Tupaia miocenica
Encyclopedia
Tupaia miocenica is a fossil
treeshrew
from the Miocene
of Thailand
. Known only from a single tooth, an upper second molar
, it is among the few known fossil treeshrews. With a length of 3.57 mm, the tooth is large for a treeshrew. At the back lingual corner (the side of the tongue), the tooth shows a small cusp
, the hypocone
, that is separated from the protocone
in front of it by a narrow valley. The condition of the hypocone distinguishes this species from various other treeshrews. In addition, the presence of a well-developed but simple mesostyle (a small cuspule) is distinctive.
, a Miocene
site in Thailand. The animal is known from a single tooth, which according to Mein and Ginsburg's comparisons most closely resembles the living treeshrews of the genus Tupaia
. The specific name, miocenica, refers to the animal's occurrence during the Miocene. Only a few other fossil treeshrews are known, and T. miocenica is the only fossil species from Thailand as well as the only Miocene representative of Tupaia.
(M3) known as T Li 175, is large for a treeshrew, with a length of 3.57 mm and width of 4.79 mm. It is dilambdodont (with a W-shaped chewing surface) and the labial surface (the side of the cheeks) is concave and bears a cingular crest. A well-developed small cusp
, a mesostyle, is present on the labial side. The presence of the mesostyle distinguishes the animal from Ptilocercus, the only member of the treeshrew family Ptilocercidae. The lingual (tongue) side is narrow. A large cusp, the protocone
, is on the front lingual corner. Two crests descend from it; one reaches the paracone
on the front labial side and another approaches the metacone
to the back of the tooth. A smaller cusp, a hypocone
, is on the back lingual corner. This feature distinguishes T. miocenica both from the treeshrew genera Dendrogale
, Prodendrogale, and Palaeotupaia, which lack the cusp entirely, and from Anathana and Urogale, which have a large hypocone. In T. miocenica the back and lingual sides of the hypocone are straight and form a right angle with each other. The tooth most closely resembles Tupaia species with a simple mesostyle, such as the common treeshrew
(Tupaia glis). However, this species is smaller and unlike in T. miocenica, the hypocone is not isolated from the protocone by a narrow valley.
, corresponding to the European zone MN 4, around 18 mya. It is in the Thai province of Lamphun
. The fossil fauna encompasses 34 species of mammals, including the tarsier Tarsius thailandicus and the slow loris ? Nycticebus linglom
. Mein and Ginsburg conclude that the fauna represents a tropical forest environment close to a shallow lake.
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
treeshrew
Treeshrew
The treeshrews are small mammals native to the tropical forests of Southeast Asia. They make up the families Tupaiidae, the treeshrews, and Ptilocercidae, the pen-tailed treeshrews, and the entire order Scandentia. There are 20 species in 5 genera...
from the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
of Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. Known only from a single tooth, an upper second molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
, it is among the few known fossil treeshrews. With a length of 3.57 mm, the tooth is large for a treeshrew. At the back lingual corner (the side of the tongue), the tooth shows a small cusp
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
, the hypocone
Hypocone
The hypocone is the name for a main cusp found on the molars of the upper dentition of hominids. It is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an adaptation for the overall grinding and tearing of foods using the occlusal of the tooth...
, that is separated from the protocone
Protocone
thumb|500px|right|Right upper molar showing the four main upper molars cusps.The protocone is a cusp of the molars of the upper dentition in Placental and Marsupial vertebrates .It is found at the mesiolingual area of the tooth...
in front of it by a narrow valley. The condition of the hypocone distinguishes this species from various other treeshrews. In addition, the presence of a well-developed but simple mesostyle (a small cuspule) is distinctive.
Taxonomy
Tupaia miocenica was described in 1997 by French paleontologists Pierre Mein and Léonard Ginsburg in a report on the fossil mammals of Li Mae LongLi Mae Long
Li Mae Long is a fossil site in Lamphun Province, Thailand. The fossils found are thought to date to the late Early Miocene, about 18 million years ago, corresponding to the European zone MN 4.Mammals found at the site include:Marsupials...
, a Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
site in Thailand. The animal is known from a single tooth, which according to Mein and Ginsburg's comparisons most closely resembles the living treeshrews of the genus Tupaia
Tupaia (genus)
Tupaia is a genus of treeshrew in the Tupaiidae family.The genus was first described by Thomas Stamford Raffles in 1821, as having an elongated snout, 8 to 10 incisors, well developed limbs, five-toed naked feet, and the sole furnished with projecting pads and sharp claws, with a habit and tail of...
