Laotian rock rat Laonastes aenigmanus, a relictual member of the Hystricomorpha from south-east Asia. Photo from here.

Belongs within: Rodentia.
Contains: Hystricognathiformes.

The name Hystricomorpha has been used for a supposed clade of rodents characterised by a large infraorbital foramen, allowing for the passage of the M. masseter medialis, as well as a tendency to develop a complete hypolophid and anterior displacement of the entoconid on the lower molars (Jaeger 1988). However, it is uncertain whether rodents showing this feature form a monophyletic clade, and it has possibly evolved more than once. Early myomorphs, in particular, had a hystricomorph-like infraorbital foramen (Jaeger 1988). The molecular analysis of mammals by Meredith et al. (2011) supports a clade of Ctenodactylidae, Diatomyidae and Hystricognathi, but places the ‘hystricomorph’ Anomaluromorpha elsewhere among the rodents.

The Diatomyidae are a family of rodents originally described as fossils from the early Oligocene to late Miocene. However, the Laotian rock rat Laonastes aenigmanus, only described in 2005, has subsequently been identified as a living member of the Diatomyidae (Naish 2010).

<==Hystricomorpha [Ctenohystrica, Entodacrya, Hystricognatha]
    |  |  `--ProtataromysMJ11
    |  `--+--CtenodactylidaeMJ11
    |     |    |  i. s.: Africanomys pulcherL78
    |     |    |         Metasayimys jebeliL78
    |     |    |         Woodomys Shevyreva 1971SM93
    |     |    |         Karakoromys Matthew & Granger 1923SM93
    |     |    |--Felovia vaeFS15
    |     |    `--+--Massouriera mzabiFS15
    |     |       `--+--Pectinator spekeiFS15
    |     |          `--CtenodactylusFS15
    |     |               |--C. gundiN05
    |     |               `--C. valiN05
    |     `--DiatomyidaeMJ11
    |          |  i. s.: WillmusDM06
    |          |--Fallomus Flynn et al. 1989DM06, SM93
    |          `--+--Diatomys shantungensisDM06
    |             `--Laonastes Jenkins, Kilpatrick et al. 2005DM06, JK05 [Laonastidae]
    |                  `--*L. aenigmamus Jenkins, Kilpatrick et al. 2005JK05
       |    |--Birbalomys Sahni & Khare 1973SM93
       |    |--Shkhikvadzomys Shevyreva 1989SM93
       |    |--Bolosomys Shevyreva 1989SM93
       |    |--Esasempomys Shevyreva 1989SM93
       |    `--Chapattimys Hussain 1978SS09, SM93
       |         `--C. wilsoniSS09
       `--+--+--Anadianomys declivisSS09
          |  `--HystricognathiformesMJ11
               |--Yuomys cavioidesSS09
               |--Dianomys Wang 1984SM93
               |--Advenimus Dawson 1964SM93
               |    `--A. hupeiensis Dawson et al. 1984MHL03
               `--Petrokozlovia Shevyreva 1972SM93
                    `--P. notosSS09
Hystricomorpha incertae sedis:
    |--Neoepiblema Ameghino 1889SM93
    |--Phoberomys Kraglievich 1926 [incl. Dabbenea]SM93
    |    `--P. pattersoniD07
    `--Perimys Ameghino 1887SM93
         |--P. erutusS32
         |--P. impactusS32
         |--P. incavatus Ameghino 1902S32
         |--P. onustusS32
         |--P. puellusS32
         `--P. transversusSA32

*Type species of generic name indicated


[DM06] Dawson, M. R., L. Marivaux, C.-K. Li, K. C. Beard & G. Métais. 2006. Laonastes and the “Lazarus effect” in recent mammals. Science 311: 1456–1458.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[FS15] Faurby, S., & J.-C. Svenning. 2015. A species-level phylogeny of all extant and late Quaternary extinct mammals using a novel heuristic-hierarchical Bayesian approach. Molecular Phylogenetics and Evolution 84: 14–26.

[JK05] Jenkins, P. D., C. W. Kilpatrick, M. F. Robinson & R. J. Timmins. 2005. Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity 2 (4): 419–454.

[L78] Lavocat, L. 1978. Rodentia and Lagomorpha. In: Maglio, V. J., & H. B. S. Cooke (eds) Evolution of African Mammals pp. 69–89. Harvard University Press: Cambridge (Massachusetts).

[MHL03] Meng, J., Y. Hu & C. Li. 2003. The osteology of Rhombomylus (Mammalia, Glires): implications for phylogeny and evolution of Glires. Bulletin of the American Museum of Natural History 275: 1–247.

[MJ11] Meredith, R. W., J. E. Janečka, J. Gatesy, O. A. Ryder, C. A. Fisher, E. C. Teeling, A. Goodbla, E. Eizirik, T. L. L. Simão, T. Stadler, D. L. Rabosky, R. L. Honeycutt, J. J. Flynn, C. M. Ingram, C. Steiner, T. L. Williams, T. J. Robinson, A. Burk-Herrick, M. Westerman, N. A. Ayoub, M. S. Springer & W. J. Murphy. 2011. Impacts of the Cretaceous terrestrial revolution and KPg extinction on mammal diversification. Science 334: 521–524.

Nutt, K. J. 2005. Philopatry of both sexes leads to the formation of multimale, multifemale groups in Ctenodactylus gundi (Rodentia: Ctenodactylidae). Journal of Mammalogy 86 (5): 961–968.

[SS09] Sallam, H. M., E. R. Seiffert, M. E. Steiper & E. L. Simons. 2009. Fossil and molecular evidence constrain scenarios for the early evolutionary and biogeographic history of hystricognathous rodents. Proceedings of the National Academy of Sciences of the USA 106 (39): 16722–16727.

[S32] Simpson, G. G. 1932. Some new or little-known mammals from the Colpodon beds of Patagonia. American Museum Novitates 575: 1–12.

[SM93] Stucky, R. K., & M. C. McKenna. 1993. Mammalia. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 739–771. Chapman & Hall: London.

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