Archaeodobenus is an extinct genus of pinniped that lived during the Late Miocene of what is now Japan. It belonged to the Odobenidae family, today only represented by the walrus, but was much more diverse in the past, containing at least 16 genera. Unlike the modern walrus, Archaeodobenus did not have tusks but instead had canines of moderate size, looked more like a sea lion; the first known specimen was collected in 1977 from the Ichibangawa Formation in Tobetsu Town on the island of Hokkaido. The specimen consists of a partial skull and limb bones, was made the holotype specimen of the new genus and species A. akamatsui by the Japanese palaeontologists Yoshihiro Tanaka and Naoki Kohno in 2015. The generic name consists of archaio, the Greek word for ancient, the generic name of the walrus, Odobenus; the specific name honours a curator of the Hokkaido Museum. The diversity of odobenids increased during the Late Miocene and Pliocene linked to marine regression and transgression, which could have geographically isolated their ancestors.
Archaeodobenus was the contemporary of the odobenid Pseudotaria from the same formation, which it may have diverged from in the western North Pacific during the Late Miocene. Archaeodobenus appears to have been closer related to odobenids such as Imagotaria, the subfamily Odobeninae, whereas Pseudotaria seems to have been more basal; the holotype specimen appears to have been a young adult male of about 3 metres in length, which would have weighed around 473 kg. This is intermediate between the size of the South American sea lion, its canines were 86.3 mm long. Archaeodobenus can be distinguished from Pseudotaria by features such as the shape and size of the occipital condyle, the foramen magnum, the mastoid process, as well as some features in the postcranial skeleton
Pinnipeds known as seals, are a distributed and diverse clade of carnivorous, fin-footed, semiaquatic marine mammals. They comprise the extant families Odobenidae and Phocidae. There are 33 extant species of pinnipeds, more than 50 extinct species have been described from fossils. While seals were thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage. Pinnipeds belong to the order Carnivora and their closest living relatives are believed to be bears and the superfamily of musteloids, having diverged about 50 million years ago. Seals range in size from the 1 m and 45 kg Baikal seal to the 5 m and 3,200 kg southern elephant seal, the largest member of the order Carnivora. Several species exhibit sexual dimorphism, they have four limbs that are modified into flippers. Though not as fast in the water as dolphins, seals are more agile. Otariids use their front limbs to propel themselves through the water, while phocids and walruses use their hind limbs.
Otariids and walruses have hind limbs that can be used as legs on land. By comparison, terrestrial locomotion by phocids is more cumbersome. Otariids have visible external ears, while walruses lack these. Pinnipeds have well-developed senses—their eyesight and hearing are adapted for both air and water, they have an advanced tactile system in their whiskers or vibrissae; some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water, other than the walrus, all species are covered in fur. Although pinnipeds are widespread, most species prefer the colder waters of the Northern and Southern Hemispheres, they spend most of their lives in the water, but come ashore to mate, give birth, molt or escape from predators, such as sharks and killer whales. They feed on fish and marine invertebrates. Walruses are specialized for feeding on bottom-dwelling mollusks. Male pinnipeds mate with more than one female, although the degree of polygyny varies with the species.
The males of land-breeding species tend to mate with a greater number of females than those of ice breeding species. Male pinniped strategies for reproductive success vary between defending females, defending territories that attract females and performing ritual displays or lek mating. Pups are born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a short period of time while others take foraging trips at sea between nursing bouts. Walruses are known to nurse their young while at sea. Seals produce a number of vocalizations, notably the barks of California sea lions, the gong-like calls of walruses and the complex songs of Weddell seals; the meat and fur coats of pinnipeds have traditionally been used by indigenous peoples of the Arctic. Seals have been depicted in various cultures worldwide, they are kept in captivity and are sometimes trained to perform tricks and tasks. Once relentlessly hunted by commercial industries for their products and walruses are now protected by international law.
