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Ojo Alamo Formation
The Ojo Alamo Formation is a geologic Formation (geology), formation in New Mexico spanning the Mesozoic/Cenozoic boundary. Non-avian dinosaur fossils have controversially been identified in beds of this formation dating from after the Cretaceous–Paleogene extinction event, but these have been explained as either misidentification of the beds in question or as reworked fossils, fossils eroded from older beds and redeposited in the younger beds. Description The Ojo Alamo Formation is divided into two subunits separated by a large unconformity—a gap in the geologic record. The lower Naashoibito member (sometimes considered part of the Kirtland Formation) was deposited during the Maastrichtian age of the Cretaceous period, specifically between about 69-68 million years ago. It overlies the De-na-zin member of the Kirtland formation, though the two are separated by another large unconformity that spans a period of geologic time equivalent to 73-69 million years ago.Sullivan, R.M., ... [...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] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ninth and longest geological period of the entire Phanerozoic. The name is derived from the Latin , 'chalk', which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation . The Cretaceous was a period with a relatively warm climate, resulting in high Sea level#Local and eustatic, eustatic sea levels that created numerous shallow Inland sea (geology), 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 largely ice-free, although there is some evidence of brief periods of glaciation during the cooler first half, and forests extended to the poles. Many of the dominant taxonomic gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compsemys
''Compsemys '' is an extinct genus of prehistoric turtles from the Late Cretaceous and Paleocene of North America and possibly Europe. The type species ''C. victa'', first described by Joseph Leidy from the Hell Creek Formation in Montana in 1856, and another probable species ''C. russelli'' (originally placed in the separate genus '' Berruchelus''), described in 2012, from Paleocene deposits in France''.'' Its affinites have long been uncertain, but it has recently been considered to be the most basal member of Paracryptodira, despite the clade first appearing in the Late Jurassic, and is sometimes included in its own family, Compsemydidae. A revision in 2020 found Compsemydidae to be more expansive, also containing ''Riodevemys'' and ''Selenemys'' from the Late Jurassic of Europe, and '' Peltochelys'' from the Early Cretaceous of Europe. ''Compsemys'' was a moderately sized turtle, up to long, with a carapace covered with raised, flattened tubercles, which are not seen in any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opisthotriton
''Opisthotriton'' is an extinct genus of prehistoric salamanders that lived in North America between at least the Upper Cretaceous and the Paleocene. See also * List of prehistoric amphibians This list of prehistoric amphibians is an attempt to create a comprehensive listing of all genera from the fossil record that have ever been considered to be amphibians, excluding purely vernacular terms. The list includes all commonly accepted gen ... References Prehistoric amphibian genera Cenozoic salamanders Late Cretaceous amphibians Cretaceous amphibians of North America Cretaceous United States Hell Creek fauna Laramie Formation Cretaceous–Paleogene boundary Fossils of Canada Paleontology in Alberta Paleontology in Saskatchewan Fossil taxa described in 1961 {{paleo-salamander-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batrachosauroididae
Batrachosauroididae is an extinct family of prehistoric salamanders with holarctic distribution. They were paedomorphic and presumably aquatic. They are possibly the sister taxon of Proteidae, an extant family of aquatic salamanders. They are definitively known from the Late Cretaceous to Miocene of North America and Europe. Remains from the earliest Cretaceous (Berriasian) Lulworth Formation of England have tenatively been attributed to this family. The following genera are included: *'' Batrachosauroides'' United States, Eocene–Miocene *'' Opisthotriton'' North America, Late Cretaceous–Paleocene *'' Palaeoproteus'' Europe, Paleocene–Miocene *''Parrisia'' United States, Late Cretaceous *'' Peratosauroides'' United States, Miocene *'' Prodesmodon'' North America, Late Cretaceous–Paleocene See also * Prehistoric amphibian * List of prehistoric amphibians This list of prehistoric amphibians is an attempt to create a comprehensive listing of all genera from the fossil reco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lepisosteidae
