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Osodobenus
''Osodobenus'' is an extinct genus of walrus from the Miocene to Pliocene of California. ''Osodobenus'' may have been the first tusked walrus and shows several adaptations that suggest it was a suction feeder, possibly even a benthic feeder like modern species. Three skulls are known showing pronounced sexual dimorphism, with the female lacking the same tusks as the male. Only a single species, ''Osodobenus eodon'', is currently recognized. Discovery and naming ''Osodobenus'' is known from three specimens including an adult male, adult female and a juvenile specimen preserving skulls and some postcranial material. All the material was collected from the Late Miocene to Early Pliocene (Messinian to Zanclean) Capistrano Formation, Orange County, California alongside the remains of several other early odobenids. In 2020, Biewer and colleagues published a detailed description of the material, establishing ''Osodobenus'' as a new genus while also erecting two new species of ''Pontol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capistrano Formation
The Capistrano Formation is a geologic formation in coastal southern Orange County, California. It preserves fossils dating back to the late Miocene to early Pliocene, with the Oso Member representing a near-shore environment. Fifty-nine species and varieties of foraminifera are recognized from the Capistrano Formation alongside a diverse array of marine mammals including up to five species of walrus. Geography The Capistrano Formation, named for the town of San Juan Capistrano, is located in southern California, specifically the northern extent of the Peninsular Ranges, which stretch from the Los Angeles Basin to Baja California. It crops out along the coast from Dana Point to San Clemente, and inland for seven miles. Geology and Stratigraphy The Capistrano Formation is a heterogenous marine formation that can be differentiated into two distinct but adjacent units. One of these units is the Oso Member, which is composed of arkosic sandstone and preserves a nearshore environ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" because it has 18% fewer modern marine invertebrates than the Pliocene has. The Miocene followed the Oligocene and preceded the Pliocene. As Earth went from the Oligocene through the Miocene and into the Pliocene, the climate slowly cooled towards a series of ice ages. The Miocene boundaries are not marked by distinct global events but by regionally defined transitions from the warmer Oligocene to the cooler Pliocene Epoch. During the Early Miocene, Afro-Arabia collided with Eurasia, severing the connection between the Mediterranean and Indian Oceans, and allowing the interchange of fauna between Eurasia and Africa, including the dispersal of proboscideans and Ape, hominoids into Eurasia. During the late Miocene, the conn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasal Bones
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Each has two surfaces and four borders. Structure There is heavy variation in the structure of the nasal bones, accounting for the differences in sizes and shapes of the nose seen across different people. Angles, shapes, and configurations of both the bone and cartilage are heavily varied between individuals. Broadly, most nasal bones can be categorized as "V-shaped" or "S-shaped" but these are not scientific or medical categorizations. When viewing anatomical drawings of these bones, consider that they are unlikely to be accurate for a majority of people. The two nasal bones are joined at the midline internasal suture and make up the bridge of the nose. Surfaces The ''outer surface'' is concavo-convex from above downward, convex from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kamtschatarctos
''Kamtschatarctos'' is an extinct genus of pinniped that lived approximately 15.97 to 11.608 mya during the Early Miocene in the Kavran-Ukhtolok Bay of Russia's Kamchatka Peninsula. It belonged to the family Odobenidae, the only extant species of which is the walrus The walrus (''Odobenus rosmarus'') is a large pinniped marine mammal with discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. It is the only extant species in the family Odobeni .... Discovery ''Kamtschatarctos sinelnikovae'' is known from a partially complete skeleton, discovered in the Etolon Formation in Russia. Taxonomy ''Kamtschatarctos'' is a relatively basal species of odobenid. References Pinnipeds of Europe Odobenids Prehistoric pinnipeds Monotypic prehistoric carnivoran genera {{paleo-carnivora-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neotherium
''Neotherium mirum'' is an extinct species of basal walrus. It was smaller than living forms and it did not have long tusks. Males were larger than females. Palaeoecology Stable isotope evidence indicates that in the eastern North Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the contine ..., ''Neotherium'' had intermediate foraging habits between the nearshore specialist '' Pithanotaria'' and the offshore specialist '' Allodesmus''. References Miocene pinnipeds Monotypic prehistoric carnivoran genera Miocene mammals of North America Miocene mammals of Asia Odobenids Fossil taxa described in 1931 Taxa named by Remington Kellogg {{Paleo-carnivora-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proneotherium
''Proneotherium'' is an extinct genus of pinniped that lived approximately 20.43 to 15.97 mya during the Early Miocene in what is now Oregon, U.S. It belonged to the family Odobenidae, the only extant species of which is the walrus. Discovery Four specimens of ''Proneotherium'' were discovered in the Astoria Formation of Lincoln County, Oregon, U.S. These specimens included cranial and postcranial remains and are all believed to be adult male animals. Description ''Proneotherium'' was more similar in appearance to modern fur seals and sea lions than walruses. They lacked the long tusks of walruses, and were more slender and smaller than their modern relatives. Autapomorphies of ''Proneotherium'' fossils include a continuous, horizontal crest connecting the mastoid and paroccipital processes of the skull. The teeth are also less secodont in function and appearance than more basal species. This likely represents the slow shift from a piscivorous diet to the mollusk-based diet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prototaria