The Japanese sea lion and the Caribbean monk seal have become extinct in the past century, while the Mediterranean monk seal and Hawaiian monk seal are ranked endangered by the International Union for Conservation of Nature. Besides hunting, pinnipeds face threats from accidental trapping, marine pollution, conflicts with local people; the German naturalist Johann Karl Wilhelm Illiger was the first to recognize the pinnipeds as a distinct taxonomic unit. American zoologist Joel Asaph Allen reviewed the world's pinnipeds in an 1880 monograph, History of North American pinnipeds, a monograph of the walruses, sea-lions, sea-bears and seals of North America. In this publication, he traced the history of names, gave keys to families and genera, described North American species and provided synopses of species in other parts of the world. In 1989, Annalisa Berta and colleagues proposed the unranked clade Pinnipedimorpha to contain the fossil genus Enaliarctos and modern seals as a sister group. Pinnipeds belong to the suborder Caniformia.
Pinnipedia was considered its own suborder under Carnivora. Of the three extant families, the Otariidae and Odobenidae are grouped in the superfamily Otarioidea, while the Phocidae belong to the superfamily Phocoidea. Otariids are known as eared seals due to the presence of pinnae; these animals rely on their well-developed fore-flippers to propel themselves through the water. They can turn their hind-flippers forward and "walk" on land; the anterior end of an otariid's frontal bones extends between the nasal bones, the supraorbital foramen is large and flat horizontally. The supraspinatous fossas are divided by a "secondary spine" and the bronchi are divided anteriorly. Otariids consist of two types: fur seals. Sea lions are distinguished by their rounder snouts and shorter, rougher pelage, while fur seals have more pointed snouts, longer fore-flippers and thicker fur coats that include an undercoat and guard hairs; the former tend to be larger than the latter. Five genera and seven species of
Carnivora is a diverse scrotiferan order that includes over 280 species of placental mammals. Its members are formally referred to as carnivorans, whereas the word "carnivore" can refer to any meat-eating organism. Carnivorans are the most diverse in size of any mammalian order, ranging from the least weasel, at as little as 25 g and 11 cm, to the polar bear, which can weigh up to 1,000 kg, to the southern elephant seal, whose adult males weigh up to 5,000 kg and measure up to 6.7 m in length. Carnivorans have teeth and claws adapted for catching and eating other animals. Many hunt in are social animals, giving them an advantage over larger prey; some carnivorans, such as cats and pinnipeds, depend on meat for their nutrition. Others, such as raccoons and bears, are more omnivorous, depending on the habitat; the giant panda is a herbivore, but feeds on fish and insects. The polar bear subsists on seals. Carnivorans are split into two suborders: Caniformia. Carnivorans all share the same arrangement of teeth in which the last upper premolar and the first lower molar have blade-like enamel crowns that work together as carnassial teeth to shear meat.
Carnivorans have had this arrangement for over 60 million years with many adaptions, these dental adaptions help identify carnivoran species and groupings of species. Carnivorans evolved in North America out of members of the family Miacidae about 42 million years ago, they soon split into dog-like forms. Their molecular phylogeny shows the extant Carnivora are a monophyletic group, the crown group of the Carnivoramorpha. Most carnivorans are terrestrial; the last premolar of the upper jaw and first molar of the lower are termed the carnassials or sectorial teeth. These blade-like teeth occlude with a scissor-like action for shredding meat. Carnassials are most developed in the Felidae and the least developed in the Ursidae. Carnivorans have two conical canines in each jaw; the only two exceptions to this are the sea otter, which has four incisors in the lower jaw, the sloth bear, which has four incisors in the upper jaw. The number of molars and premolars is variable between carnivoran species, but all teeth are rooted and are diphyodont.
Incisors are retained by carnivorans and the third incisor is large and sharp. Carnivorans have either four or five digits on each foot, with the first digit on the forepaws known as the dew claw, being vestigial in most species and absent in some; the superfamily Canoidea – Canidae, Mustelidae, Ursidae, Otariidae and Phocidae and the extinct family Amphicyonidae – are characterized by having nonchambered or chambered auditory bullae, nonretractable claws, a well-developed baculum. Most species are rather plain in coloration, lacking the flashy spotted or rosetted coats like many species of felids and viverrids have; this is because Canoidea tend to range in the temperate and subarctic biomes, although Mustelidae and Procyonidae have a few tropical species. Most are terrestrial. All families except the Canidae and a few species of Mustelidae are plantigrade. Diet is varied and most tend to be omnivorous to some degree, thus the carnassial teeth are less specialized. Canoidea have more molars in an elongated skull.