. The specific name, miocenica, refers to the animal's occurrence during the Miocene. Only a few other fossil treeshrews are known, and T. miocenica is the only fossil species from Thailand as well as the only Miocene representative of Tupaia.
Description
The single known tooth, a worn left second upper molarMolar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
(M3) known as T Li 175, is large for a treeshrew, with a length of 3.57 mm and width of 4.79 mm. It is dilambdodont (with a W-shaped chewing surface) and the labial surface (the side of the cheeks) is concave and bears a cingular crest. A well-developed small cusp
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
, a mesostyle, is present on the labial side. The presence of the mesostyle distinguishes the animal from Ptilocercus, the only member of the treeshrew family Ptilocercidae. The lingual (tongue) side is narrow. A large cusp, the protocone
Protocone
thumb|500px|right|Right upper molar showing the four main upper molars cusps.The protocone is a cusp of the molars of the upper dentition in Placental and Marsupial vertebrates .It is found at the mesiolingual area of the tooth...
, is on the front lingual corner. Two crests descend from it; one reaches the paracone
Paracone
An atmospheric reentry or spaceflight mission abort concept using an inflatable cone.A notable feature of the paracone concept is that it facilitates an abort throughout the entire flight profile....
on the front labial side and another approaches the metacone
Metacone
thumb|500px|left|Right upper molar showing the four main upper molars cusps.The metacone is a cusp on the molars of the upper dentition in hominids. It is found at the buccal distal area of the tooth...
to the back of the tooth. A smaller cusp, a hypocone
Hypocone
The hypocone is the name for a main cusp found on the molars of the upper dentition of hominids. It is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an adaptation for the overall grinding and tearing of foods using the occlusal of the tooth...
, is on the back lingual corner. This feature distinguishes T. miocenica both from the treeshrew genera Dendrogale
Dendrogale
Dendrogale is a genus of treeshrew in the Tupaiidae family. It contains the following species:* Bornean Smooth-tailed Tree Shrew * Northern Smooth-tailed Tree Shrew...
, Prodendrogale, and Palaeotupaia, which lack the cusp entirely, and from Anathana and Urogale, which have a large hypocone. In T. miocenica the back and lingual sides of the hypocone are straight and form a right angle with each other. The tooth most closely resembles Tupaia species with a simple mesostyle, such as the common treeshrew
Common Treeshrew
The Common Treeshrew is a small mammal in the treeshrew family Tupaiidae, and is native to Thailand, Malaysia and Indonesia. It has been listed as Least Concern by IUCN as it remains common and displays some adaptability to ongoing habitat loss.- Description :The common treeshrew is one of the...
(Tupaia glis). However, this species is smaller and unlike in T. miocenica, the hypocone is not isolated from the protocone by a narrow valley.
Range and ecology
Li Mae Long, the collection site of T. miocenica, is dated to the latest Early MioceneEarly Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
, corresponding to the European zone MN 4, around 18 mya. It is in the Thai province of Lamphun
Lamphun Province
Lamphun is one of the northern provinces of Thailand. Neighboring provinces are Chiang Mai, Lampang and Tak.-Geography:Lamphun is located in the river valley of the Ping River, surrounded by mountain chains....
. The fossil fauna encompasses 34 species of mammals, including the tarsier Tarsius thailandicus and the slow loris ? Nycticebus linglom
? Nycticebus linglom
? Nycticebus linglom is a fossil 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...
. Mein and Ginsburg conclude that the fauna represents a tropical forest environment close to a shallow lake.
Literature cited
- Helgen, K.M. 2005. Order Scandentia. Pp. 104–109 in Wilson, D.E. and Reeder, D.M. (eds.). Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp. ISBN 978-0-8018-8221-0
- Mein, P. and Ginsburg, L. 1997. Les mammifères du gisement miocène inférieur de Li Mae Long, Thaïlande : systématique, biostratigraphie et paléoenvironnement. Geodiversitas 19(4):783–844 (in French). Abstract in French and English.
- Sargis, E.J. 2004. New views on tree shrews: The role of Tupaiids in primate supraordinal relationships (subscription required). Evolutionary Anthropology: Issues, News, and Reviews 13(2):56–66.