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The first bits were made of rope, bone, horn, or hard wood. Metal bits came into use between 1300 and 1200 BC, originally made of bronze. [8]: 17 In modern times, nickel was a favored material until about 1940, when stainless steel largely replaced it.
It was an animal approximately the size of a fox (250–450 mm in height), with a relatively short head and neck and a springy, arched back. It had 44 low-crowned teeth, in the typical arrangement of an omnivorous, browsing mammal: three incisors, one canine, four premolars, and three molars on each side of the jaw. Its molars were uneven, dull ...
[2] [3] Estimates on the number of Earth's current species range from 10 million to 14 million, [4] with about 1.2 million or 14% documented, the rest not yet described. [5] However, a 2016 report estimates an additional 1 trillion microbial species, with only 0.001% described. [6]
History of Animals (Ancient Greek: Τῶν περὶ τὰ ζῷα ἱστοριῶν, Ton peri ta zoia historion, "Inquiries on Animals"; Latin: Historia Animalium, "History of Animals") is one of the major texts on biology by the ancient Greek philosopher Aristotle. It was written in sometime between the mid-fourth century BC and Aristotle's ...
Today, humans possess 32 permanent teeth with a dental formula of 2.1.2.3 2.1.2.3. [1] This breaks down to two pairs of incisors, one pair of canines, two pairs of premolars, and three pairs of molars on each jaw. [1]
Carnivores possess diverse carnassial teeth. The carnassials are specialized teeth for different diets of different animals. [12] These teeth are used to cut through flesh. [12] Either the molars or both the premolars and molars in combination may be adapted into shearing carnassials. Tooth roots can be great indicators of diets.
The teeth were fully differentiated and the braincase bulged at the back of the head. Outside of some crown-group mammals (notably the therians ), all cynodonts probably laid eggs. The temporal fenestrae were much larger than those of their ancestors, and the widening of the zygomatic arch in a more mammal-like skull would have allowed for more ...
Dimetrodon (/ d aɪ ˈ m iː t r ə ˌ d ɒ n / ⓘ [1] or / d aɪ ˈ m ɛ t r ə ˌ d ɒ n /; [2] lit. ' two measures of teeth ') is an extinct genus of sphenacodontid synapsid tetrapods that lived during the Cisuralian age of the Early Permian period, around 295–272 million years ago.