Exiguodon Temporal range: Miocene Early | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | † Hyaenodonta |
Superfamily: | † Hyainailouroidea |
Family: | † Hyainailouridae |
Subfamily: | † Hyainailourinae |
Tribe: | † Hyainailourini |
Genus: | † Exiguodon Morales & Pickford, 2017 [1] |
Type species | |
†Exiguodon pilgrimi | |
Synonyms | |
synonyms of genus:
synonyms of species:
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Exiguodon ("strict tooth") is an extinct genus of hyainailourid hyaenodont mammal of the subfamily Hyainailourinae. Remains are known from early Miocene deposits in Kenya and Uganda, in East Africa.
Exiguodon is distinguished from other hyainailourines by the following features: diminutive dimensions, lower molars (m3 – m2) with greatly reduced talonid; protoconid and paraconid similar in size. Paraconid of the molars lingually oriented. M2 and M1 close in size and morphology. Occlusal outline sub-triangular, with greatly reduced protocone, which appears like an antero-lingual cingulum which extends anteriorly and buccally. Presence of a strong parastyle in an antero-buccal position, united to the apex of the paracone by a well defined crista. The buccal cingulum borders a wide buccal platform, particularly large in the M2. Paracone tall and narrow, elongated blade-like metastyle. P4 broadened, with reduced protocone and presence of a notch between the main conical cusp and the blade-like posterior cusp. [1]
Exiguodon pilgrimi was originally described as Hyaenodon (Isohyaenodon) pilgrimi by R. J. G. Savage (1965), who coined Isohyaenodon as a subgenus of Hyaenodon . Later authors recognized Isohyaenodon as distinct from Hyaenodon, and Morales and Pickford (2017) eventually realized that pilgrimi was sufficiently distinct from all other African hyainailourines to warrant its own genus, which they named Exiguodon. [1]
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.
Dissopsalis is a genus of teratodontine hyaenodonts of the tribe Dissopsalini. The older species, D. pyroclasticus, lived in Kenya during the middle Miocene, while the type species, D. carnifex, lived in Pakistan and India during the middle to late Miocene.
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.
Many different terms have been proposed for features of the tooth crown in mammals.
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.
Pterodon is an extinct genus of hyaenodont in the family Hyainailouridae, containing five species. The type species Pterodon dasyuroides is known exclusively from the late Eocene to the earliest Oligocene of western Europe. The genus was first erected by the French zoologist Henri Marie Ducrotay de Blainville in 1839, who said that Georges Cuvier presented one of its fossils to a conference in 1828 but died before he could make a formal description of it. It was the second hyaenodont genus with taxonomic validity after Hyaenodon, but this resulted in taxonomic confusion over the validities of the two genera by other taxonomists. Although the taxonomic status of Pterodon was revised during the late 19th and early 20th centuries, it became a wastebasket taxon for other hyaenodont species found in Africa and Asia. Today, only the type species is recognized as belonging to the genus while four others are pending reassessment to other genera.
? Nycticebus linglom is a fossil strepsirrhine primate from the Miocene of Thailand. Known only from a single tooth, an upper third molar, it is thought to be related to the living slow lorises, but the material is not sufficient to assign the species to Nycticebus with certainty, and the species name therefore uses open nomenclature. With a width of 1.82 mm, this tooth is very small for a primate. It is triangular in shape, supported by a single root, and shows three main cusps, in addition to various crests. The absence of a fourth cusp, the hypocone, distinguishes it from various other prosimian primates.
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.
Isohyaenodon is an extinct polyphyletic genus of hyainailourid hyaenodont mammal from the subfamily Hyainailourinae). Remains are known from early to middle Miocene deposits in Kenya, East Africa.
Falcatodon is an extinct genus of hyainailourid hyaenodonts of the subfamily Hyainailourinae, from the Early Oligocene (Rupelian) of the Faiyum Oasis depression in Egypt.
Sectisodon is an extinct genus of hyainailourid hyaenodont mammal of the subfamily Hyainailourinae from early Oligocene to early Miocene deposits in Egypt and Uganda.
Hyainailourinae ("hyena-cats") is an extinct subfamily of hyainailourid hyaenodonts that lived in Africa, Asia, North America and Europe from the middle Eocene to middle Miocene. They appeared in Africa about 47.8 Ma ago and soon after spread as far as East Asia.
Asilifelis is an extinct genus of small felid that lived in what is now Kenya during the Early Miocene. Despite its fragmentary remains, it is remarkable because of its small size and advanced dentition. It contains a single species, Asilifelis cotae.
Katifelis is an extinct genus of felids that lived in what is now Kenya during the Early Miocene and is notable for its dental features, which are intermediate between basal and modern cats. It contains a single species, Katifelis nightingalei.
Diamantofelis is an extinct genus of felids that lived in what is now Namibia during the Early Miocene. It contains a single species, Diamantofelis ferox.
Namafelis is an extinct genus of felids that lived in what is now Namibia during the Early Miocene. It contains a single species, Namafelis minor. Closely related to Diamantofelis, it is of “Pseudaelurus-grade”, and therefore a rather basal member of the cat family.
Myacyon is an extinct genus of large sized carnivoran mammals, belonging to the family Amphicyonidae, that lived in Africa during the Miocene epoch. Due to the limited scope and fragmentary nature of the severely damaged holotype, as well as the illustrations in its descriptions, which have been called inadequate, usage of this genus poses serious issues. However, it is notable for being one of the last surviving members of its family and its adaptions to hypercarnivory. Its relationships to other amphicyonids are obscure, and it is not closely related to Bonisicyon, the other late surviving African genus, although it has been proposed that it descends from a species of Cynelos or Namibiocyon.
Namibiocyon is an extinct genus of carnivoran mammals, belonging to the family Amphicyonidae, that lived in Namibia during the Early Miocene epoch. Before the erection of this taxon in 2022, the type and only species, N. ginsburgi, had been assigned to a variety of other genera. It is notable for its adaptions toward hypercarnivory.