Diatomyidae

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Diatomyidae
Temporal range: 32.5–0  Ma
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Early Oligocene - Recent
Laonastes aenigmamus - young male JP Hugot PLOS ONE.jpg
Young male Laotian rock rat, Laonastes aenigmamus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Suborder: Hystricomorpha
Superfamily: Ctenodactyloidea
Family: Diatomyidae
Mein & Ginsburg, 1997
Type genus
Diatomys
Li, 1974
Genera

Laonastes
Diatomys
Fallomus
Marymus
Willmus
Inopinatia
? Pierremus

Contents

Synonyms

Laonastidae Jenkins et al. 2005

Diatomyidae is a family of hystricomorph rodents. It is represented by a single living species, Laonastes aenigmamus, native to Laos in Southeast Asia. Fossil species are known from the Oligocene and Miocene of Asia and eastern Europe.

"Lazarus effect"

Before Laonastes was discovered, the family Diatomyidae was known only from fossils. The family has a nearly continuous fossil range from Early Oligocene fossils of Fallomus from the Lower Chitarwata Formation (32.5 million years ago, Bugti Member, Bugti Hills, [1] [2] ) in Balochistan, Pakistan, to Middle/Late Miocene fossils (11 Mya) of Diatomys .

Jenkins et al. [3] reported the discovery of a wholly unique new species of rodent, Laonastes aenigmamus, for which they created a new family, Laonastidae. They suggested it was a hystricognath rodent, but basal to all other hystricognaths. Dawson, et al, [4] re-evaluated the phylogenetic position of Laonastes based on morphology and included fossil taxa in their analysis. They determined Laonastes is actually sciurognathous and belongs to the Diatomyidae. They also 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". [5]

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. The enamel on incisors is multiserial (similar to the springhare, gundis, and Hystricognathi). The single premolar on both the upper and lower tooth rows is enlarged (unlike the reduced state in Ctenodactylidae). Most diatomyids have cheek teeth with four roots except for the first. 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.

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, Japan, and Serbia. [6]

Relationship to other rodents

The uniqueness of the Laotian rock rat was clear upon its initial discovery. The results of the phylogenetic analyses [3] were somewhat inconclusive and contradictory. Both morphological and molecular studies suggested Laonastes is a member of the rodent suborder Hystricognathi. The morphological analysis suggested it is the most basal hystricognath. Fossil taxa were not included in the morphological analysis.

Analysis of mtDNA 12S rRNA and cytochrome b sequence, however, suggested Laonastes might be related to living African hystricognaths such as the dassie rat and the naked mole rat. Another type of analysis on the cytochrome b sequence data produced the same result as morphology. Neither analysis, however, showed entirely robust statistical support for the position of Laonastes within the hystricognaths; altogether, it appeared to belong among the basal African radiation.

Dawson et al. [4] also 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 it is closely related to the diatomyids, particularly Diatomys. Their results suggested the Diatomyidae are a sister group to the Ctenodactylidae, and this diatomyid/ctenodactylid clade (along with the Yuomyidae) is sister to the Hystricognathi.

Besides Laonastes, other diatomyids have also been placed in different families. Some [7] [8] placed Diatomys in the family Pedetidae (springhares). Others [9] considered Fallomus to belong to the Chapattimyidae (a completely fossil group). The family Diatomyidae was erected and considered to be a member of the superfamily Ctenodactyloidea. [7] Marivaux et al. [10] united the two into a single family (Diatomyidae), but also suggested this family might be related to the Pedetidae.

Dawson's fossil study [4] was corroborated by more comprehensive DNA sequence analyses, [11] which suggested a roughly Lutetian (about 44 Mya, Early/Middle Eocene) divergence date between the ancestors of the Laotian rock rat and the African gundis, which are each other's closest living relatives. Considering the present-day distribution, the fossil record, and Eocene paleogeography, this divergence probably took place in one of three regions. Either the lineages split in Eurasia, somewhere in today's Zagros Mountains or adjacent ranges of the Alpide belt. These at that time formed a rugged and broken coastline with many offshore islands, as they emerged from the shrinking Tethys Sea. [12] Alternatively, the entire Ctenodactyloidea might be of African origin, or the lineage split took place on India as it joined the Asian mainland, with the gundis reaching Africa via the Mascarene Plateau's archipelagos and island continents. [13] Each hypothesis would unite the paleontological, anatomical, and molecular findings into a robust model. Which one is preferred depends on whether the Hystricomorpha were Laurasian or Gondwanan in origin.

