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Gunakadeit
''Gunakadeit'' is an extinct genus of thalattosaur. It is known from a single species, ''Gunakadeit joseeae'', which is based on an articulated and mostly complete skeleton from the late Triassic (middle Norian) Hound Island Volcanics of Alaska. ''Gunakadeit'' possessed a variety of features from the two major suborders of thalattosaurs, Askeptosauroidea and Thalattosauroidea, and it is considered the most basal member of the latter group. Despite this, it is also the youngest known thalattosaur genus, with the group going extinct at the end of the Triassic. ''Gunakadeits basal position and relatively recent occurrence implies a 20-million-year ghost lineage connecting it to the rest of Thalattosauria. The skull ends in a sharply pointed and toothless tip like the askeptosauroid ''Endennasaurus'', but unlike ''Endennasaurus'', ''Gunakadeit'' had poorly developed joints and was likely exclusively aquatic in behavior. Discovery The holotype, UAMES 23258, was discovered by rar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gunakadeit Skull
''Gunakadeit'' is an extinct genus of thalattosaur. It is known from a single species, ''Gunakadeit joseeae'', which is based on an articulated and mostly complete skeleton from the late Triassic (middle Norian) Hound Island Volcanics of Alaska. ''Gunakadeit'' possessed a variety of features from the two major suborders of thalattosaurs, Askeptosauroidea and Thalattosauroidea, and it is considered the most basal member of the latter group. Despite this, it is also the youngest known thalattosaur genus, with the group going extinct at the end of the Triassic. ''Gunakadeits basal position and relatively recent occurrence implies a 20-million-year ghost lineage connecting it to the rest of Thalattosauria. The skull ends in a sharply pointed and toothless tip like the askeptosauroid ''Endennasaurus'', but unlike ''Endennasaurus'', ''Gunakadeit'' had poorly developed joints and was likely exclusively aquatic in behavior. Discovery The holotype, UAMES 23258, was discovered by rar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalattosaur
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] |
Thalattosauroidea
Thalattosauroidea is a superfamily of thalattosaurs, a Triassic group of marine reptiles. It was named in 1904 by paleontologist John Campbell Merriam to include the genus '' Thalattosaurus'' from California. Thalattosauroids are one of two groups of Thalattosauria, the other being Askeptosauroidea. Thalattosauroids make up the "traditional" thalattosaurs with large downturned snouts, short necks, and long, paddle-like tails. Classification Thalattosauria includes North American genera such as ''Thalattosaurus'' and ''Nectosaurus'' as well as recently described Chinese forms such as '' Xinpusaurus''. A 1999 study of thalattosaurs, which established much of the currently accepted phylogeny of the group, referred to Thalattosauroidea as Thalattosauria, while calling the larger group Thalattosauriformes. More recent phylogenetic studies have come upon the same conclusions, but refer to the group as Thalattosauroidea in order to contrast it with another superfamily of thalattosaurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic. The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of archo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Culture Of The Tlingit
The culture of the Tlingit people, Tlingit, an Indigenous peoples of the Pacific Northwest Coast, Indigenous people from Alaska, British Columbia, and the Yukon, is multifaceted, a characteristic of Northwest Coast peoples with access to easily exploited rich resources. In Tlingit culture a heavy emphasis is placed upon family and kinship, and on a rich tradition of oratory. Wealth and economic power are important indicators of status, but so is generosity and proper behavior, all signs of "good breeding" and ties to aristocracy. Art and spirituality are incorporated in nearly all areas of Tlingit culture, with even everyday objects such as spoons and storage boxes decorated and imbued with spiritual power and historical associations. Kinship The Tlingit kinship system, like most Northwest Coast societies, is based on a matrilineal structure, and describes a family roughly according to Morgan's Crow kinship, Crow system of kinship. The society is wholly divided into two distinct K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronoid Process Of The Mandible
In human anatomy, the mandible's coronoid process (from Greek ''korōnē'', denoting something hooked) is a thin, triangular eminence, which is flattened from side to side and varies in shape and size. Its anterior border is convex and is continuous below with the anterior border of the ramus. Its ''posterior border'' is concave and forms the anterior boundary of the mandibular notch. The ''lateral surface'' is smooth, and affords insertion to the temporalis and masseter muscles. Its ''medial surface'' gives insertion to the temporalis, and presents a ridge which begins near the apex of the process and runs downward and forward to the inner side of the last molar tooth. Between this ridge and the anterior border is a grooved triangular area, the upper part of which gives attachment to the temporalis, the lower part to some fibers of the buccinator. Clinical significance Fractures of the mandible are common. However, coronoid process fractures are very rare. Isolated fractures of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandibular Symphysis
