? Diatomyidae Fossil range: Early Oligocene - Recent
Illustration submitted by the journal Science
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia Suborder: Hystricomorpha Family: Diatomyidae Mein & Ginsburg, 1997
Genera
Laonastes †Diatomys †Fallomus †Willmus

Diatomyidae is a family of hystricomorphous, sciurognathous rodents found in Asia. It is currently represented by a single living species, Laonastes aenigmamus. The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ... Image File history File links Ratsquriiall. ... Science is the journal of the American Association for the Advancement of Science (AAAS). ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Typical Classes Subphylum Urochordata - Tunicates Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... Families Many, see text The order Rodentia is the most numerous of all the branches on the mammal family tree. ... Families Ctenodactylidae †Tammquammyidae †Diatomyidae †Yuomyidae †Chapattimyidae †Tsaganomyidae Laonastidae †Baluchimyinae Hystricidae †Myophiomyidae †Diamantomyidae †Phiomyidae †Kenyamyidae Petromuridae Thryonomyidae Bathyergidae †Bathyergoididae Erethizontidae Dasyproctidae Agoutidae †Eocardiidae Dinomyidae Caviidae Hydrochaeridae Octodontidae Ctenomyidae Echimyidae Myocastoridae Capromyidae †Heptaxodontidae Chinchillidae †Neoepiblemidae Abrocomidae Skull of a capybara showing the enlarged infraorbital canal present in most members of the Hystricomorpha. ... Binomial name Laonastes aenigmamus (Jenkins, Kilpatrick, Robinson, Timmins, 2005) The kha-nyou or Laotian Rock Rat (Laonastes aenigmamus) is a rodent from the Khammouan region of Laos. ... Species Diatomys shantungensis Li, 1974 Diatomys liensis Mein & Ginsburg, 1985 Diatomys is a hystricomorphous sciurognathous rodent known from Miocene deposits in China, Japan, Pakistan, and Thailand. ... A type of rodent zygomasseteric system where the infraorbital foramen, which runs from the anterior part of the orbit to the outside of the rostrum, becomes very large. ... Families See Classification Section The order Rodentia is the most numerous of all the branches on the mammal family tree. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Binomial name Laonastes aenigmamus (Jenkins, Kilpatrick, Robinson, Timmins, 2005) The kha-nyou or Laotian Rock Rat (Laonastes aenigmamus) is a rodent from the Khammouan region of Laos. ...

"Lazarus effect"

Prior to the discovery of Laonastes, the family Diatomyidae was known only from fossils. The family has a nearly continuous fossil range from Early Oligocene fossils of Fallomus from Lower Chitarwata Formation (32.5 Ma; Bugti Member, Bugti Hills; Flynn et al., 1986) in Balochistan, Pakistan to Middle/Late Miocene fossils (11 Ma) of Diatomys. In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears from one or more periods of the fossil record, only to appear again later. ... A fossil Ammonite Fossils (from Latin fossus, literally having been dug up) are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. ... The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ... Annum is a Latin term meaning year. ... View of the Bugti Hills. ... The neutrality of this article is disputed. ... The Miocene epoch is a period of time that extends from about 23 to 5. ... Species Diatomys shantungensis Li, 1974 Diatomys liensis Mein & Ginsburg, 1985 Diatomys is a hystricomorphous sciurognathous rodent known from Miocene deposits in China, Japan, Pakistan, and Thailand. ...

Jenkins et al. (2004) reported the discovery of a wholly unique new species of rodent, Laonastes aenigmamus, for which they created a new family, Laonastidae. They suggested that it was a hystricognath rodent, but basal to all other hystricognaths. Dawson et al. (2006) re-evaluated the phylogenetic position of Laonastes based on morphology and included fossil taxa in their analysis. They determined that Laonastes is actually sciurognathous and that it belongs to the Diatomyidae. Hystricognathi is a subordo of the Rodentia. ... In phylogenetics, basal members of a group are subgroups that diverged very early from the others. ... A phylogenetic tree is a tree showing the evolutionary interrelationships among various species or other entities that are believed to have a common ancestor. ... Morphology is the following: In linguistics, morphology is the study of the structure of word forms. ...

