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Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn in 1907 and is, although with many variations, the one that continues today. [1] [2] [3]
Source: [4]
| Name | Nomenclature term is used in | Definition | Comments | Image |
|---|---|---|---|---|
| Anterolingual conule | Reig (1977) [4] | A conule on the lingual side of an anterocone divided by an anteromedian flexus or fossette | ||
| Anteromedian flexus | Reig (1977) [4] | A longitudinal flexus dividing the anterocone into anterolabial and anterolingual conules | ||
| Anterolabial conule | Reig (1977) [4] | A conule on the labial side of an anterocone divided by an anteromedian flexus or fossette | ||
| Anterocone | Reig (1977) [4] | A cusp at the front of the tooth that may be divided into anterolabial and anterolingual conules | ||
| Protostyle | Reig (1977) [4] | A style in front of the protocone, in the protoflexus | ||
| Protoflexus | Reig (1977) [4] | A flexus between the protocone and the anterolingual conule | ||
| Anterior mure | Reig (1977) [4] | A crest connecting the anterocone to the protocone | ||
| Protocone | Reig (1977) [4] | One of the main cusps, at the anterolingual side | ||
| Enterostyle | Reig (1977) [4] | A style between the protocone and the hypocone, in the hypoflexus | ||
| Enteroloph | Reig (1977) [4] | A crest connecting the enterostyle to the mesocone | ||
| Hypoflexus | Reig (1977) [4] | A flexus between the protocone and the hypocone | ||
| Mesocone | Reig (1977) [4] | A conule in the median mure where the mesoloph is attached to it | ||
| Median mure | Reig (1977) [4] | A crest connecting the protocone/paracone to the hypocone/metacone | ||
| Hypocone | Reig (1977) [4] | One of the main cusps, at the posterolingual side | ||
| Procingulum | Reig (1977) [4] | The front part of the tooth, before the anterior mure | ||
| Anteroflexus | Reig (1977) [4] | A flexus between the anteroloph and the anterolabial conule | ||
| Anteroloph | Reig (1977) [4] | A crest between the paracone and the anterolabial conule that may be connecting to a parastyle | ||
| Parastyle | Reig (1977) [4] | A style in front of the paracone | ||
| Paraflexus | Reig (1977) [4] | A flexus in front of the paracone | ||
| Protolophule | Reig (1977) [4] | A small crest in the paraflexus, connected to the protocone | ||
| Paraloph | Reig (1977) [4] | A crest attaching the paracone to the protocone or the median mure | ||
| Paracone | Reig (1977) [4] | One of the main cusps, at the anterolabial side | ||
| Paralophule | Reig (1977) [4] | A small crest attached to the back side of the paracone | ||
| Mesoflexus | Reig (1977) [4] | A flexus between the mesoloph and the paracone | ||
| Mesostyle | Reig (1977) [4] | A style at the labial margin between the paracone and metacone | ||
| Mesoloph | Reig (1977) [4] | A crest in front of the metaflexus, connected to the median mure | ||
| Metaflexus | Reig (1977) [4] | A flexus in front of the metacone | ||
| Metalophule | Reig (1977) [4] | A small crest attached to the front side of the metacone | ||
| Metacone | Reig (1977) [4] | One of the main cusps, at the posterolabial side | ||
| Metaloph | Reig (1977) [4] | A crest attaching the paracone to the hypocone | ||
| Posteroflexus | Reig (1977) [4] | A flexus between the posteroloph and the metacone | ||
| Posterostyle | Reig (1977) [4] | A crest on the posterolabial corner of the molar | ||
| Posteroloph | Reig (1977) [4] | A crest at the back of the molar, connected to the hypocone |
| Name | Nomenclature term is used in | Definition | Comments | Image |
|---|---|---|---|---|
| Anterolingual conulid | Reig (1977) [4] | A conulid on the lingual side of an anteroconid divided by an anteromedian flexid or fossettid | ||
| Anteromedian flexid | Reig (1977) [4] | A longitudinal flexid dividing the anteroconid into anterolabial and anterolingual conules | ||
| Anterolabial conulid | Reig (1977) [4] | A conulid on the labial side of an anteroconid divided by an anteromedian flexid or fossettid | ||
| Anteroconid | Reig (1977) [4] | A cusp at the front of the tooth that may be divided into anterolabial and anterolingual conulids | ||
| Anterolabial cingulum | Reig (1977) [4] | A crest before the protoconid and protoflexid | ||
| Protostylid | Reig (1977) [4] | A stylid in front of the protoconid, in the protoflexid | ||