The superfamily Feloidea – Felidae, Herpestidae, Hyaenidae and Eupleridae, as well as the extinct family Nimravidae – have spotted, rosetted or striped coats, tend to be more brilliantly colored than their Canoidean counterparts. This is because these species tend to range in tropical habitats, although a few species do inhabit temperate and subarctic habitats. Many are arboreal or semiarboreal, the majority are digitigrade. Diet tends to be more carnivorous in the family Felidae, they have fewer teeth and shorter skulls, with much more specialized carnassials meant for shearing meat. Feliformia claws are retractile, or semiretractile; the terminal phalanx, with the claw attached, folds back in the forefoot into a sheath by the outer side of the middle phalanx of the digit, is retained in this position when at rest by a strong elastic ligament. In the hindfoot, the terminal joint or phalanx is retracted on to the top, not the side of the middle phalanx. Deep flexor muscles straighten the terminal phalanges, so the claws protrude from their sheaths, the soft "velvety" paw becomes converted into a formidable weapon.
The habitual retraction of the claws preserves their points from wear. The superfamily Pinnipedia, now considered to be part of Caniformia, are medium to large aquatic mammals. Being homeothermic marine mammals, pinni
The walrus is a large flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in the family genus Odobenus; this species is subdivided into three subspecies: the Atlantic walrus which lives in the Atlantic Ocean, the Pacific walrus which lives in the Pacific Ocean, O. r. laptevi, which lives in the Laptev Sea of the Arctic Ocean. Adult walrus are recognized by their prominent tusks and bulk. Adult males in the Pacific can weigh more than 2,000 kg and, among pinnipeds, are exceeded in size only by the two species of elephant seals. Walruses live in shallow waters above the continental shelves, spending significant amounts of their lives on the sea ice looking for benthic bivalve mollusks to eat. Walruses are long-lived, social animals, they are considered to be a "keystone species" in the Arctic marine regions; the walrus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted the walrus for its meat, skin and bone.
During the 19th century and the early 20th century, walruses were hunted and killed for their blubber, walrus ivory, meat. The population of walruses dropped all around the Arctic region, their population has rebounded somewhat since though the populations of Atlantic and Laptev walruses remain fragmented and at low levels compared with the time before human interference. The origin of the word walrus is thought by J. R. R. Tolkien to derive from a Germanic language, it has been attributed to either the Dutch language or Old Norse, its first part is thought to derive from a word such as Dutch walvis'whale'. Its second part has been hypothesized to come from the Old Norse word for'horse'. For example, the Old Norse word hrossvalr means'horse-whale' and is thought to have been passed in an inverted form to both Dutch and the dialects of northern Germany as walros and Walross. An alternative theory is that it comes from the Dutch words wal'shore' and reus'giant'; the species name rosmarus is Scandinavian.
The Norwegian manuscript Konungsskuggsja, thought to date from around AD 1240, refers to the walrus as "rosmhvalr" in Iceland and "rostungr" in Greenland. Several place names in Iceland and Norway may originate from walrus sites: Hvalfjord and Hvalsnes to name some, all being typical walrus breeding grounds; the archaic English word for walrus—morse—is thought to have come from the Slavic languages, which in turn borrowed it from Finno-Ugric languages. Compare морж in Russian, mursu in Finnish, morša in Northern Saami, morse in French. Olaus Magnus, who depicted the walrus in the Carta Marina in 1539, first referred to the walrus as the ros marus a Latinization of morž, this was adopted by Linnaeus in his binomial nomenclature; the coincidental similarity between morse and the Latin word morsus contributed to the walrus's reputation as a "terrible monster". The compound Odobenus comes from odous and baino, based on observations of walruses using their tusks to pull themselves out of the water.