Dawson et al. (2006) described the Diatomyidae as a Lazarus taxon due to the 11 million year gap between the most recent diatomyid in the fossil record and the existence of Laonastes today. The only other comparable length of time for a mammal Lazarus taxon is the Monito del Monte, which is part of a family (Microbiotheriidae) also most recently known from Miocene deposits. Mary Dawson described Laonastes as the "coelacanth of rodents" [1]. In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears from one or more periods of the fossil record, only to appear again later. ... Binomial name Dromiciops gliroides Thomas, 1894 Synonyms Dromiciops australis The Monito del Monte (little mountain monkey, Dromiciops gliroides) is a semi-arboreal South American marsupial which is thought to be more closely related to the marsupials of Australasia than to those of the Americas. ... Binomial name Dromiciops australis Thomas, 1894 The Monito del Monte (little mountain monkey, Dromiciops australis) is a semi-arboreal South American marsupial which is thought to be more closely related to the marsupials of Australasia than to those of the Americas. ... Species Latimeria chalumnae Latimeria menadoensis Coelacanth (meaning hollow thorn, from the greek coelia, κοιλιά (hollow) and acanthos, άκανθος (thorn)); IPA: ) is a species of fish and represents the oldest lineage of living fish known to date. ...

Characteristics

The Diatomyidae are similar to both the Ctenodactylidae and the Anomaluromorpha in being simultaneously hystricomorphous and sciurognathous. The masseteric fossa in diatomyids is enlarged and extends to below the first cheek tooth (p4). The enamel on incisors is multiserial (similar to the Pedetidae, Ctenodactylidae, and Hystricognathi). The single premolar on both the upper and lower toothrows is enlarged (unlike the reduced state in Ctenodactylidae). Most diatomyids have cheek teeth with four roots except for p4. In Laonastes, the lower molars have four roots, but upper cheek teeth have three roots including a U-shaped anterior root that may be derived from the merging of two roots. Genera Ctenodactylus Felovia Massoutiera Pectinator Gundis (family Ctenodactylidae) are a group of small, stocky rodents found in Africa. ... Families Anomaluridae †Parapedetidae Pedetidae Anomaluromorpha is the name given to a clade that unites the anomalures with the springhare. ... The word enamel can mean more than one thing: Tooth enamel Vitreous enamel Enamel (markup language) Enameled wire This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Incisors are the first kind of tooth in heterodont mammals. ... ... Genera Ctenodactylus Felovia Massoutiera Pectinator Gundis (family Ctenodactylidae) are a group of small, stocky rodents found in Africa. ... Hystricognathi is a subordo of the Rodentia. ... The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. ...

Living diatomyids are only represented by the Laotian Rock Rat from the Khammouan region of Laos. Fossil diatomyids have been recovered in Pakistan, India, Thailand, China, and Japan. Khammouan (Lao ຄໍາມ່ວນ) is a province of Laos, located in the south of the country. ...

Relationship to other rodents

The uniqueness of the Laotian Rock Rat was clear upon its initial discovery. The results of the phylogenetic analyses performed by Jenkins et al. (2004) were somewhat inconclusive and contradictory. Both morphological and molecular studies suggested Laonastes is a member of the rodent suborder Hystricognathi. The morphological analysis suggested that it is the most basal hystricognath. Binomial name Laonastes aenigmamus (Jenkins, Kilpatrick, Robinson, Timmins, 2005) The Kha-nyou or Laotian Rock Rat (Laonastes aenigmamus), popularly denoted Rat-squirrel, is a rodent from the Khammouan region of Laos. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Comparative anatomy is the study of similarities and differences in organisms. ... Molecular systematics is a product of the traditional field of systematics and the growing field of bioinformatics. ... Hystricognathi is a subordo of the Rodentia. ... In phylogenetics, basal members of a group are subgroups that diverged very early from the others. ...

The molecular analyses, however, suggested that Laonastes is related to the living African hystricognaths such as the dassie rats and the Naked Mole Rat. Another type of analysis on the same data produces the same result as morphology; Laonestes represents the earliest split among hystricognaths. Neither analysis, however, shows more than moderate statistical support for the relationship of Laonastes within the hystricognaths. Jenkins et al. (2004) did not include any fossil taxa in their analyses. Binomial name Petromus typicus A. Smith, 1831 The Dassie Rat, Petromus typicus, is an African rodent found among rocky outcroppings. ... Binomial name Heterocephalus glaber Rüppell, 1842 The Naked Mole Rat (Heterocephalus glaber), also known as the Sand Puppy, or desert mole rat, is a very unusual burrowing rodent native to parts of East Africa, predominately South Ethiopia, Kenya, and Somalia. ...

Dawson et al. (2006) refuted the notion that Laonastes is a hystricognath and instead argued that the mandible is sciurognathous. They evaluated Laonastes in comparison to several fossil rodents and determined that it is closely related to the diatomyids, particularly Diatomys. Their results suggested that the Diatomyidae are a sister group to the gundis, Ctenodactylidae, and that this diatomyid/ctenodactylid clade (along with the Youmyidae) is sister to the Hystricognathi. The mandible (inferior maxillary bone) (together with the maxilla) is the largest and strongest bone of the face. ...

