Belongs within: Hystricomorpha.
Contains: Hystricognathi.
The Hystricognathiformes are a group of rodents including the living Hystricognathi and fossil relatives, with an angular process on the mandible lateral to the incisor alveolus (Meng et al. 2003). Fossil taxa that have been allied with the hystricognaths include the squirrel-like Cylindrodontidae. Cylindrodontids were most diverse in the Eocene of North America, with a small number of species known from the late Eocene or early Oligocene of Asia (Emry & Korth 1996). Separate subfamilies have been recognised for the Cylindrodontinae, with four distinct transverse lophs on the cheek teeth, and Jaywilsonomys, with only three lophs and shorter upper cheek teeth. Other potential hystricognathiforms include the Tsaganomyidae from the Oligocene of Asia. Tsaganomyids had long procumbent incisors like those of modern mole-rats, and like them may have used its incisors for digging (Meng et al. 2003).
The Baluchimyinae are from the Palaeogene of Asia have been found by phylogenetic analysis to be paraphyletic to crown hystricognaths (Sallam et al. 2009). Baluchimyines are characterised by relatively high-crowned, markedly lophodont teeth. The Asian baluchimyines gave rise to an African clade including Protophiomys, Waslamys and the Myophiomyidae that was itself more directly ancestral to the hystricognaths. The Myophiomyidae were small species from the Oligocene and lower Miocene, bearing cricetodontoid cheek teeth with prominent cusps and lower crests (Lavocat 1978).
Synapomorphies (from Meng et al. 2003): P4 with strong anterior and posterior ridges lacking a cusp; precingulum confluent with protocone to form a strong loph; entoconid of lower molar posteriorly shifted. Mandible with angular process originating lateral to incisor alveolus; nasolacrimal duct medial to incisor. Orbital wing absent from palatine; orbital process of alisphenoid greatly reducted; alisphenoid contacting frontal.
<==HystricognathiformesMHL03
|--BaluchimyinaeSS09
| |--Baluchimys Flynn et al. 1989SS09, SM93
| | |--B. krabienseSS09
| | `--+--B. ganeshapherSS09
| | `--Lindsaya Flynn et al. 1989 non Lindsaea Dryand. 1793 [ICBN]SS09, SM93
| | `--L. derabugtiensisSS09
| `--+--+--Sacaresia moyaeponsiSS09
| | `--+--Ottomania proavitaSS09
| | `--Confiniummys sidikiSS09
| `--+--+--Lophibaluchia Flynn et al. 1989SS09, SM93
| | `--+--Hodsahibia Flynn et al. 1989SS09, SM93
| | `--Bugtimys zafarullahiSS09
| `--+--Protophiomys Jaeger et al. 1985SS09
| | |--*P. algeriensis Jaeger et al. 1985SS09
| | `--P. aegyptensis Sallam, Seiffert et al. 2009SS09
| |--+--HystricognathiSS09
| | `--Waslamys Sallam, Seiffert et al. 2009SS09
| | `--*W. attiai Sallam, Seiffert et al. 2009SS09
| `--+--‘Phiomys’ lavocati Wood 1968SS09, W68
| `--MyophiomyidaeL78
| |--Elmerimys woodiL78
| |--Phiomyoides humilisL78
| |--Myophiomys Lavocat 1973SM93
| | `--M. arambourgiL78
| `--Phiocricetomys Wood 1968SS09, W68
| `--*P. minutus Wood 1968W68
`--+--Tsaganomyidae [Tsaganomyinae]SM93
| |--Beatomus Shevyreva 1972SM93
| |--Sepulkomys Shevyreva 1972SM93
| `--Tsaganomys Matthew & Granger 1923MHL03, SM93 [incl. Morosomys Shevyreva 1972EK96, SM93]
| |--T. altaicusMHL03
| `--‘Morosomys’ silentiumis Shrevyreva 1972EK96
`--CylindrodontidaeSM93
| i. s.: Downsimys Flynne et al. 1986SM93
