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Agkistrognathus
''Agkistrognathus'' is an extinct genus of thalattosaurian which lived in the early to middle Triassic of British Columbia, Canada. There is only one species known in this genus, ''Agkistrognathus campbelli''. The genus name translates to "hook jaw" while the species name refers to Bob Campbell, who discovered the only known specimen. Description ''Agkistrognathus'' is a thalattosaurian, a group of marine reptiles with long, paddle-like tails and independently movable digits. ''Agkistrognathus'' can be distinguished from other thalattosaurians due to having conical, closely spaced teeth which are smallest in the middle of the jaw and deep dentaries with hooked front ends. These features may have given it a powerful bite . The dentaries are also bifurcated at their posterior ends, with both forks being the same length but the dorsal one being much deeper. This combination is unique to ''Agkistrognathus''. ''Agkistrognathus'' is probably closely related to ''Thalattosaurus'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalattosaur
Thalattosauria (Attic Greek, Greek for "sea lizards") is an extinct Order (biology), order of prehistoric marine reptiles that lived in the middle to late Triassic period. Thalattosaurs were diverse in size and shape, and are divided into two superfamilies: Askeptosauroidea and Thalattosauroidea. Askeptosauroids were endemic to the Tethys Ocean, their fossils have been found in Europe and China, and they were likely semiaquatic fish eaters with straight snouts and decent terrestrial abilities. Thalattosauroids were more specialized for aquatic life and most had unusual downturned snouts and crushing dentition. Thalattosauroids lived along the coasts of both Panthalassa and the Tethys Ocean, and were most diverse in China and western North America. The largest species of thalattosaurs grew to over 4 meters (13 feet) in length, including a long, flattened tail utilized in underwater propulsion. Although thalattosaurs bore a superficial resemblance to lizards, their exact relation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalattosaurs
Thalattosauria (Greek for "sea lizards") is an extinct order of prehistoric marine reptiles that lived in the middle to late Triassic period. Thalattosaurs were diverse in size and shape, and are divided into two superfamilies: Askeptosauroidea and Thalattosauroidea. Askeptosauroids were endemic to the Tethys Ocean, their fossils have been found in Europe and China, and they were likely semiaquatic fish eaters with straight snouts and decent terrestrial abilities. Thalattosauroids were more specialized for aquatic life and most had unusual downturned snouts and crushing dentition. Thalattosauroids lived along the coasts of both Panthalassa and the Tethys Ocean, and were most diverse in China and western North America. The largest species of thalattosaurs grew to over 4 meters (13 feet) in length, including a long, flattened tail utilized in underwater propulsion. Although thalattosaurs bore a superficial resemblance to lizards, their exact relationships are unresolved. They ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Mountain Formation
The Sulphur Mountain Formation is a geologic formation of Early to Middle Triassic age. It is present on the western edge of the Western Canada Sedimentary Basin in the foothills and Rocky Mountains of western Alberta and northeastern British Columbia. It includes marine fossils from the time shortly after the Permian-Triassic extinction event.Noad, Jon, 2017. Field trip to examine Montney Formation analogs: Exposures of the Sulphur Mountain Formation around Canmore and Kananaskis, western Alberta, Canada. In: J.C.C. Hseih, ed., Geologic field trips of the Canadian Rockies: 2017 meeting of the GSA Rocky Mountain Section, Geological Society of America, Field Guide 48, p. 137-152; doi: 10.1130/2017.0048(05). The Sulphur Mountain Formation was first described as a member of the Spray River Formation by P.S. Warren in 1945, who named it for Sulphur Mountain in Banff National Park. It was later raised to formation status. Its type section is located in the Spray River gorge at the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and Ma (million years ago). It is preceded by the Early Triassic Epoch and followed by the Late Triassic Epoch. The Middle Triassic is divided into the Anisian and Ladinian ages or stages. Formerly the middle series in the Triassic was also known as Muschelkalk. This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe. Middle Triassic fauna Following the Permian–Triassic extinction event, the most devastating of all mass-extinctions, life recovered slowly. In the Middle Triassic, many groups of organisms reached higher diversity again, such as the marine reptiles (e.g. ichthyosaurs, sauropterygians, thallatosaurs), ray-finned fish and many invertebrate g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ladinian
