Eutherapsida

Reconstruction of Ulemosaurus svijagensis, copyright Dmitry Bogdanov.

Belongs within: Therapsida.
Contains: Dicynodontia, Cynodontia.

The Eutherapsida are the clade of synapsids uniting modern mammals with the Permian Dinocephalia. Members of the clade are characterised by a bowing of the zygomatic arch and increase in size of the temporal fenestra, together with loss of the olecranon ulnae and reduction of the fifth pedal digit to three phalanges.

<==Eutherapsida [Anomodontia, Cryptodontia] S03
    |  i. s.: Theriognathus Broom 1920 C07, D07
    |           `--T. microps D07
    |         Endothiodon [Endothiodontia] C07
    |         Dromasauria R61
    |           |--Galeops R61
    |           |--Galechirus R61
    |           `--Galepus R61
    |--+--Dicynodontia S03
    |  `--Theriodontia [Therosauria] S03
    |       |  i. s.: Binaralia C07
    |       |           |--Lycosaurus C07
    |       |           `--Tigrisuchus C07
    |       |         Inostrancevia [Inostranceviidae] C07
    |       |           |--I. annae C07
    |       |           `--I. uralensis Tatarinov 1974 TT05
    |       |         Ericiolacerta Watson 1931 [Ericiolacertidae] D07
    |       |           `--E. parva D07
    |       |--Gorgonops C07 [Gennetotheria, Gorgonopsia S03, Tectinaralia]
    |       `--Eutheriodontia HK01
    |            |--Cynodontia S03
    |            `--Therocephalia S03
    |                 |  i. s.: Lycosuchus HK01
    |                 |         Promoschorhynchus S03
    |                 |--Bauria HK01 [Bauriamorpha, Baurioidea K88]
    |                 `--Whaitsiidae K88
    `--Dinocephalia S03
         |  i. s.: Rhopalodon TT05
         |         Sinophoneus Cheng & Ji 1996 CL97
         |         Microsyodon orlovi CL97
         |         Estemmenosuchus Tchudinov 1960 D07 [Estemmenosuchidae TT05]
         |           |--E. mirabilis D07
         |           `--E. uralensis D07
         |--Stenocybus Cheng & Li 1997 [Stenocybusidae] CL97
         |    `--*S. acidentatus Cheng & Li 1997 CL97
         `--+--Tapinocephalidae [Tapinocephalia, Tretospondylia] CL97
            |    |--Tapinocephalus C07
            |    `--Ulemosaurus Rjabinin 1938 TT05, D07
            |         |--U. gigas TT05
            |         `--U. svijagensis D07
            `--Anteosauridae [Anteosauria] CL97
                 |--Titanophoneus adamanteus (Orlov 1958) CL97, TT05
                 |--Deuterosaurus jubilaei (von Nopcsa 1928) TT05
                 |--Syodon CL97
                 |--Australosyodon CL97
                 `--Anteosaurus Watson 1921 D07
                      `--A. magnificus D07

*Type species of generic name indicated

REFERENCES

[C07] Case, E. C. 1907. Revision of the Pelycosauria of North America. Carnegie Institute of Washington Publication 55: 1–176, 35 pls.

[CL97] Cheng Z. & Li J. 1997. A new genus of primitive dinocephalian—the third report on Late Permian Dashankou lower tetrapod fauna. Vertebrata PalAsiatica 35 (1): 35–43.

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

[HK01] Hopson, J. A., & J. W. Kitching. 2001. A probainognathian cynodont from South Africa and the phylogeny of nonmammalian cynodonts. Bulletin of the Museum of Comparative Zoology 156 (1): 5–35.

[K88] Kemp, T. S. 1988. Interrelationships of the Synapsida. In: Benton, M. J. (ed.) The Phylogeny and Classification of the Tetrapods vol. 2. Mammals pp. 1–22. Clarendon Press: Oxford.