Species

Related Research Articles

<span class="mw-page-title-main">Dasyproctidae</span> Family of rodents

Dasyproctidae is a family of large South American rodents, comprising the agoutis and acouchis. Their fur is a reddish or dark colour above, with a paler underside. They are herbivorous, often feeding on ripe fruit that falls from trees. They live in burrows, and, like squirrels, will bury some of their food for later use.

<span class="mw-page-title-main">Pedetidae</span> Family of rodents

The Pedetidae are a family of rodents. The two living species, the springhares, are distributed throughout much of southern Africa and also around Kenya, Tanzania, and Uganda. Fossils have been found as far north as Turkey. Together with the anomalures and zenkerella, Pedetidae forms the suborder Anomaluromorpha. The fossil genus Parapedetes is also related.

<span class="mw-page-title-main">Aplodontiidae</span> Family of rodents

The family Aplodontiidae also known as Aplodontidae, Haplodontiidae or Haploodontini is traditionally classified as the sole extant family of the suborder Protrogomorpha. It may be the sister family of the Sciuridae. There are fossils from the Oligocene until Miocene in Asia, from Oligocene in Europe and from the Oligocene until the present in North America, where there is the only living species: the mountain beaver.

<span class="mw-page-title-main">Laotian rock rat</span> Species of rodent found in central Laos

The Laotian rock rat or kha-nyou, sometimes called the "rat-squirrel", is a species of rodent found in the Khammouan region of Laos. The species was first described in a 2005 article by Paulina Jenkins and coauthors, who considered the animal to be so distinct from all living rodents, they placed it in a new family, Laonastidae. It is in the monotypic genus Laonastes.

The Chitarwata Formation is a geological formation in western Pakistan, made up of Oligocene and early Miocene terrestrial fluvial facies. The sediments were deposited in coastal depositional environments when Pakistan was partly covered by the Tethys Ocean.

<span class="mw-page-title-main">Gundi</span> Family of rodents

Gundis or comb rats are a group of small, stocky rodents found in Africa. They live in rocky deserts across the northern parts of the continent. The family comprises four living genera and five species, as well as numerous extinct genera and species. They are in the superfamily Ctenodactyloidea. Local people in northern Africa have always known about gundis, however they first came to the notice of western naturalists in Tripoli in 1774, and were given the name gundi mice. While they are not regarded as pests, some people hunt gundis for food.

<span class="mw-page-title-main">Caviomorpha</span> Sub-set of rodents in South America

Caviomorpha is the rodent parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now accepted as a genuine part of the rodents. Caviomorphs include the extinct Heptaxodontidae, the extinct Josephoartigasia monesi and extant families of chinchilla rats, hutias, guinea pigs and the capybara, chinchillas and viscachas, tuco-tucos, agoutis, pacas, pacaranas, spiny rats, New World porcupines, coypu and octodonts.

<span class="mw-page-title-main">Sciurognathi</span> Suborder of rodents

Sciurognathi is a suborder of rodents that includes squirrels, chipmunks, beavers, and many types of mice. The group is characterized by a specific shape to the lower jaw. In sciurognaths, the angular process of the jaw is in the same plane as the root of the incisors. This is in contrast to the suborder Hystricognathi where the angular process is outside the plane formed at the root of the incisor due to the presence of a shelf for muscle attachment.

<span class="mw-page-title-main">Petromuridae</span> Family of rodents

Petromuridae is a family of hystricognath rodents that contains the dassie rat (Petromus typicus) of southwestern Africa, the only extant member of this group.

<span class="mw-page-title-main">Phiomorpha</span> Group of rodents

The rodent parvorder or infraorder Phiomorpha comprises several living and extinct families found wholly or largely in Africa. Along with Anomaluromorpha and perhaps the extinct Zegdoumyidae, it represents one of the few early colonizations of Africa by rodents.

