|
Entelodonts
Entelodontidae, the entelodonts, are an extinct family of pig-like artiodactyls (even-toed ungulates) which inhabited the Northern Hemisphere (Asia, Europe, and North America) from the late Eocene to the Middle Miocene epochs, about 38-19 million years ago. Their large heads, low snouts, narrow gait, and proposed omnivorous diet inspires comparisons to suids (true pigs) and tayassuids (peccaries), and historically they have been considered closely related to these families purely on a morphological basis. However, studies which combine morphological and molecular (genetic) data on artiodactyls instead suggest that entelodonts are cetancodontamorphs, more closely related to hippos and cetaceans than to pigs or other ungulates. Description Entelodonts could get quite large, and in many cases are the largest mammals in their respective ecosystems. The largest entelodont known from a complete skeleton was ''Daeodon'', a North American entelodont which could reach an estimated weig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeotherium Mortoni 01
''Archaeotherium'' ( grc, αρχαιοθήριον, meaning "ancient beast") is an extinct genus of entelodont artiodactyl endemic to North America during the Eocene and Oligocene epochs (35—28 mya), existing for approximately . ''Archaeotherium'' fossils are most common in the White River Formation of the Great Plains, but it has also been found in the John Day Basin of Oregon and the Trans-Pecos area of Texas. Taxonomy ''Archaeotherium'' was named by Joseph Leidy (1850Its type is ''Archaeotherium mortoni''. It was synonymized subjectively with ''Entelodon'' by Leidy (1853) and synonymized subjectively with ''Elotherium'' by Leidy (1857). It was assigned to Entelodontidae by Leidy (1850), Peterson (1909), Scott (1940), Galbreath (1953), Russell (1980), Carroll (1988) and Effinger (1998). ''Archaeotherium'', along with all other Entelodontidae, is an artiodactyl whose exact taxonomic position has been disputed, but taxonomists agree the group lies between the Suina (pi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daeodon
''Daeodon'' is an extinct genus of entelodont even-toed ungulates that inhabited North America about 23 to 20 million years ago during the latest Oligocene and earliest Miocene. The type species is ''Daeodon shoshonensis'', described by a very questionable holotype by Cope. Some authors synonimize it with ''Dinohyus hollandi'' and several other species (see below), but due to the lack of diagnostic material, this is questionable at best. Another large member of this family, similar in size to ''Daeodon'', is the Asian ''Paraentelodon,'' but it is known by very incomplete material. Taxonomy The genus ''Daeodon'' was erected by the American anatomist and paleontologist Edward Drinker Cope in 1878. He classified it as a perissodactyl and thought that it was closely related to '' Menodus''. This classification persisted until the description of ''"Elotherium" calkinsi'' in 1905, a very similar and much more complete animal from the same rocks, which was promptly assigned as a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraentelodon
''Paraentelodon'' is an extinct entelodont from the Late Oligocene and Oligocene-Miocene boundary of Asia. The fossils of the type species ''P. intermedium'' were found in Georgia, Kazakhstan and China. An indeterminate species represents in Bugti Hills which is the late Oligocene of Pakistan.G. Métais, P.-O. Antoine, L. Marivaux, J.-L. Welcomme, and S. Ducrocq. 2003New artiodactyl ruminant mammal from the late Oligocene of Pakistan Acta Palaeontologica Polonica 48(3):375-382 Discovery and naming ''Paraentelodon'' was named by L. K. Gabunia in 1964 basing on molars and canine teeth that were found in Oligocene sites of Benara, Georgia (Georgian SSR at the time of discovery). It was assigned to Entelodontidae by Carroll (1988). In 1996 Lucas and Emry found ''Neoentelodon'' to be synonymous with ''Paraentelodon''. Although Gabunia did not explain the etymology, the name ''Paraentelodon'' is derived from the Greek ''para''/παρα "beside" or "near", ἐντελής entel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entelodon
''Entelodon'' (meaning "complete teeth", from Ancient Greek ''entelēs'' "complete" and ''odōn'' "tooth", referring to its "complete" eutherian dentition), is an extinct genus of entelodont artiodactyl endemic to Eurasia. Fossils of species are found in Paleogene strata ranging in age from the Houldjinian (37.2–33.9 mya) until the Rupelian epoch of the early Oligocene (33.9–28.4 mya). Taxonomy It is one of four entelodont genera native to Eurasia, the other three being the primitive ''Eoentelodon'' of late Eocene China, '' Proentelodon'' of middle Eocene Mongolia and the gigantic ''Paraentelodon'' of mid to late Oligocene Central Asia. Description ''Entelodon'' was a fairly typical entelodont, with a large, bulky body, slender legs, and a long snout. Like other entelodonts, ''Entelodon'' had complete eutherian dentition (3 incisors, 1 canine, 3 premolars, and 3 molars per quadrant). It had only two toes on each foot, and its legs were built for fast running.Agustí, J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope Carbon-13, 13C in the atmosphere was exceptionally low in comparison with the more common isotope Carbon-12, 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Popigai impact structure, Siberia and in what is now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphology (biology)