[R61] Romer, A. S. 1961. Synapsid evolution and dentition. In: Vandebroek, G. (ed.) International Colloquium on the Evolution of Lower and Non Specialized Mammals. Koninklijke Vlaames Academie voor Wetenschappen, Letteren en Schone Kunsten van Belgie—Klasse der Wetenschapen 1961 (1): 9–56.

[S03] Sidor, C. A. 2003. The naris and palate of Lycaenodon longiceps (Therapsida: Biarmosuchia), with comments on their early evolution in the Therapsida. Journal of Paleontology 77 (5): 977–984.

[TT05] Tverdokhlebov, V. P., G. I. Tverdokhlebova, A. V. Minikh, M. V. Surkov & M. J. Benton. 2005. Upper Permian vertebrates and their sedimentological context in the South Urals, Russia. Earth-Science Reviews 69: 27–77.

Kannemeyeriiformes

Reconstruction of Kannemeyeria, copyright Dmitry Bogdanov.

Belongs within: Dicynodontia.

The Kannemeyeriiformes are a cosmopolitan clade of dicynodonts known from the Triassic, some members of which reached the size of a modern cow. Members of the clade are united by a markedly enlarged preacetabular expansion of the iliac blade, a distinctly offset caput femoris on the femur, and an olecranon ulnae formed by a separate ossification (Maisch 2000).

<==Kannemeyeriiformes
    |--Shansiodontidae M00
    |    |--Vinceria Bonaparte 1967 M00
    |    `--+--Rhinodicynodon Kalandadze 1970 M00
    |       `--+--Shansiodon Yeh 1959 M00
    |          `--Tetragonias Cruickshank 1967 M00
    |               `--T. njalilus M00
    `--+--Kannemeyeriidae M00
       |    |--Rabidosaurus Kalandadze 1970 M00
       |    |--Wadiasaurus Roy-Chowdhury 1970 M00
       |    |    `--W. indicus M00
       |    `--Kannemeyeria Seeley 1908 M00
       |         |--K. erithrea D07
       |         |--K. jenseni D07
       |         `--K. simocephala M00
       `--+--Dinodontosauridae [Dinodontosaurinae, Sinokannemeyeriini] M00
          |    |--Dinodontosaurus Romer 1943 M00
          |    `--+--Sinokannemeyeriinae M00
          |       |    |--Parakannemeyeria Sun 1960 M00
          |       |    `--Sinokannemeyeria Young 1937 M00
          |       `--Rechnisaurinae M00
          |            |  i. s.: Shaanbeikannemeyeria Cheng 1980 M00
          |            |--Rhadiodromus Efremov 1951 (see below for synonymy) M00
          |            `--+--Rechnisaurus Roy-Chowdhury 1970 M00
          |               `--Sangusaurus Cox 1969 M00
          |                    `--S. parringtonii NB17
          `--Stahleckeriidae M00
               |--Stahleckeriinae M00
               |    |--Angonisaurus Cox & Li 1983 M00
               |    |    `--A. cruickshanki NB17
               |    |--Stahleckeria von Huene 1925 [incl. Barysoma Cox 1965] M00
               |    |    `--S. potens von Huene 1935 [incl. S. lenzii Romer & Price 1944, Barysoma lenzii] M00
               |    `--Zambiasaurus Cox 1968 M00
               |         `--Z. submersus M00
               `--Placeriinae M00
                    |--Moghreberia Dutuit 1980 M00
                    |--Placerias Lucas 1904 M00
                    |    `--P. gigas M00
                    `--Ischigualastia Cox 1962 M00
                         `--I. jenseni M00

Kannemeyeriiformes incertae sedis:
  Jachaleria Bonaparte 1971 M00
  Dolichuranus Keyer 1973 M00
  Azarifeneria Dutuit 1989 (n. d.) M00
  Calleonasus Kalandadze 1986 (n. d.) M00
  Edaxosaurus Kalandadze 1986 (n. d.) M00
  Elatosaurus Kalandadze 1986 (n. d.) M00
  Nasoplanites Surkov 1999 M00
  Cristonasus Surkov 1999 M00
  Parvobestiola Surkov 1999 M00
  Planitorostris Surkov 1999 M00