<span class="mw-page-title-main">Hystricomorpha</span> Suborder of rodents

Hystricomorpha is a term referring to families and orders of rodents which has had many definitions throughout its history. In the broadest sense, it refers to any rodent with a hystricomorphous zygomasseteric system. This includes the Hystricognathi, Ctenodactylidae, Anomaluridae, and Pedetidae. Molecular and morphological results suggest the inclusion of the Anomaluridae and Pedetidae in Hystricomorpha may be suspect. Based on Carleton & Musser 2005, these two families are discussed here as representing a distinct suborder Anomaluromorpha.

<span class="mw-page-title-main">Anomaluromorpha</span> Suborder of rodents

Anomaluromorpha is a clade that unites the anomalures, springhares, and zenkerella. It has alternately been designated as either a suborder or infraorder. Most recently, Carleton & Musser 2005 recognized it as one of five suborders of rodents.

<i>Diatomys</i> Extinct genus of rodents

Diatomys is an extinct rodent genus known from Miocene deposits in China, Japan, Pakistan, and Thailand. The fossil range is from the late Early Miocene to the Middle Miocene.

<span class="mw-page-title-main">Mary R. Dawson</span> American paleontologist (1931–2020)

Mary R. Dawson was a vertebrate paleontologist and curator emeritus at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.

<span class="mw-page-title-main">Cameroon scaly-tail</span> Species of rodent

The Cameroon scaly-tail, also referred to as the Cameroon anomalure, flightless anomalure or flightless scaly-tail, is a rodent species endemic to West Central Africa. The scientific literature has never reported observations of live individuals. The taxonomic classification of the species has been subject to recent revision.

Gobiomyidae is a small extinct family of rodents from the Eocene of Asia. The family contains four genera and belongs to the superfamily Ctenodactyloidea, which also contains the living Laotian rock rat and gundis and their fossil relatives. When Wang named the family, gobiomyids were considered the closest known relatives of Ctenodactylidae, but newer research indicates that Diatomyidae is more closely related to living ctenodactylids.

<span class="mw-page-title-main">Ctenodactylomorphi</span> Infraorder of rodents

Ctenodactylomorphi is an infraorder of the rodent suborder Hystricomorpha that includes two living families, the Ctenodactylidae (gundis) and the Diatomyidae.

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.

This paleomammalogy list records new fossil mammal taxa that were described during the year 2012, as well as notes other significant paleomammalogy discoveries and events which occurred during that year.

References

  1. 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.
  2. 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.
  3. 1 2 Jenkins, Paulina D.; Kilpatrick, C. William; Robinson, Mark F. & Timmins, Robert J. (2004): Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity2(4): 419-454. doi : 10.1017/S1477200004001549 (HTML abstract). Erratum: Systematics and Biodiversity3(3):343. doi : 10.1017/S1477200005001775
  4. 1 2 3 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.
  5. "Back from the dead: Living fossil identified". NBC News . 9 March 2006.
  6. Marković, Zoran; Wessels, Wilma; van de Weerd, Andrew A.; de Bruijn, Hans (2018-09-01). "On a new diatomyid (Rodentia, Mammalia) from the Paleogene of south-east Serbia, the first record of the family in Europe". Palaeobiodiversity and Palaeoenvironments. 98 (3): 459–469. doi:10.1007/s12549-017-0301-4. ISSN   1867-1608. PMC   6417379 . PMID   30956714.
  7. 1 2 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.
  8. 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
  9. 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, [ permanent dead link ]
  10. 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.
  11. Huchon, Dorothée; Chevret, Pascale; Jordan, Ursula; Kilpatrick, C. William; Ranwez, Vincent; Jenkins, Paulina D.; Brosius, Jürgen & Schmitz, Jürgen (2007): Multiple molecular evidences for a living mammalian fossil. PNAS 104(18): 7495-7499. doi : 10.1073/pnas.0701289104 (HTML abstract)
  12. 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.
  13. 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.
  14. López-Antoñanzas, R. (2010). "First diatomyid rodent from the Early Miocene of Arabia" (PDF). Naturwissenschaften. 98 (2): 117–123. doi:10.1007/s00114-010-0745-0. PMID   21136247. S2CID   41698521.