| Protoflexid | Reig (1977) [4] | A flexid between the protoconid and the anterolabial conulid | ||
| Anterior murid | Reig (1977) [4] | A crest connecting the anteroconid to the protoconid | ||
| Protoconid | Reig (1977) [4] | One of the main cusps, at the anterolabial side | ||
| Ectostylid | Reig (1977) [4] | A stylid between the protoconid and the hypoconid, in the hypoflexid | ||
| Ectolophid | Reig (1977) [4] | A crest connecting the ectostylid to the mesoconid | ||
| Hypoflexid | Reig (1977) [4] | A flexid between the protoconid and the hypoconid | ||
| Mesoconid | Reig (1977) [4] | A conulid in the median murid where the mesolophid is attached to it | ||
| Median murid | Reig (1977) [4] | A crest connecting the protoconid/metaconid to the hypoconid/entoconid | ||
| Hypoconid | Reig (1977) [4] | One of the main cusps, at the posterolabial side | ||
| Procingulum | Reig (1977) [4] | The front part of the tooth, before the anterior murid | ||
| Anteroflexid | Reig (1977) [4] | A flexid between the anterolophid and the anterolingual conulid | ||
| Anterolophid | Reig (1977) [4] | A crest between the metaconid and the anterolabial conulid that may be connecting to a metastylid | ||
| Metastylid | Reig (1977) [4] | A stylid in front of the metaconid | ||
| Metaflexid | Reig (1977) [4] | A flexid in front of the metaconid | ||
| Protolophulid | Reig (1977) [4] | A small crest in the mesoflexid, connected to the protoconid | ||
| Metalophid | Reig (1977) [4] | A crest attaching the metaconid to the protoconid or the anterior murid | ||
| Metaconid | Reig (1977) [4] | One of the main cusps, at the anterolingual side | ||
| Metalophulid | Reig (1977) [4] | A small crest attached to the back side of the metaconid | ||
| Mesoflexid | Reig (1977) [4] | A flexid between the mesolophid and the paraconid | ||
| Mesostylid | Reig (1977) [4] | A stylid at the labial margin between the metaconid and entoconid | ||
| Mesolophid | Reig (1977) [4] | A crest in front of the entoflexid, connected to the median murid | ||
| Entoflexid | Reig (1977) [4] | A flexid in front of the entoconid | ||
| Entolophulid | Reig (1977) [4] | A small crest attached to the front side of the entoconid | ||
| Entoconid | Reig (1977) [4] | One of the main cusps, at the posterolingual side | ||
| Entolophid | Reig (1977) [4] | A crest attaching the entoconid to the hypoconid or median murid | ||
| Posteroflexid | Reig (1977) [4] | A flexid between the posterolophid and the metaconid | ||
| Hypolophulid | Reig (1977) [4] | A small crest in the posteroflexid attached to the posterolophid | ||
| Posterostylid | Reig (1977) [4] | A crest on the posterolingual corner of the molar | ||
| Posterolophid | Reig (1977) [4] | A crest at the back of the molar, connected to the hypoconid |
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name molar derives from Latin, molaris dens, meaning "millstone tooth", from mola, millstone and dens, tooth. Molars show a great deal of diversity in size and shape across the mammal groups. The third molar of humans is sometimes vestigial.
In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, eye teeth, vampire teeth, or vampire 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.
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered transitional teeth during chewing, or mastication. They have properties of both the canines, that lie anterior and molars that lie posterior, and so food can be transferred from the canines to the premolars and finally to the molars for grinding, instead of directly from the canines to the molars.
The maxillary lateral incisors are a pair of upper (maxillary) teeth that are located laterally from both maxillary central incisors of the mouth and medially from both maxillary canines. As with all incisors, their function is for shearing or cutting food during mastication, commonly known as chewing. There are generally no cusps on the teeth, but the rare condition known as talon cusps are most prevalent on the maxillary lateral incisors. The surface area of the tooth used in eating is called an incisal ridge or incisal edge. Though relatively the same, there are some minor differences between the deciduous (baby) maxillary lateral incisor and that of the permanent maxillary lateral incisor. The maxillary lateral incisors occlude in opposition to the mandibular lateral incisors.