Rhadiodromus Efremov 1951 [incl. Rhinocerocephalus Vjushkov 1969, Uralokannemeyeria Danilov 1971] M00

*Type species of generic name indicated

REFERENCES

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

[M00] Maisch, M. W. 2000. Observations on Karoo and Gondwana vertebrates. Part 2: A new skull-reconstruction of Stahleckeria potens von Huene, 1935 (Dicynodontia, Middle Triassic) and a reconstruction of kannemeyeriiform phylogeny. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 220 (1): 127–152.

[NB17] Nesbitt, S. J., R. J. Butler, M. D. Ezcurra, P. M. Barrett, M. R. Stocker, K. D. Angielczyk, R. M. H. Smith, C. A. Sidor, G. Niedźwiedzki, A. G. Sennikov & A. J. Charig. 2017. The earliest bird-line archosaurs and the assembly of the dinosaur body plan. Nature 544: 484–487.

Ptilodontoidea

Skull of Ptilodus mediaevus, copyright Nobu Tamura.

Belongs within: Cimolodonta.

The Ptilodontoidea are a group of multituberculate mammals known from the Upper Cretaceous to the Eocene of Eurasia and North America, characterised by a very large, arcuate lower rear premolar protruding dorsally above the level of the molars (Kielan-Jaworowska & Hurum 2001).

Characters (from Kielan-Jaworowska & Hurum 2001): Dental formula 2.0.4.2/1.0.2.2; enamel usually microprismatic (gigantoprismatic in Cimolodon); I2 probably single-cusped, I3 placed on margin of premaxilla; lower incisor usually gracile, completely covered with enamel (robust with limited enamel band in Neoliotomus); P4 elongated, shaped as isosceles triangle in lateral view, protruding ventrally over level of anterior premolars and molars; p4 very large, arcuate, strongly protruding dorsally over level of molars; molars with ornamentation of grooves and ridges, cusps tending to coalesce. Snout wide, gently incurved in front of zygomatic arches. Frontals small, pointed posteriorly.

<==Ptilodontoidea
    |--Cimolodontidae K-JH01
    |    |--Anconodon Jepsen 1940 K-JH01
    |    |--Liotomus Cope 1884 K-JH01
    |    `--Cimolodon Marsh 1889 K-JH01
    |         `--C. electus K-JH01
    `--+--Neoliotomus Jepsen 1930 K-JH01
       `--+--Ptilodontidae [Chirogidae] K-JH01
          |    |--Kimbetohia Simpson 1936 K-JH01
          |    |--Prochetodon Jepsen 1940 K-JH01
          |    |--Baiotomeus Krause 1987 SFY02
          |    |    |--B. douglassi (Simpson 1935) SFY02
          |    |    |--B. lamberti Krause 1987 SFY02
          |    |    `--B. russelli Scott, Fox & Youzwyshyn 2002 SFY02
          |    `--Ptilodus Cope 1881 SFY02
          |         |--P. douglassi Simpson 1935 S35b
          |         |--P. fractus Dorr 1952 SFY02
          |         |--P. gidleyi Simpson 1935 S35b
          |         |--P. gnomus Scott, Fox & Youzwyshyn 2002 SFY02
          |         |--P. kummae Krause 1977 SFY02
          |         |--P. mediaevus Cope 1881 SFY02
          |         |--P. montanus Douglass 1908 [incl. P. admirabilis Hay 1930, P. gracilis Gidley 1909 (preoc.)] S35b
          |         |--P. sinclairi Simpson 1935 S35b
          |         |--P. trovessartianus S35b
          |         |--P. tsosiensis Sloan 1981 SFY02
          |         `--P. wyomingensis D07
          `--Neoplagiaulacidae K-JH01
               |--Xyronomys Rigby 1980 K-JH01
               |--Cernaysia Vianey-Liaud 1986 K-JH01
               |--Krauseia Vianey-Liaud 1986 K-JH01
               |--Mesodma Jepsen 1940 K-JH01
               |--Mimetodon Jepsen 1940 K-JH01
               |--Mesodmops Tong & Wang 1994 K-JH01
               |--Xanclomys Rigby 1980 K-JH01
               |--Neoplagiaulax Lemoine 1882 K-JH01
               |    `--N. hazeni K-JH01
               |--Parectypodus Jepsen 1930 K-JH01
               |    |--P. jepseni Simpson 1935 S35b
               |    |--P. laytoni K-JH01
               |    |--P. simpsoni S35b
               |    `--P. tardus S35b
               `--Ectypodus Matthew & Granger 1921 K-JH01
                    |--*E. musculus Matthew & Granger 1921 S35a
                    |--E. cochranensis S35b
                    |--E. grangeri Simpson 1935 S35b
                    |--E. russelli Simpson 1935 S35b
                    |--E. silberlingi Simpson 1935 S35b
                    `--E. tardus K-JH01