Gars are an ancient group of ray-finned fish in the Family (biology), family Lepisosteidae. They comprise seven living species of fish in two genera that inhabit Fresh water, fresh, Brackish water, brackish, and occasionally marine waters of eastern North America, Central America and Cuba in the Caribbean, though extinct members of the family were more widespread. They are the only surviving members of the Ginglymodi, a clade of fish which first appeared during the Triassic period, over 240 million years ago, and are one of only two surviving groups of holosteian fish, alongside the bowfins, which have a similar distribution. Gars have elongated bodies that are heavily armored with ganoid scales, and fronted by similarly elongated jaws filled with long, sharp teeth. Gars are sometimes referred to as "garpike", but are not closely related to pike (fish), pike, which are in the fish family Esocidae. All of the gars are relatively large fish, but the alligator gar (''Atractost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wobbegong
Wobbegong is the common name given to the 12 species of carpet sharks in the family Orectolobidae. They are found in shallow temperate and tropical waters of the western Pacific Ocean and eastern Indian Ocean, chiefly around Australia and Indonesia, although one species (the Japanese wobbegong, ''Orectolobus japonicus'') occurs as far north as Japan. The word ''wobbegong'' is believed to come from an Australian Aboriginal language, meaning "shaggy beard", referring to the growths around the mouth of the shark of the western Pacific. Description Wobbegongs are bottom-dwelling sharks, spending much of their time resting on the sea floor. Most species have a maximum length of , but the largest, the spotted wobbegong, ''Orectolobus maculatus'', and banded wobbegong, ''O. halei'', reach about in length. Wobbegongs are well camouflaged with a symmetrical pattern of bold markings which resembles a carpet. Because of this striking pattern, wobbegongs and their close relatives are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squatirhina
''Squatirhina'' is a genus of Late Cretaceous cartilaginous fish whose fossils have been found in the Aguja and Pen Formations of Big Bend National Park, Texas, USA. See also * List of prehistoric cartilaginous fish This list of prehistoric cartilaginous fish genera is an attempt to create a comprehensive listing of all Genus, genera that have ever been included in the class chondrichthyes ''and'' are known from the fossil record. This list excludes purely v ... Footnotes References * Hunt, ReBecca K., Vincent L. Santucci and Jason Kenworthy. 2006. "A preliminary inventory of fossil fish from National Park Service units." in S.G. Lucas, J.A. Spielmann, P.M. Hester, J.P. Kenworthy, and V.L. Santucci (ed.s), Fossils from Federal Lands. New Mexico Museum of Natural History and Science Bulletin 34, pp. 63–69. Prehistoric cartilaginous fish genera Cretaceous cartilaginous fish Late Cretaceous fish of North America Laramie Formation Ojo Alamo Formation {{B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmobranchii
Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks ( division Selachii), and batomorphs (division Batomorphi, including rays, skates, and sawfish). Members of this subclass are characterised by having five to seven pairs of gill slits opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil. The definition of the clade is unclear with respect to fossil chondrichthyans. Some authors consider it as equivalent to Neoselachii (the crown group clade including modern sharks, rays, and all o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anacoracidae
Anacoracidae is a family of extinct mackerel sharks that lived during the Cretaceous. It includes four valid genera: '' Nanocorax'', ''Ptychocorax'', '' Scindocorax'', and ''Squalicorax''. Two previously-included genera, ''Galeocorax'' and ''Pseudocorax ''Pseudocorax'' is an extinct genus of mackerel sharks that lived during the Late Cretaceous. It contains six valid species that have been found in Europe, the Middle East, North Africa, and North America. It was formerly assigned to the family ...'', were reassigned to the family Pseudocoracidae. References Shark families Prehistoric cartilaginous fish families Taxa named by Henri Cappetta Cretaceous first appearances Cretaceous extinctions {{paleo-shark-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myledaphus
''Myledaphus'' is an extinct genus of guitarfish. It currently contains four valid species found in North America (''M. bipartitus'', ''M. pustulosus''), South America (''M. araucanus''), and Central Asia (''M. tritus''). It is confirmed to have lived during the Late Cretaceous, with possible occurrences in the Paleocene and early Eocene. While the genus is mostly known from teeth, two partial skeletons of ''M. bipartitus'' have been found in the Dinosaur Park Formation of Alberta. Biology ''Myledaphus'' remains have been found both in marine and fluvial (freshwater) deposits, suggesting it could tolerate a range of salinity.Hoffman, Brian L. et al. “Dental Structure of the Late Cretaceous (Maastrichtian) Guitarfish (Neoselachii: Batoidea) Myledaphus pustulosus from the Hell Creek Formation of Garfield County, Montana.” ''Transactions of the Kansas Academy of Science'' 121 (2018): 279 - 296. This genus was able to move into the North American continent due to an interconti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutionary history, evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, Evolution of birds, having evolved from earlier Theropoda, theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomy (biology), taxonomic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
