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Severn Formation
The Severn Formation is a Mesozoic geologic formation in Maryland. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. Paleofauna Dinosaurs * '' "Coelosaurus" antiquus'' * Ornithomimidae indet. *Hadrosauridae indet. Plesiosaurs * '' Cimoliasaurus magnus'' Mosasaurs * '' Halisaurus platyspondylus'' * ''Prognathodon rapax'' * ''Mosasaurus hoffmanni'' * ''Mosasaurus sp''. * cf. ''Mosasaurus conodon'' * Mosasauridae indet. Crocodylomorphs * ''Deinosuchus rugosus'' * ''Thoracosaurus neocesariensis'' * Alligatorinae indet. Turtles * ''Peritresius ornatus'' * '' Osteopygis emarginatus'' * '' Trionyx priscus'' * Toxochelyidae indet. Chondrichthyans * '' Carcharias holmdelensis'' * ''Carcharias samhammeri'' * '' Chiloscyllium greeni'' * '' Cretalamana appendiculata'' * ''Dasyatis sp.'' * '' Tomewingia problematica'' * '' Galeorhinus garadoti'' ... [...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] |
Mosasaurus Conodon
''Mosasaurus'' (; "lizard of the Meuse River") is the type genus (defining example) of the mosasaurs, an extinct group of aquatic squamate reptiles. It lived from about 82 to 66 million years ago during the Campanian and Maastrichtian stages of the Late Cretaceous. The earliest fossils of ''Mosasaurus'' known to science were found as skulls in a chalk quarry near the Dutch city of Maastricht in the late 18th century, which were initially thought to have been the bones of crocodiles or whales. One skull discovered around 1780, and which was seized by France during the French Revolutionary Wars for its scientific value, was famously nicknamed the "great animal of Maastricht". In 1808, naturalist Georges Cuvier concluded that it belonged to a giant marine lizard with similarities to monitor lizards but otherwise unlike any known living animal. This concept was revolutionary at the time and helped support the then-developing ideas of extinction. Cuvier did not designate a scientif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiloscyllium
''Chiloscyllium'' is a genus of sharks in the family Hemiscylliidae. This genus is distinguished by a relatively long snout with subterminal nostrils. The eyes and supraorbital ridges are hardly elevated. The mouth is closer to the eyes than to the tip of the snout, with lower labial folds usually connected across the chin by a flap of skin. The pectoral and pelvic fins are thin and not very muscular. No black hood on the head or large black spot on the side is present (though juveniles often are strongly marked with dark spots/bars). * ''Chiloscyllium arabicum'' Gubanov, 1980 (Arabian carpetshark) * ''Chiloscyllium burmensis'' Dingerkus & DeFino, 1983 (Burmese bamboo shark) * ''Chiloscyllium griseum'' J. P. Müller & Henle, 1838 (grey bamboo shark) * ''Chiloscyllium hasselti'' Bleeker, 1852 (Hasselt's bamboo shark) * ''Chiloscyllium indicum'' ( J. F. Gmelin, 1789) (slender bamboo shark) * ''Chiloscyllium plagiosum The whitespotted bamboo shark (''Chiloscyllium plagio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcharias
''Carcharias'' is a genus of sand tiger sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark. Description ''Carcharias'' are 2.5 m long on average. The maximum weight of the shark is 158.8 kg. Differentiating species of sharks is usually done by locating and measuring their fins. The second dorsal fin and the anal fin of ''Carcharias'' are very large. In fact, they are about equal in size. The pectoral fins are triangular and only slightly larger than the dorsal fins. The teeth are very long and narrow with sharp points. The teeth are smooth with no ridges. The tail is one third of the entire body size. Diet ''Carcharias'' species hunt bony fish, small sharks, rays, squids, crabs, and lobsters. Habitat Sand tiger sharks live in water depths ranging from 0 to 190 meters. They are found in the Pacific, Atlantic, and Indian oceans. They are commonl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyes
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. Chondrichthyes are jawed vertebrates with paired fins, paired nares, scales, and a heart with its chambers in series. Extant chondrichthyes range in size from the 10 cm (3.9 in) finless sleeper ray to the 10 m (32 ft) whale shark. 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). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxochelyidae
''Toxochelys'' () is an extinct genus of marine turtle from the Late Cretaceous period. It is the most commonly found fossilized turtle species in the Smoky Hill Chalk, in western Kansas. Description ''Toxochelys'' was about 2 m (6 ft) in length. Two species in the genus are recognized, ''Toxochelys latiremis'' and ''Toxochelys moorevillensis''. Phylogenetic analysis shows that ''Toxochelys'' belong to an extinct lineage of turtles transitional between modern sea turtles 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, ... and other turtles. ''Toxochelys bauri'' Williston, 1905, based on the skeleton YPM 1786, is a synonym of '' Ctenochelys stenoporus''.R. Zangerl. 1953. The vertebrate fauna of the Selma Formation of Alabama. Part IV. The turtles of the family Toxochelyid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trionyx