''Prototaria'' is an extinct genus of pinniped that lived approximately 15.97 to 13.65 mya during the Middle Miocene in what is now Japan. It belonged to the family Odobenidae, the only extant species of which is the walrus. Members of the genus ''Prototaria'' are believed to be the most basal imagotariine pinnipeds. Unlike their closest living relative, the walrus, members of ''Prototaria'' were primarily piscivorous carnivores. Description ''Prototaria'' were more similar in appearance to modern fur seals and sea lions than walruses. They did not have long tusks as walruses do, and were more slender. Fossils ascribed to ''Prototaria'' exhibit some autapomorphies, including: a large antorbital process and orbit, and a relatively narrow intertemporal region of the skull. ''P. planicephala'' has a wider rostrum than ''P. primigena'' as well as more specialized cheek teeth and a flatter tympanic bulla The tympanic part of the temporal bone is a curved plate of bone lying belo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodobenia
Odobenidae is a family of pinnipeds, of which the only extant species is the walrus (''Odobenus rosmarus''). In the past, however, the group was much more diverse, and includes more than a dozen fossil genera. Taxonomy All genera, except ''Odobenus'', are extinct. *†''Archaeodobenus'' *†''Prototaria'' *†''Proneotherium'' *†''Nanodobenus'' *†''Neotherium'' *†''Imagotaria'' *†''Kamtschatarctos'' *†''Pelagiarctos'' *†''Pontolis'' *†'' Pseudotaria'' *†''Titanotaria'' *Clade Neodobenia **†'' Gomphotaria'' **Subfamily Dusignathinae ***†'' Dusignathus'' **Subfamily Odobeninae ***†'' Aivukus'' ***†''Ontocetus'' ***†'' Pliopedia'' ***†'' Protodobenus'' ***†'' Valenictus'' ***''Odobenus The walrus (''Odobenus rosmarus'') is a large pinniped marine mammal with discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. It is the only extant species in the family Odobenida ...'' In re-analyzin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tortonian
The Tortonian is in the geologic time scale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma (million years ago). It follows the Serravallian and is followed by the Messinian. The Tortonian roughly overlaps with the regional Pannonian Stage of the Paratethys timescale of Central Europe. It also overlaps the upper Astaracian, Vallesian and lower Turolian European land mammal ages, the upper Clarendonian and lower Hemphillian North American land mammal ages and the upper Chasicoan and lower Huayquerian South American land mammal ages. Definition The Tortonian was introduced by Swiss stratigrapher Karl Mayer-Eymar in 1858. It was named after the Italian city of Tortona in the Piedmont region. The base of the Tortonian Stage is at the last common appearance of calcareous nanoplankton '' Discoaster kugleri'' and planktonic foram '' Globigerinoides subquadratus''. It is also associated with the short normal pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexually Dimorphic
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, dioecious species, which consist of most animals and some plants. Differences may include secondary sex characteristics, size, weight, color, markings, or behavioral or cognitive traits. Male-male reproductive competition has evolved a diverse array of sexually dimorphic traits. Aggressive utility traits such as "battle" teeth and blunt heads reinforced as battering rams are used as weapons in aggressive interactions between rivals. Passive displays such as ornamental feathering or song-calling have also evolved mainly through sexual selection. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', when both biological sexes are phenotype, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulp (tooth)
The pulp is the connective tissue, nerves, blood vessels, and odontoblasts that comprise the innermost layer of a tooth. The pulp's activity and signalling processes regulate its behaviour. Anatomy The pulp is the neurovascular bundle central to each tooth, permanent tooth, permanent or primary tooth, primary. It is composed of a central pulp chamber, pulp horns, and radicular canals. The large mass of the pulp is contained within the pulp chamber, which is contained in and mimics the overall shape of the crown of the tooth.Fehrenbach, MJ. and Popowics, T. (2026), ''Illustrated Dental Embryology, Histology, and Anatomy'', Elsevier, page 185-86. Because of the continuous deposition of the dentine, the pulp chamber becomes smaller with the age. This is not uniform throughout the coronal pulp but progresses faster on the floor than on the roof or sidewalls. Radicular pulp canals extend down from the cervical region of the crown to the Root apex (dental), root apex. They are not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canine (tooth)
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, eye teeth, vampire teeth, or fangs, are the relatively long, pointed teeth. In the context of the upper jaw, they are also known as '' fangs''. They can appear more flattened, however, causing them to resemble incisors and leading them to be called ''incisiform''. They developed and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons. They are often the largest teeth in a mammal's mouth. Individuals of most species that develop them normally have four, two in the upper jaw and two in the lower, separated within each jaw by incisors; humans and dogs are examples. In most species, canines are the anterior-most teeth in the maxillary bone. The four canines in humans are the two upper maxillary canines and the two lower mandibular canines. They are specially prominent in dogs (Canidae), hence the name. Details There are generally four canine teeth: two i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