Besides Laonastes, other diatomyids have also been placed in different families. Mein and Ginsburg (1986) and McKenna and Bell (1997) placed Diatomys in the Pedetidae (the springhare family). Flynn et al. (1986) considered Fallomus to belong to the Chapattimyidae (a completely fossil group). Mein and Ginsburg (1997) erected the family Diatomyidae and considered it to be a member of the superfamily Ctenodactyloidea. Marivaux et al. (2004) united the two into a single family (Diatomyidae), but also suggested that this family might be related to the Pedetidae.

Species

• †Fallomus
  • †Fallomus razae
  • †Fallomus ladakhensis
  • †Fallomus ginsburgi
  • †Fallomus quraishyi
• †Diatomys
  • †Diatomys shantungensis
  • †Diatomys liensis
• †Willmus
  • †Willmus maximus
• Laonastes
  • Laonastes aenigmamus - Laotian Rock Rat

Species Diatomys shantungensis Li, 1974 Diatomys liensis Mein & Ginsburg, 1985 Diatomys is a hystricomorphous sciurognathous rodent known from Miocene deposits in China, Japan, Pakistan, and Thailand. ... Species Diatomys shantungensis Li, 1974 Diatomys liensis Mein & Ginsburg, 1985 Diatomys is a hystricomorphous sciurognathous rodent known from Miocene deposits in China, Japan, Pakistan, and Thailand. ... Species Diatomys shantungensis Li, 1974 Diatomys liensis Mein & Ginsburg, 1985 Diatomys is a hystricomorphous sciurognathous rodent known from Miocene deposits in China, Japan, Pakistan, and Thailand. ... Binomial name Laonastes aenigmamus (Jenkins, Kilpatrick, Robinson, Timmins, 2005) The kha-nyou or Laotian Rock Rat (Laonastes aenigmamus) is a rodent from the Khammouan region of Laos. ... Binomial name Laonastes aenigmamus (Jenkins, Kilpatrick, Robinson, Timmins, 2005) The kha-nyou or Laotian Rock Rat (Laonastes aenigmamus) is a rodent from the Khammouan region of Laos. ...

References

• Dawson, M. R., L. Marivaux, C.-k. Li, K. C. Beard, and G. Métais. 2006. Laonastes and the "Lazarus effect" in Recent mammals. Science, 311:1456-1458.
• Flynn, L. J., L. L. Jacobs, and I. U. Cheema. 1986. Baluchimyinae, a new ctenodactyloid subfamily from the Miocene of Baluchistan. American Museum Novitates, 2841:1-58.
• Flynn, L. J. and M. E. Morgan. 2005. An Unusual Diatomyid Rodent from an Infrequently Sampled Late Miocene Interval in the Siwaliks of Pakistan, Palaeontologia Electronica Vol. 8, Issue 1; 17A:10p, [2]
• Jenkins, P. D., C. W. Kilpatrick, M. F. Robinson, and R. J. Timmins. 2004. Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity, 2:419-454.
• Marivaux, L., M. Vianey-Liaud, and J.-J. Jaeger. 2004. High-level phylogeny of early Tertiary rodents: dental evidence. Zoological Journal of the Linnean Society, 142:105-134.
• Marivaux, L. & Welcomme, J.-L. 2003. New diatomyid and baluchimyine rodents from the Oligocene of Pakistan (Bugti Hills, Balochistan): Systematic and paleobiogeographic implications. Journal of Vertebrate Paleontology 23:420-434.
• Marivaux, L. J. L. Welcomme, M. Vianey-Liaud, and J.J. Jaeger. 2002. The role of Asia in the origin and diversification of hystricognathous rodents. Zoologica Scripta, 31:225-239.
• McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp. ISBN 0-231-11013-8
• Mein, P. and L. Ginsburg, L. 1985. Les rongeurs miocènes de Li (Thailande). Compte Rendus de l’Académie des Sciences, Paris, Série II, 301:1369-1374.
• Mein, P. and L. Ginsburg. 1997. - Les mammifères du gisement miocène inférieur de Li Mae Long, Thaïlande : systématique, biostratigraphie et paléoenvironnement. Geodiversitas 19 (4) : 783-844.
• Nanda, A.C. & Sahni, A. 1998. Ctenodactyloid rodent assemblage from Kargil Formation, Ladakh molasses group: Age and paleobiogeographic implications for the Indian subcontinent in the Oligo-Miocene. Geobios 31:533-544.

External links

• Carnegie Museum Press Release: "New family of mammal really living fossil" with images
• Detailed article on finding that Laonastes is a diatomyid
• Another article on finding that Laonastes is a diatomyid