The mandibular second premolar is the tooth located distally from both the mandibular first premolars of the mouth but mesial from both mandibular first molars. The function of this premolar is assist the mandibular first molar during mastication, commonly known as chewing. Mandibular second premolars have three cusps. There is one large cusp on the buccal side of the tooth. The lingual cusps are well developed and functional. Therefore, whereas the mandibular first premolar resembles a small canine, the mandibular second premolar is more alike to the first molar. There are no deciduous (baby) mandibular premolars. Instead, the teeth that precede the permanent mandibular premolars are the deciduous mandibular molars.
The mandibular first molar or six-year molar is the tooth located distally from both the mandibular second premolars of the mouth but mesial from both mandibular second molars. It is located on the mandibular (lower) arch of the mouth, and generally opposes the maxillary (upper) first molars and the maxillary 2nd premolar in normal class I occlusion. The function of this molar is similar to that of all molars in regard to grinding being the principal action during mastication, commonly known as chewing. There are usually five well-developed cusps on mandibular first molars: two on the buccal, two lingual, and one distal. The shape of the developmental and supplementary grooves, on the occlusal surface, are described as being M-shaped. There are great differences between the deciduous (baby) mandibular molars and those of the permanent mandibular molars, even though their function are similar. The permanent mandibular molars are not considered to have any teeth that precede it. Despite being named molars, the deciduous molars are followed by permanent premolars.
Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. Tooth formation begins before birth, and the teeth's eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment.
A cusp is a pointed, projecting, or elevated feature. In animals, it is usually used to refer to raised points on the crowns of teeth. The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two cusps, is also known as the bicuspid valve, and the tricuspid valve has three cusps.
Ambondro mahabo is a mammal from the Middle Jurassic (Bathonian) Isalo III Formation of Madagascar. The only described species of the genus Ambondro, it is known from a fragmentary lower jaw with three teeth, interpreted as the last premolar and the first two molars. The premolar consists of a central cusp with one or two smaller cusps and a cingulum (shelf) on the inner, or lingual, side of the tooth. The molars also have such a lingual cingulum. They consist of two groups of cusps: a trigonid of three cusps at the front and a talonid with a main cusp, a smaller cusp, and a crest at the back. Features of the talonid suggest that Ambondro had tribosphenic molars, the basic arrangement of molar features also present in marsupial and placental mammals. It is the oldest known mammal with putatively tribosphenic teeth; at the time of its discovery it antedated the second oldest example by about 25 million years.
Brachytarsomys mahajambaensis is an extinct rodent from northwestern Madagascar. It is known from nine isolated molars found in several sites during fieldwork that started in 2001. First described in 2010, it is placed in the genus Brachytarsomys together with two larger living species, which may differ in some details of molar morphology. The presence of B. mahajambaensis, a rare element in the local rodent fauna, suggests that the region was previously more humid.
Nesomys narindaensis is an extinct rodent that lived in northwestern Madagascar. It is known from subfossil skull bones and isolated molars found in several sites during field work that started in 2001. First described in 2010, it is placed in the genus Nesomys together with three smaller living species, which may differ in some details of molar morphology. The presence of N. narindaensis, a rare element in the local rodent fauna, suggests that the region was previously more humid.
Hipposideros besaoka is an extinct bat from Madagascar in the genus Hipposideros. It is known from numerous jaws and teeth, which were collected in a cave at Anjohibe in 1996 and described as a new species in 2007. The site where H. besaoka was found is at most 10,000 years old; other parts of the cave have yielded H. commersoni, a living species of Hipposideros from Madagascar, and some material that is distinct from both species. H. besaoka was larger than H. commersoni, making it the largest insectivorous bat of Madagascar, and had broader molars and a more robust lower jaw. As usual in Hipposideros, the second upper premolar is small and displaced from the toothrow, and the second lower premolar is large.