The term divergens in Latin means ` referring to their tusks. The walrus is a mammal in the order Carnivora, it is the sole surviving member of the family Odobenidae, one of three lineages in the suborder Pinnipedia along with true seals and eared seals. While there has been some debate as to whether all three lineages are monophyletic, i.e. descended from a single ancestor, or diphyletic, recent genetic evidence suggests all three descended from a caniform ancestor most related to modern bears. Recent multigene analysis indicates the odobenids and otariids diverged from the phocids about 20–26 million years ago, while the odobenids and the otariids separated 15–20 million years ago. Odobenidae was once a diverse and widespread family, including at least twenty species in the subfamilies Imagotariinae and Odobeninae; the key distinguishing feature was the development of a squirt/suction feeding mechanism. Two subspecies of walrus are recognized: the Atlantic walrus, O. r. rosmarus and the Pacific walrus, O. r. divergens.
Fixed genetic differences between the Atlantic and Pacific subspecies indicate restricted gene flow, but recent separation, estimated at 500,000 and 785,000 years ago. These dates coincide with the hypothesis derived from fossils that the walrus evolved from a tropical or subtropical ancestor that became isolated in the Atlantic Ocean and adapted to colder conditions in the Arctic. From there, it recolonized the North Pacific Ocean during high glaciation periods in the Pleistocene via the Central American Seaway. An isolated population in the Laptev Sea is considered by some authorities, including many Russian biologists and the canonical Mammal Species of the World, to be a third subspecies, O. r. laptevi, is managed as such in Russia. Where the subspecies separation is not accepted, whether to consider it a subpopulation of the Atlantic or Pacific subspecies remained under debate until 2009, when multiple lines of molecular evidence showed it to represent the westernmost population of the Pacific walrus.
While some outsized Pacific males can weigh as much as 2,000 kg, most weigh between 800 and 1,700 kg. An occasiona
Fossilworks is a portal which provides query and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. Fossilworks is housed at Macquarie University, it includes many analysis and data visualization tools included in the Paleobiology Database. "Fossilworks". Retrieved 2010-04-08
Aivukus is an extinct genus of walrus from the Miocene. The generic name is derived from the Inuit word for aivuk. From fossil records it was at least as big as, if not bigger than, the modern walrus, like the modern walrus, was a molluscivore. Marine Mammals: Evolutionary Biology by Annalisa Berta, James L. Sumich Encyclopedia of Marine Mammals by William F. Perrin, Bernd Wursig, J. G. M. Thewissen
Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species. Jimmy Wales stated that editors are not required to fax in their degrees, but that submissions will have to pass muster with a technical audience. Wikispecies is available under the GNU Free Documentation License and CC BY-SA 3.0. Started in September 2004, with biologists across the world invited to contribute, the project had grown a framework encompassing the Linnaean taxonomy with links to Wikipedia articles on individual species by April 2005. Benedikt Mandl co-ordinated the efforts of several people who are interested in getting involved with the project and contacted potential supporters in early summer 2004. Databases were evaluated and the administrators contacted, some of them have agreed on providing their data for Wikispecies. Mandl defined two major tasks: Figure out how the contents of the data base would need to be presented—by asking experts, potential non-professional users and comparing that with existing databases Figure out how to do the software, which hardware is required and how to cover the costs—by asking experts, looking for fellow volunteers and potential sponsorsAdvantages and disadvantages were discussed by the wikimedia-I mailing list.
The board of directors of the Wikimedia Foundation voted by 4 to 0 in favor of the establishment of a Wikispecies. The project is hosted at species.wikimedia.org. It was merged to a sister project of Wikimedia Foundation on September 14, 2004. On October 10, 2006, the project exceeded 75,000 articles. On May 20, 2007, the project exceeded 100,000 articles with a total of 5,495 registered users. On September 8, 2008, the project exceeded 150,000 articles with a total of 9,224 registered users. On October 23, 2011, the project reached 300,000 articles. On June 16, 2014, the project reached 400,000 articles. On January 7, 2017, the project reached 500,000 articles. On October 30, 2018, the project reached 600,000 articles, a total of 1.12 million pages. Wikispecies comprises taxon pages, additionally pages about synonyms, taxon authorities, taxonomical publications, institutions or repositories holding type specimen. Wikispecies asks users to use images from Wikimedia Commons. Wikispecies does not allow the use of content.
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