Morphology is a branch of biology dealing with the study of the form and structure of organisms and their specific structural features. This includes aspects of the outward appearance (shape, structure, colour, pattern, size), i.e. external morphology (or eidonomy), as well as the form and structure of the internal parts like bones and organs, i.e. internal morphology (or anatomy). This is in contrast to physiology, which deals primarily with function. Morphology is a branch of life science dealing with the study of gross structure of an organism or taxon and its component parts. History The etymology of the word "morphology" is from the Ancient Greek (), meaning "form", and (), meaning "word, study, research". While the concept of form in biology, opposed to function, dates back to Aristotle (see Aristotle's biology), the field of morphology was developed by Johann Wolfgang von Goethe (1790) and independently by the German anatomist and physiologist Karl Friedrich Burdach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sagittal Crest
A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptionally strong jaw muscles. The sagittal crest serves primarily for attachment of the temporalis muscle, which is one of the main chewing muscles. Development of the sagittal crest is thought to be connected to the development of this muscle. A sagittal crest usually develops during the juvenile stage of an animal in conjunction with the growth of the temporalis muscle, as a result of convergence and gradual heightening of the temporal lines. Function A sagittal crest tends to be present on the skulls of adult animals that rely on powerful biting and clenching of their teeth, usually as a part of their hunting strategy. Skulls of some dinosaur species, including tyrannosaurs, possessed well developed sagittal crests. Among mammals, dogs, cats, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temporal Fossa
The temporal fossa is a fossa (shallow depression) on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch. Boundaries * Medial: frontal bone, parietal bone, temporal bone, and sphenoid bone. * Lateral: Temporal fascia * Anterior: Posterior surface of the frontal process of the zygomatic bone and the posterior surface of the zygomatic process of the frontal bone. * Superior: Pair of temporal lines (superior and inferior temporal lines) that arch across the skull from the zygomatic process of the frontal bone to the supramastoid crest of the temporal bone * Inferior: Zygomatic arch laterally and by the infratemporal crest of the greater wing of the sphenoid medially. Temporal & Infratemporal Fossa * Osteology * Temporal fossa, boundaries & contents * Infratemporal fossa, boundaries & contents * Muscles of mastication * Maxillary artery * Pterygoid venous plexus * Mandibular nerve * Temporomandibular Joint Contents * Tempo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postorbital Bar
The postorbital bar (or postorbital bone) is a bony arched structure that connects the frontal bone of the skull to the zygomatic arch, which runs laterally around the eye socket. It is a trait that only occurs in mammalian taxa, such as most strepsirrhine primates and the hyrax, while haplorhine primates have evolved fully enclosed sockets. One theory for this evolutionary difference is the relative importance of vision to both orders. As haplorrhines (tarsiers and simians) tend to be diurnal, and rely heavily on visual input, many strepsirrhines are nocturnal and have a decreased reliance on visual input. Postorbital bars evolved several times independently during mammalian evolution and the evolutionary histories of several other clades. Some species, such as Tarsiers, have a postorbital septum. This septum can be considered as joined processes with a small articulation between the frontal bone, the zygomatic bone and the alisphenoid bone and is therefore different from the posto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movable bone of the skull (discounting the ossicles of the middle ear). It is connected to the temporal bones by the temporomandibular joints. The bone is formed prenatal development, in the fetus from a fusion of the left and right mandibular prominences, and the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, p. 59 The word "mandible" derives from the Latin word ''mandibula'', "jawbone" (literally "one used for chewing"), from ''wikt:mandere ... [...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] |
Zygomatic Arch
In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygomatic bone (the side of the cheekbone), the two being united by an oblique suture (the zygomaticotemporal suture); the tendon of the temporal muscle passes medial to (i.e. through the middle of) the arch, to gain insertion into the coronoid process of the mandible (jawbone). The jugal point is the point at the anterior (towards face) end of the upper border of the zygomatic arch where the masseteric and maxillary edges meet at an angle, and where it meets the process of the zygomatic bone. The arch is typical of '' Synapsida'' (“fused arch”), a clade of amniotes that includes mammals and their extinct relatives, such as ''Moschops'' and '' Dimetrodon''. Structure The zygomatic process of the temporal arises by two roots: * an ''anter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Jugal Bone")
