cartilaginous fish Bony fish Reptiles Dinosaurs Indeterminate hadrosaurid remains have been found in Tennessee. Possible indeterminate tyrannosaurid remains have been fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Age (geology)
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardised international units of geological time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapanorhynchus
''Scapanorhynchus'' (from , 'shovel' and 'snout') is an extinct genus of shark belonging to the family Mitsukurinidae, that lived during the Cretaceous period, from the Aptian to the end of the Maastrichtian. It is a close relative of the living goblin shark (''Mitsukurina owston''i), the only living member of the family. Later claimed record of ''Scapanorhynchus'', such as those from the Miocene assigned to the species ''S. subulatus'', are highly dubious and may be misidentified sand sharks.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> It was the first mitsukurinid to be described, with the type species (''S. lewisii'') being described nearly 10 years before the living g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischyrhiza
''Ischyrhiza'' is an extinct genus of sclerorhynchoid ray from the Late Cretaceous (Cenomanian-Maastrichtian). It had a large, toothed rostrum closely resembling that of a modern-day sawfish. Despite formerly being classified within a family of extinct sawfish-like rays known as Sclerorhynchidae, phylogenetic analyses indicate that ''Ischyrhiza, Schizorhiza'', and ''Onchopristis'' form a distinct clade that groups closer with the extant family Rajidae, which contains the true skates, possibly rendering the suborder Sclerorhynchoidei paraphyletic. Fossils of the genus have been found in Canada, the United States, the Aguja Formation of Mexico, the Bissekty Formation of Uzbekistan, the Tamayama Formation of Japan, the Dukamaje Formation The Dukamaje Formation is a geological formation in Niger and Nigeria whose strata date back to the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otodontidae
Otodontidae is an extinct family of sharks belonging to the order Lamniformes. Its members have been described as megatoothed sharks. They lived from the Early Cretaceous to the Pliocene, and included genera such as '' Otodus,'' including the giant megalodon ''Otodus megalodon'' ( ; meaning "big tooth"), Common name, commonly known as megalodon, is an extinction, extinct species of giant mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Earl .... Recent studies of the newly described genus '' Megalolamna'' indicate that the members of the genus ''Carcharocles'' should be reclassified as members of the genus ''Otodus''. The genus '' Cretalamna'' which lived from the mid-Cretaceous-Paleogene is believed to be directly ancestral to ''Otodus,'' and thus to megalodon. There are certain dubious species of ''Otodontidae'' included species where teeth are not properly described, such as '' Otodus debrayi'', '' Otodus stromeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretolamna
''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, such as '' 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 paleo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalicorax2DB
''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 ''Squalicorax'' was a medium-sized shark, typically measuring about long. The largest specimen of ''S. pristodontus'', SDSM 47683, was significantly larger, measuring up to long. 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. Squa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischyrhiza Mira
''Ischyrhiza'' is an extinct genus of sclerorhynchoid ray from the Late Cretaceous (Cenomanian-Maastrichtian). It had a large, toothed rostrum closely resembling that of a modern-day sawfish. Despite formerly being classified within a family of extinct sawfish-like rays known as Sclerorhynchidae, phylogenetic analyses indicate that ''Ischyrhiza, Schizorhiza'', and ''Onchopristis'' form a distinct clade that groups closer with the extant family Rajidae, which contains the true skates, possibly rendering the suborder Sclerorhynchoidei paraphyletic. Fossils of the genus have been found in Canada, the United States, the Aguja Formation of Mexico, the Bissekty Formation of Uzbekistan, the Tamayama Formation of Japan, the Dukamaje Formation The Dukamaje Formation is a geological formation in Niger and Nigeria whose strata date back to the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cartilaginous Fish
Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Extant chondrichthyans range in size from the finless sleeper ray to the over whale shark. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