*Type species of generic name indicated

REFERENCES

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

[K-JH01] Kielan-Jaworowska, Z., & J. H. Hurum. 2001. Phylogeny and systematics of multituberculate mammals. Palaeontology 44 (3): 389–429.

[SFY02] Scott, C. S., R. C. Fox & G. P. Youzwyshyn. 2002. New earliest Tiffanian (late Paleocene) mammals from Cochrane 2, southwestern Alberta, Canada. Acta Palaeontologica Polonica 47: 691–704.

[S35a] Simpson, G. G. 1935a. The Tiffany fauna, Upper Paleocene. I.—Multituberculata, Marsupialia, Insectivora, and ?Chiroptera. American Museum Novitates 795: 1–19.

[S35b] Simpson, G. G. 1935b. New Paleocene mammals from the Fort Union of Montana. Proceedings of the United States National Museum 83 (2981): 221–244.

Cimolodonta

Lower jaw of Cimexomys, from Palaeos.

Belongs within: Multituberculata.
Contains: Ptilodontoidea.

The Cimolodonta are a group of multituberculate mammals known from the Early Cretaceous to the Eocene, including all multituberculates to survive the end of the Cretaceous (Kielan-Jaworowska & Hurum 2001).

Characters (from Kielan-Jaworowska & Hurum 2001): Enamel prismatic; dental formula 2.0.1–4.2/1.0.1–2.2; I1 absent, I2 single- or two-cusped, I3 small, single-cusped; p1 and p2 absent, p3, if present, peg-like, non-functional; p4 primitively arcuate with oblique ridges, single or no posterobuccal cusp present.