| TuscahomysB08
| PareumysW96
| |--P. grangeri Burke 1935W96
| |--P. guensbergiP96
| |--P. milleriP96
| `--P. troxelliP96
| Anomoemys Wang 1986EK96
| MysopsR06
| |--M. kalicolaG52
| `--M. parvusMFT96
| ProardynomysR06
|--Jaywilsonomys Ferrusquia & Wood 1969 [Jaywilsonomyinae]EK96
| |--*J. ojinagaensis Ferrusquia & Wood 1969EK96
| `--J. pintoensis Ferrusquia & Wood 1969EK96
`--CylindrodontinaeEK96
|--Dawsonomys Gazin 1961SM93
| `--D. woodiEK96
|--Ardynomys Matthew & Granger 1925EK96
| |--A. occidentalis Burke 1936EK96
| |--A. olseniEK96
| |--A. russelliCND05
| `--A. saskatchewaensis (Lambe 1908) [=Sciurus saskatchewaensis, Prosciurus saskatchewaensis]EK96
|--Cylindrodon Douglass 1902EK96
| |--*C. fontis Douglass 1902EK96
| |--C. collinus Russell 1972 [incl. Prosciurus altidens Russell 1972, Plesispermophilus altidens]EK96
| |--C. natronensis Emry & Korth 1996EK096
| |--C. nebraskensis Hough & Alf 1956EK96
| `--C. solarborus Emry & Korth 1996EK96
`--Pseudocylindrodon Burke 1935EK96
|--*P. neglectus Burke 1935 [incl. P. sylvaticus Russell 1954]EK96
|--P. citofluminisS96
|--P. lateriviaeS96
|--P. medius Burke 1938EK96
`--P. texanus Wood 1974EK96
*Type species of generic name indicated
References
[B08] Beard, K. C. 2008. The oldest North American primate and mammalian biogeography during the Paleocene–Eocene Thermal Maximum. Proceedings of the National Academy of Sciences of the USA 105 (10): 3815–3818.
[CND05] Clarke, J. A., M. A. Norell & D. Dashzeveg. 2005. New avian remains from the Eocene of Mongolia and the phylogenetic position of the Eogruidae (Aves, Gruoidea). American Museum Novitates 3494: 1–17.
[EK96] Emry, R. J., & W. W. Korth. 1996. Cylindrodontidae. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 399–416. Cambridge University Press.
[G52] Gazin, C. L. 1952. The Lower Eocene Knight Formation of western Wyoming and its mammalian faunas. Smithsonian Miscellaneous Collections 117 (18): 1–82, 11 pls.
[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).
[MFT96] McCarroll, S. M., J. J. Flynn & W. D. Turnbull. 1996. Biostratigraphy and magnetostratigraphy of the Bridgerian-Uintan Washakie Formation, Washakie Basin, Wyoming. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 25–39. Cambridge University Press.
[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.
[P96] Prothero, D. R. 1996. Magnetic stratigraphy and biostratigraphy of the Middle Eocene Uinta Formation, Uinta Basin, Utah. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 3–24. Cambridge University Press.
[R06] Rose, K. D. 2006. The Beginning of the Age of Mammals. John Hopkins University Press: Baltimore.
[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.
[S96] Storer, J. E. 1996. Eocene-Oligocene faunas of the Cypress Hills Formation, Saskatchewan. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 240–261. Cambridge University Press.
[SM93] Stucky, R. K., & M. C. McKenna. 1993. Mammalia. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 739–771. Chapman & Hall: London.
[W96] Walsh, S. L. 1996. S. Middle Eocene mammal faunas of San Diego County, California. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 75–119. Cambridge University Press.
[W68] Wood, A. E. 1968. The African Oligocene Rodentia. Peabody Museum of Natural History, Yale University, Bulletin 28: 23–105.