Proboscidea is a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. Three species of elephant are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant.
Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine teeth, as with narwhals, chevrotains, musk deer, water deer, muntjac, pigs, peccaries, hippopotamuses and walruses, or, in the case of elephants, elongated incisors. Tusks share common features such as extra-oral position, growth pattern, composition and structure, and lack of contribution to ingestion. Tusks are thought to have adapted to the extra-oral environments, like dry or aquatic or arctic. In most tusked species both the males and the females have tusks although the males' are larger. Most mammals with tusks have a pair of them growing out from either side of the mouth. Tusks are generally curved and have a smooth, continuous surface. The male narwhal's straight single helical tusk, which usually grows out from the left of the mouth, is an exception to the typical features of tusks described above. Continuous growth of tusks is enabled by formative tissues in the apical openings of the roots of the teeth.
The African forest elephant is one of the two living species of African elephant. It is native to humid tropical forests in West Africa and the Congo Basin. It is the smallest of the three living elephant species, reaching a shoulder height of 2.4 m. As with other African elephants, both sexes have straight, down-pointing tusks, which begin to grow once the animals reach 1–3 years old. The forest elephant lives in highly sociable family groups of up to 20 individuals. Since they forage primarily on leaves, seeds, fruit, and tree bark, they have often been referred to as the 'megagardener of the forest'; the species is one of many that contributes significantly to maintaining the composition, diversity and structure of the Guinean Forests of West Africa and the Congolese rainforests. Seeds of various plants will go through the elephant's digestive tract and eventually pass through in the animal's droppings, thus helping to maintain the spread and biodiversity of the forests.
Incisors are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight. Opossums have 18, whereas armadillos have none.
Coleoidea or Dibranchiata is one of the two subclasses of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less". Unlike its extant sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal shell called cuttlebone or gladius that is used for buoyancy or as muscle anchorage. Some species, notably incirrate octopuses, have lost their internal shell altogether, while in some it has been replaced by a chitinous support structure.
African elephants are members of the genus Loxodonta comprising two living elephant species, the African bush elephant and the smaller African forest elephant. Both are social herbivores with grey skin. However, they differ in the size and colour of their tusks as well as the shape and size of their ears and skulls.
The tusk shells or tooth shells, technically the Scaphopoda, are members of a class of shelled marine mollusc with worldwide distribution, and are the only class of exclusively infaunal marine molluscs. Shells of species within this class range in length 0.5–18 cm (0.20–7.09 in). Members of the order Dentaliida tend to be larger than those of the order Gadilida.
Shell money is a medium of exchange similar to coin money and other forms of commodity money, and was once commonly used in many parts of the world. Shell money usually consisted of whole or partial sea shells, often worked into beads or otherwise shaped. The use of shells in trade began as direct commodity exchange, the shells having use-value as body ornamentation. The distinction between beads as commodities and beads as money has been the subject of debate among economic anthropologists.
The Columbian mammoth is an extinct species of mammoth that inhabited North America from southern Canada to Costa Rica during the Pleistocene epoch. The Columbian mammoth descended from Eurasian steppe mammoths that colonised North America during the Early Pleistocene around 1.5–1.3 million years ago, and later experienced hybridisation with the woolly mammoth lineage. The Columbian mammoth was among the last mammoth species, and the pygmy mammoths evolved from them on the Channel Islands of California. The closest extant relative of the Columbian and other mammoths is the Asian elephant.
The giant forest hog, the only member of its genus (Hylochoerus), is native to wooded habitats in Africa and is one of the largest wild members of the pig family, Suidae, along with a few subspecies of the wild boar. It was first described in 1904. The specific name honours Richard Meinertzhagen, who shot the type specimen in Kenya and had it shipped to the Natural History Museum in England.
The straight-tusked elephant is an extinct species of elephant that inhabited Europe and Western Asia during the Middle and Late Pleistocene. One of the largest known elephant species, mature fully grown bulls on average had a shoulder height of 4 metres (13 ft) and a weight of 13 tonnes (29,000 lb). Straight-tusked elephants likely lived very similarly to modern elephants, with herds of adult females and juveniles and solitary adult males. The species was primarily associated with temperate and Mediterranean woodland and forest habitats, flourishing during interglacial periods, when its range would extend across Europe as far north as Great Britain and eastwards into Russia. Skeletons found in association with stone tools and wooden spears suggest they were scavenged and hunted by early humans, including Neanderthals. It is the ancestor of most dwarf elephants that inhabited islands in the Mediterranean.
Imagotaria is an extinct monotypic genus of walrus with the sole species Imagotaria downsi. Fossils of Imagotaria are known from the early late Miocene of California.
Odobenocetops is an extinct genus of small toothed whale known from Chile and Peru. Its fossils are found in Miocene-aged marine strata of the Bahía Inglesa Formation and Pisco Formation. Two species of Odobenocetops are currently recognized, O. peruvianus and the slightly younger O. leptodon.
The word dentalium, as commonly used by Native American artists and anthropologists, refers to tooth shells or tusk shells used in indigenous jewelry, adornment, and commerce in western Canada and the United States. These tusk shells are a kind of seashell, specifically the shells of scaphopod mollusks. The name "dentalium" is based on the scientific name for the genus Dentalium, but because the taxonomy has changed over time, not all of the species used are still placed in that genus; however, all of the species are certainly in the family Dentaliidae.
Dentalium neohexagonum is a species of tusk shell, a marine scaphopod mollusk in the family Dentaliidae. As the Latin name implies, the cross section of this shell is hexagonal; hence its common name is six-sided tusk shell.
Metaxytherium is an extinct genus of dugong that lived from the Oligocene until the end of the Pliocene. Fossil remains have been found in Africa, Europe, North America and South America. Generally marine seagrass specialists, they inhabited the warm and shallow waters of the Paratethys, Mediterranean, Caribbean Sea and Pacific coastline. American species of Metaxytherium are considered to be ancestral to the North Pacific family Hydrodamalinae, which includes the giant Steller's sea cow.
Dentalium is a large genus of tooth shells or tusk shells, marine scaphopod molluscs in the family Dentaliidae. The genus contains 50 described species and about 50 extinct species.
Pteropurpura festiva, commonly known as the festive murex, is a species of predatory sea snail, a marine gastropod mollusk in the family Muricidae, the rock snails. Native to the Eastern Pacific, these sea snails grow to 34–67 mm in length.
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.
Antalis pretiosa, commonly known as the Wampum tuskshell or the Indian money tusk is a species of tusk shell in the family Dentaliidae. It was first described by George Brettingham Sowerby II, and named by Thomas Nuttall in 1860.