Cimolodonta [Boffiini]
    |--Barbatodon Râdulescu & Samson 1986 K-JH01
    |--Dakotamys Eaton 1995 K-JH01
    |    `--D. malcolmi K-JH01
    |--Bryceomys Eaton 1995 K-JH01
    |    `--B. fumosus K-JH01
    |--Paracimexomys Archibald 1982 K-JH01
    |    |--P. crossi K-JH01
    |    `--P. robinsoni K-JH01
    |--Cimexomys Sloan & van Valen 1965 K-JH0
    |    |--C. antiquus D07
    |    |--C. gratus D07
    |    |--C. gregoryi D07
    |    |--C. hausoi D07
    |    |--C. judithae K-JH01
    |    |--C. magnus D07
    |    `--C. minor D07
    `--+--Boffius Vianey-Liaud 1979 [Boffiidae] K-JH01
       |--Ptilodontoidea K-JH01
       `--Taeniolabidoidea K-JH97
            |--Cimolomyidae K-JH01
            |    |--Meniscoessus Cope 1882 K-JH01
            |    |--Cimolomys Marsh 1889 K-JH01
            |    |--Essonodon Simpson 1927 K-JH01
            |    `--Buginbaatar Kielan-Jaworowska & Sochava 1969 [Buginbaatarinae] K-JH01
            |         `--B. transaltaiensis Kielan-Jaworowska & Sochava 1969 K-JH97
            `--+--Djadochtatherioidea K-JH01
               |--Kogaionidae K-JH01
               |    |--Hainina Vianey-Liaud 1979 K-JH01
               |    `--Kogaionon Râdulescu & Samson 1996 K-JH01
               |--Eucosmodontidae K-JH01
               |    |--Eucosmodon Matthew & Granger 1921 K-JH01
               |    |--Stygimys Sloan & van Valen 1965 K-JH01
               |    `--Clemensodon Krause 1992 K-JH01
               |--Microcosmodontidae K-JH01
               |    |--Microcosmodon Jepsen 1930 K-JH01
               |    |--Pentacosmodon Jepsen 1940 K-JH01
               |    `--Acheronodon Archibald 1982 K-JH01
               `--Taeniolabididae K-JH01
                    |--Prionessus Matthew & Granger 1925 K-JH01
                    |--Sphenopsalis Matthew, Granger & Simpson 1928 K-JH01
                    |--Lambdopsalis Chow & Qi 1978 K-JH01
                    |    `--L. bulla K-JH97
                    |--Catopsalis Cope 1882 K-JH01
                    |    `--C. joyneri K-JH01
                    `--Taeniolabis Cope 1882 K-JH01
                         |--T. lamberti D07
                         |--T. sulcatus D07
                         `--T. taoensis K-JH97

*Type species of generic name indicated

REFERENCES

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

[K-JH97] Kielan-Jaworowska, Z., & J. H. Hurum. 1997. Djadochtatheria - a new suborder of multituberculate mammals. Acta Palaeontologica Polonica 42 (2): 201–242.

[K-JH01] Kielan-Jaworowska, Z., & J. H. Hurum. 2001. Phylogeny and systematics of multituberculate mammals. Palaeontology 44 (3): 389–429.

Eutriconodonta

Reconstruction of Repenomamus giganticus, copyright Nobu Tamura.

Belongs within: Mammalia.

The Eutriconodonta are a group of mammals known from the Jurassic and Cretaceous, characterised by triconodont molars with three laterally compressed cusps in a straight alignment (Luo et al. 2007).

Synapomorphies (from Krause et al. 2014): Dens not fused to axis; lumbar ribs not fused to vertebrae; tarsal spur absent; premaxilla with ventral internarial process present but not connected to nasal; single infraorbital foramen present; ventral opening of minor palatine foramen encircled by palatine and maxilla; postpalatine torus present; internal acoustic meatus cribriform plate absent; ear region with lateral flange narrowly separated from anterior paroccipital process (crista parotica); pterygoparoccipital foramen a laterally open notch; mallear manubrium robust; suture separating basioccipital and exoccipital absent; two lower and upper incisors in each quadrant; I3 with single cusp; seven lower postcanine teeth in each quadrant; four lower premolars in each quadrant; ultimate upper premolar (P5) with metacone present; penultimate lower premolar (p4) with paraconid (cusp b) absent or indistinct; ultimate lower premolar tooth (p5) with hypoconid absent; m1–2 with paracristid longitudinally oriented relative to longitudinal axis of molars; m1–2 with buccal curvature of protoconid (cusp a) at base level equivalent to curvature of paraconid (cusp b) and metaconid (cusp c); m1–2 with metacristid (protocristid), crest between protoconid (cusp a) and metaconid (cusp c) parallel to long axis of lower molars and lower jaw axis; m1 with main cusps of trigonid in single longitudinal row; m1–2 with labiolingual compression of primary functional cusps (at level of cusp base but above cingulid); M1–2 with stylar shelf absent; M1–2 with lingual cingulum discontinuous; dentary movement during power stroke of chewing cycle essentially dorsal (orthal); molar with prevallum/postvallid shearing absent.