''Trionyx'' is a genus of softshell turtles belonging to the family Trionychidae. In the past many species in the family were classified in this genus, but today '' T. triunguis'', the African or Nile softshell turtle, is the only extant softshell still classified as ''Trionyx''. The other species still assigned to this genus are only known from fossils. ''T. triunguis'' is a relatively large, aquatic piscivore. Species The list of species follows a 2017 review of the Trionychidae by Georgios L. Georgalis and Walter G. Joyce. * '' Trionyx triunguis'' ( Forsskål, 1775) – African or Nile softshell turtle * † '' Trionyx pliocenicus'' Fucini, 1912 – Pliocene of Tuscany (Italy) * † '' Trionyx vindobonensis'' (Peters, 1855) – Miocene of Vienna (Austria) The following species are considered valid trionychid taxa, but with uncertain phylogenetic relationships. They are only referred to ''Trionyx'' provisionally due to its historic status as a wastebasket taxon Wasteb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteopygis
''Osteopygis'' is a genus of extinct turtle. ''Osteopygis'', as traditionally seen, is a chimera: the postcrania (including the holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...) belong to a non-marine stem-cryptodire, whilst the crania belong to sea turtles. In 2005 the referred material was split between two taxa: the postcrania remained in ''Osteopygis'', while the crania were reassigned to '' Euclastes wielandi''. References Macrobaenidae Nomina dubia Fossil taxa described in 1868 Taxa named by Edward Drinker Cope Extinct turtles {{turtle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peritresius
''Peritresius'' is an extinct genus of 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, loggerhe ... from the Late Cretaceous deposits in the US Eastern Seaboard. Taxonomy Two species are known, ''Peritresius ornatus'' Leidy, 1856 and ''P. martini'' Gentry, Parham, Ehret, and Ebersole, 2018, both from Campanian-Maastrichtian age deposits in New Jersey, Alabama, and Mississippi.Gentry AD, Parham JF, Ehret DJ, Ebersole JA (2018) A new species of Peritresius Leidy, 1856 (Testudines: Pan-Cheloniidae) from the Late Cretaceous (Campanian) of Alabama, USA, and the occurrence of the genus within the Mississippi Embayment of North America. PLoS ONE 13(4): e0195651. https://doi.org/10.1371/journal.pone.0195651 References Cheloniidae Cretaceous turtles Extinct animals of the United S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turtle
Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked turtles), which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins. They are found on most continents, some islands and, in the case of sea turtles, much of the ocean. Like other amniotes (reptiles, birds, and mammals) they breathe air and do not lay eggs underwater, although many species live in or around water. Turtle shells are made mostly of bone; the upper part is the domed carapace, while the underside is the flatter plastron or belly-plate. Its outer surface is covered in scales made of keratin, the material of hair, horns, and claws. The carapace bones develop from ribs that grow sideways and develop into broad flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alligatorinae
Alligatorinae is a subfamily within the family Alligatoridae that contains the alligators and their closest extinct relatives, and is the sister taxon to Caimaninae (the caimans). Many genera in Alligatorinae are described, but only the genus ''Alligator'' is still living, with the remaining genera extinct. Evolution Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million to about 65 million years ago). The Chinese alligator split from the American alligator about 33 million years ago and likely descended from a lineage that crossed the Bering land bridge during the Neogene. The modern American alligator is well represented in the fossil record of the Pleistocene. The alligator's full mitochondrial genome was sequenced in the 1990s. The full genome, published in 2014, suggests that the alligator evolved much more slowly than mammals and birds. Phylogeny Alligatorinae is cladistically defined as ''Alligator mississippiensis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thoracosaurus
''Thoracosaurus'' is an extinct genus of eusuchian crocodylomorph which existed during the Late Cretaceous and Early Paleocene in North America and Europe. The taxon had traditionally been thought to be related to the modern false gharial, largely because the nasal bones contact the premaxillae. Phylogenetic work starting in the 1990s instead supported affinities within Gavialoidea exclusive of such forms, although a 2018 tip dating study simultaneously using morphological, molecular ( DNA sequencing), and stratigraphic (fossil age) data suggests that it might have been a non-crocodylian eusuchian. The genus contains the type species ''Thoracosaurus neocesariensis'' in North America, and what is either ''Thoracosaurus isorhynchus'' or ''Thoracosaurus macrorhynchus'' from Europe; a recent review argues that ''T. macrorhynchus'' is a junior synonym of ''T. isorhynchus,'' but it is unclear whether the type of ''T. isorhynchus'' allows differentiation of European and North American ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
