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A diphyodont is any animal with two sets of teeth, initially the deciduous set and consecutively the permanent set. [1] [2] [3] Most mammals are diphyodonts—as to chew their food they need a strong, durable and complete set of teeth. Diphyodonts contrast with polyphyodonts, whose teeth are constantly replaced.
The number of teeth and their function can vary widely between species, with some dolphins having over a hundred teeth in their jaws, while the narwhal has two functional teeth in its upper jaw which grow into long tusks in males. The tusk is used in feeding, navigation and mating and contains millions of sensory pathways, making it the most ...
A polyphyodont is any animal whose teeth are continually replaced. In contrast, diphyodonts are characterized by having only two successive sets of teeth. [1] Polyphyodonts include most toothed fishes, many reptiles such as crocodiles and geckos, [2] [3] [4] and most other vertebrates, mammals being the main exception, though not absolute.
Like all sauropods, Nigersaurus was a quadruped with a small head, thick hind legs, and a prominent tail. Among that clade, Nigersaurus was fairly small, with a body length of only 9 m (30 ft) and a femur reaching only 1 m (3 ft 3 in); it may have weighed around 1.9–4 t (2.1–4.4 short tons), comparable to a modern elephant.
An African elephant in Tanzania, with visible tusks. 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.
True teeth are unique to vertebrates, [18] although some invertebrates have analogous structures sometimes called "teeth". The organism with the simplest genome bearing such "teeth" is probably the worm genus Ancylostoma (Ancylostoma duodenale, Necator americanus). [19] Molluscs have a structure called a radula which bears a ribbon of chitinous ...
(The largest two teeth of the top and bottom rows of teeth.) A fang is a long, pointed tooth. [1] In mammals, a fang is a modified maxillary tooth, used for biting and tearing flesh. In snakes, it is a specialized tooth that is associated with a venom gland (see snake venom). [2] Spiders also have external fangs, which are part of the chelicerae.
The recently extinct Steller's sea cow was the largest known sirenian to have lived, reaching lengths of 10 metres (33 feet) and weights of 5 to 10 tonnes (5.5 to 11.0 short tons). [2] Sirenians have a large, fusiform body which reduces drag through the water and heavy bones that act as ballast to counteract the buoyancy of their blubber. They ...