<==Eutriconodonta
    |  i. s.: Phascolotherium Owen 1838 CM99
    |         ‘Kotatherium’ yadagirii Prasad & Manhas 1997 A02
    |--+--Amphilestes [Amphilestinae] KH14
    |  `--Gobiconodontidae LK-JC02
    |       |--Gobiconodon Trofimov 1978 KH14, CM99
    |       |    `--G. zofiae HM05
    |       `--Repenomamus Li, Wang et al. 2000 LC07, HM05 [Repenomamidae]
    |            |--R. giganticus Hu, Meng et al. 2005 HM05
    |            `--R. robustus HM05
    `--+--+--Jeholodens jenkinsi KH14, LC07
       |  `--Yanoconodon Luo, Chen et al. 2007 LC07
       |       `--*Y. allini Luo, Chen et al. 2007 LC07
       `--Triconodontidae [Triconodontinae] LK-JC02
            |--Priacodon KH14
            |--Trioracodon LK-JC02
            `--Astroconodon LK-JC02

*Type species of generic name indicated

REFERENCES

[A02] Averianov, A. O. 2002. Early Cretaceous “symmetrodont” mammal Gobiotheriodon from Mongolia and the classification of “Symmetrodonta”. Acta Palaeontologica Polonica 47 (4): 705–716.

[CM99] Cifelli, R. L., & S. K. Madsen. 1999. Spalacotheriid symmetrodonts (Mammalia) from the medial Cretaceous (upper Albian or lower Cenomanian) Mussentuchit local fauna, Cedar Mountain Formation, Utah, USA. Geodiversitas 21 (2): 167–214.

[HM05] Hu, Y., J. Meng, Y. Wang & C. Li. 2005. Large Mesozoic mammals fed on young dinosaurs. Nature 433: 149–152.

[KH14] Krause, D. W., S. Hoffmann, J. R. Wible, E. C. Kirk, J. A. Schultz, W. von Koenigswald, J. R. Groenke, J. B. Rossie, P. M. O'Connor, E. R. Seiffert, E. R. Dumont, W. L. Holloway, R. R. Rogers, L. J. Rahantarisoa, A. D. Kemp & H. Andriamialison. 2014. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature 515: 512–517.

[LC07] Luo, Z.-X., P. Chen, G. Li & M. Chen. 2007. A new eutriconodont mammal and evolutionary development in early mammals. Nature 446: 288–293.

[LK-JC02] Luo, Z.-X., Z. Kielan-Jaworowska & R. L. Cifelli. 2002. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontologica Polonica 47: 1–78.

Trechnotheria

Left upper molars of Tinodon (left one) and Symmetrodontoides canadensis (right two) from Palaeos.

Belongs within: Mammalia.
Contains: Cladotheria.

The Trechnotheria are a clade of mammals defined as the most exclusive clade including Zhangheotherium and crown Theria, with the earliest members known from the late Jurassic. Trechnotherians are characterised by the development of a strong postvallum/prevallid shear between the upper and lower molars (Luo et al. 2002). Basal members of the clade, the Spalacotheroidea and Tinodontidae, have been classified in the past as members of the 'symmetrodonts' but this group of early mammals with triangular molars and reduced talonids is now generally regarded as non-monophyletic.

Synapomorphies (from Luo et al. 2002): Hypertrophied postvallum/prevallid shearing mechanism present, with acute triangulation of molar cusps; petrosal with large post-tympanic recess and caudal tympanic process; epitympanic recess bounded by lateral wall formed by squamosal. Scapula with posterior part of supraspinous fossa relatively expanded, far wider than glenoid region, fossa fan-shaped or triangular in outline; supraspinous fossa wider than infraspinous fossa. Proximo-lateral process of tibia vestigial or absent. Humerus with posterior aspect of distal articulation for radius cylindrical. Calcaneus with sustentacular facet oblique to the horizontal plane (uncertain in Spalacotherioidea).