Triaenops goodmani is an extinct bat from Madagascar in the genus Triaenops. It is known from three lower jaws collected in a cave at Anjohibe in 1996, and described as a new species in 2007. The material is at most 10,000 years old. A bat humerus from the same site could not be identified as either T. goodmani or the living T. menamena. T. goodmani is identifiable as a member of Triaenops or the related genus Paratriaenops by a number of features of the teeth, such as the single-cusped, canine-like fourth premolar and the presence of a gap between the entoconid and hypoconulid cusps on the first two molars. T. goodmani is larger than the living species of Triaenops and Paratriaenops on Madagascar, and on the first molar the protoconid cusp is only slightly higher than the hypoconid, not much higher as in the other species.
Agathaeromys is an extinct genus of oryzomyine rodents from the Pleistocene of Bonaire, Netherlands Antilles. Two species are known, which differ in size and some details of tooth morphology. The larger A. donovani, the type species, is known from hundreds of teeth that are probably 900,000 to 540,000 years old, found in four localities. A. praeuniversitatis, the smaller species, is known from 35 teeth found in a single fossil site, which is probably 540,000 to 230,000 years old.
Donodontidae is an extinct family of cladotherian mammals known from the Late Jurassic and Early Cretaceous of North Africa. When originally named in 1991, Donodontidae was a monotypic family containing a single species: Donodon perscriptoris. In 2022, four more species were designated and placed within the family: Donodon minor, Stylodens amerrukensis, Anoualestes incidens, and Amazighodon orbis. All five species are endemic to the Ksar Metlili Formation of Morocco, which is dated to the Tithonian and Berriasian. Donodontid fossils are restricted to postcanine teeth and associated jaw fragments.
Dermotherium is a genus of fossil mammals closely related to the living colugos, a small group of gliding mammals from Southeast Asia. Two species are recognized: D. major from the Late Eocene of Thailand, based on a single fragment of the lower jaw, and D. chimaera from the Late Oligocene of Thailand, known from three fragments of the lower jaw and two isolated upper molars. In addition, a single isolated upper molar from the Early Oligocene of Pakistan has been tentatively assigned to D. chimaera. All sites where fossils of Dermotherium have been found were probably forested environments and the fossil species were probably forest dwellers like living colugos, but whether they had the gliding adaptations of the living species is unknown.
Afrasia djijidae is a fossil primate that lived in Myanmar approximately 37 million years ago, during the late middle Eocene. The only species in the genus Afrasia, it was a small primate, estimated to weigh around 100 grams (3.5 oz). Despite the significant geographic distance between them, Afrasia is thought to be closely related to Afrotarsius, an enigmatic fossil found in Libya and Egypt that dates to 38–39 million years ago. If this relationship is correct, it suggests that early simians dispersed from Asia to Africa during the middle Eocene and would add further support to the hypothesis that the first simians evolved in Asia, not Africa. Neither Afrasia nor Afrotarsius, which together form the family Afrotarsiidae, is considered ancestral to living simians, but they are part of a side branch or stem group known as eosimiiforms. Because they did not give rise to the stem simians that are known from the same deposits in Africa, early Asian simians are thought to have dispersed from Asia to Africa more than once prior to the late middle Eocene. Such dispersals from Asia to Africa also were seen around the same time in other mammalian groups, including hystricognathous rodents and anthracotheres.
Indraloris is a fossil primate from the Miocene of India and Pakistan in the family Sivaladapidae. Two species are now recognized: I. himalayensis from Haritalyangar, India and I. kamlialensis from the Pothohar Plateau, Pakistan. Other material from the Potwar Plateau may represent an additional, unnamed species. Body mass estimates range from about 2 kg (4.4 lb) for the smaller I. kamlialensis to over 4 kg (8.8 lb) for the larger I. himalayensis.
Apeomyoides savagei is a fossil rodent from the Miocene of the United States, the only species in the genus Apeomyoides. It is known from fragmentary jaws and isolated teeth from a site in the early Barstovian, around 15–16 million years ago, of Nevada. Together with other species from scattered localities in the United States, Japan, and Europe, Apeomyoides is classified in the subfamily Apeomyinae of the extinct rodent family Eomyidae. Apeomyines are a rare but widespread group that may have been adapted to a relatively dry habitat.
Dentition analyses are systems of tooth and jaw measurement used in orthodontics to understand arch space and predict any malocclusion. Example systems of dentition analysis are listed below.
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