In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral halves of the mandible typically fuse at an early period of life (1-2 years). It is not a true symphysis as there is no cartilage between the two sides of the mandible. This ridge divides below and encloses a triangular eminence, the mental protuberance, the base of which is depressed in the center but raised on either side to form the mental tubercle. The lowest (most inferior) end of the mandibular symphysis — the point of the chin — is called the "menton". It serves as the origin for the geniohyoid and the genioglossus muscles. Other animals Solitary mammalian carnivores that rely on a powerful canine bite to subdue their prey have a strong mandibular symphysis, while pack hunters delivering shallow bites have a weaker one. When filter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supratemporal Bone
The supratemporal bone is a paired cranial bone present in many tetrapods and tetrapodomorph fish. It is part of the temporal region (the portion of the skull roof behind the eyes), usually lying medial (inwards) relative to the squamosal and lateral (outwards) relative to the parietal and/or postparietal. It may also contact the postorbital or intertemporal (which lie forwards), or tabular (which lies backwards), when those bones are present. The supratemporal is a common component of the skull in many extinct amphibians, though it is apparently absent in the lightweight skulls of living lissamphibians (frogs and salamanders). Embryological studies of salamanders suggests that the supratemporal fuses with the squamosal in early development. A separate supratemporal was retained by early synapsids and reptiles, but was strongly reduced in many groups. Squamates (lizards and snakes) still possess a small supratemporal, though archosaurs (crocodilians and birds) and mammals lack i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parietal Bone
The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin ''paries'' (''-ietis''), wall. Surfaces External The external surface [Fig. 1] is convex, smooth, and marked near the center by an eminence, the parietal eminence (''tuber parietale''), which indicates the point where ossification commenced. Crossing the middle of the bone in an arched direction are two curved lines, the superior and inferior temporal lines; the former gives attachment to the temporal fascia, and the latter indicates the upper limit of the muscular origin of the temporal muscle. Above these lines the bone is covered by a tough layer of fibrous tissue – the epicranial aponeurosis; below them it forms part of the temporal fossa, and affords attachment to the temporal muscle. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supratemporal Fenestra
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, these two parts are the neurocranium and the viscerocranium (facial skeleton) that includes the mandible as its largest bone. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth. In humans these sensory structures are part of the facial skeleton. Functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to enable sound localisation of the direction and distance of sounds. In some animals, such as horned ungulates (mammals with hooves), the skull also has a defensive function by providing the mount (on the frontal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugal Bone
The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy The jugal bone is located on either side of the skull in the circumorbital region. It is the origin of several masticatory muscles in the skull. The jugal and lacrimal bones are the only two remaining from the ancestral circumorbital series: the prefrontal, postfrontal, postorbital, jugal, and lacrimal bones. During development, the jugal bone originates from dermal bone. In dinosaurs This bone is considered key in the determination of general traits in cases in which the entire skull has not been found intact (for instance, as with dinosaurs in paleontology). In some dinosaur genera the jugal also forms part of the lower margin of either the antorbital fenestra or the infratemporal fenestra, or both. Most commonly, this bone articu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is , of which the eye occupies . The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves. Structure The orbits are conical or four-sided pyramidal cavities, which open into the midline of the face and point back into the head. Each consists of a base, an apex and four walls."eye, human."Encyclopædia Britannica from Encyclopædia Britannica 2006 Ultimate Reference Suite DVD 2009 Openings There are two important foramina, or windows, two important fissu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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