The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic). The Ladinian is coeval with the Falangian regional stage used in China. Stratigraphic definitions The Ladinian was established by Austrian geologist Alexander Bittner in 1892. Its name comes from the Ladin people that live in the Italian Alps (in the Dolomites, then part of Austria-Hungary). The base of the Ladinian Stage is defined as the place in the stratigraphic record where the ammonite species '' Eoprotrachyceras curionii'' first appears or the first appearance of the conodont '' Budurovignathus praehungaricus''. The global reference profile for the base (the GSSP) is at an outcrop in the river bed of the Caffaro river at Bagolino, in the province of Brescia, northern Italy.The GSSP was established by Brack ''et al.'' (200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Splenial
The splenial is a small bone in the lower jaw of reptiles, amphibians and birds, usually located on the lingual side (closest to the tongue) between the angular and surangular The suprangular or surangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular, splenial and articular The articular bone ....Watson, D. M. S. (1912). LXVII.—On some reptilian lower jaws. Journal of Natural History, 10(60), 573-587. References Vertebrate anatomy {{Vertebrate anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Bone
The angular is a large bone in the lower jaw (mandible) of amphibians and reptiles (birds included), which is connected to all other lower jaw bones: the dentary (which is the entire lower jaw in mammals), the splenial, the suprangular, and the articular. It is homologous to the tympanic bone in mammals, due to the incorporation of several jaw bones into the mammalian middle ear early in mammal evolution. In therapsids (mammal ancestors and their kin), the lower jaw is made up of the dentary (the mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ... in mammals) and a group of smaller "postdentary" bones near the jaw joint. As the dentary increased in size over million of years, two of these postdentary bones, the articular and angular, became increasingly reduced and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vomer
The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms the inferior part of the nasal septum in humans, with the superior part formed by the perpendicular plate of the ethmoid bone. The name is derived from the Latin word for a ploughshare and the shape of the bone. In humans The vomer is situated in the median plane, but its anterior portion is frequently bent to one side. It is thin, somewhat quadrilateral in shape, and forms the hinder and lower part of the nasal septum; it has two surfaces and four borders. The surfaces are marked by small furrows for blood vessels, and on each is the nasopalatine groove, which runs obliquely downward and forward, and lodges the nasopalatine nerve and vessels. Borders The ''superior border'', the thickest, presents a d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has been usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or ''os premaxillare'', intermaxillary bone or ''os intermaxillare'', and Goethe's bone. Human anatomy In human anatomy, the premaxilla is referred to as the incisive bone (') and is the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region. In the nasal cavity, the premaxillary element projects higher than the maxillary element behind. The palatal portion of the premaxilla is a bony plate with a generally transverse orientation. The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla. It is formed from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxillary bones are fused at the intermaxillary suture, forming the anterior nasal spine. This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis. The mandible is the movable part of the jaw. Structure In humans, the maxilla consists of: * The body of the maxilla * Four processes ** the zygomatic process ** the frontal process of maxilla ** the alveolar process ** the palatine process * three surfaces – anterior, posterior, medial * the Infraorbital foramen * the maxillary sinus * the incisive foramen Articulations Each maxilla articulates with nine bones: * two of the cranium: the frontal and ethmoid * seven of the face: the nasal, zygomatic, lacrimal, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly '' Plebejus idas longinus'' is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University. In botany, an isotype is a duplicate of the holotype, where holotype and isotypes are often pieces from the same individual plant or samples from the same gathering. A holotype is not necessaril ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conodont
Conodonts ( Greek ''kōnos'', " cone", + ''odont'', " tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which are usually found in isolation and are now called conodont elements. Knowledge about soft tissues remains limited. They existed in the world's oceans for over 300 million years, from the Cambrian to the beginning of the Jurassic. Conodont elements are widely used as index fossils, fossils used to define and identify geological periods. The animals are also called Conodontophora (conodont bearers) to avoid ambiguity. Discovery and understanding of conodonts The teeth-like fossils of the conodont were first discovered by Heinz Christian Pander and the results published in Saint Petersburg, Russia, in 1856. The name ''pander'' is commonly used in scientific names of conodonts. It was only in the early 1980s that the first fossil evi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