<==Trechnotheria
    |--Spalacotheroidea [Spalacotheriinae] A02
    |    |  i. s.: Heishanlestes MH06
    |    |--Zhangheotherium Hu et al. 1997 KH14, CM99
    |    |    `--Z. quinquecuspidens Hu et al. 1997 A02
    |    `--+--Akidolestes KH14
    |       `--+--Maotherium KH14
    |          `--Spalacotheriidae A02
    |               |  i. s.: Shalbaatar Nessov 1997 A02
    |               |           `--S. bakht Nessov 1997 A02
    |               |--Spalacotherium Owen 1854 KH14, CM99 [incl. Peralestes Owen 1871 A02]
    |               |    `--S. tricuspedens OB13
    |               `--Spalacolestinae CM99
    |                    |--Spalacotheroides Patterson 1955 CM99
    |                    |    `--S. bridwelli Patterson 1955 CM99
    |                    `--+--Spalacotheridium Cifelli 1990 CM99
    |                       |    |--*S. mckennai Cifelli 1990 CM99
    |                       |    `--S. noblei Cifelli & Madsen 1999 CM99
    |                       `--+--Spalacolestes Cifelli & Madsen 1999 CM99
    |                          |    |--*S. cretulablatta Cifelli & Madsen 1999 CM99
    |                          |    `--S. inconcinnus Cifelli & Madsen 1999 CM99
    |                          `--Symmetrodontoides Fox 1976 CM99 [incl. Mictodon Fox 1984 A02]
    |                               |--*S. canadensis Fox 1976 CM99
    |                               |--S. foxi Cifelli & Madsen 1986 CM99
    |                               |--S. oligodontos Cifelli 1990 CM99
    |                               `--‘Mictodon’ symmetrodontoides Fox 1984 A02
    `--+--Tinodontidae A02
       |    |--Gobiotheriodon Trofimov 1997 A02
       |    |    `--G. infinitus (Trofimov 1980) [=Gobiodon infinitus, Gobiondon (l. c.) infinitus] A02
       |    `--Tinodon Marsh 1879 KH14, A02 [incl. Eurylambda Simpson 1929 A02, Menacodon Marsh 1887 A02]
       |         |--T. bellus Marsh 1879 [incl. T. lepidus Marsh 1879] A02
       |         `--T. micron Ensom & Sigogneau-Russell 2000 A02
       `--Cladotheria LK-JC02

*Type species of generic name indicated

REFERENCES

[A02] Averianov, A. O. 2002. Early Cretaceous “symmetrodont” mammal Gobiotheriodon from Mongolia and the classification of “Symmetrodonta”. Acta Palaeontologica Polonica 47 (4): 705–716.

[CM99] Cifelli, R. L., & S. K. Madsen. 1999. Spalacotheriid symmetrodonts (Mammalia) from the medial Cretaceous (upper Albian or lower Cenomanian) Mussentuchit local fauna, Cedar Mountain Formation, Utah, USA. Geodiversitas 21 (2): 167–214.

[KH14] Krause, D. W., S. Hoffmann, J. R. Wible, E. C. Kirk, J. A. Schultz, W. von Koenigswald, J. R. Groenke, J. B. Rossie, P. M. O'Connor, E. R. Seiffert, E. R. Dumont, W. L. Holloway, R. R. Rogers, L. J. Rahantarisoa, A. D. Kemp & H. Andriamialison. 2014. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature 515: 512–517.

[LK-JC02] Luo, Z.-X., Z. Kielan-Jaworowska & R. L. Cifelli. 2002. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontologica Polonica 47: 1–78.

[MH06] Meng, J., Y. Hu, Y. Wang, X. Wang & C. Li. 2006. A Mesozoic gliding mammal from northeast China. Nature 444 (7121): 889–893.

[OB13] O'Leary, M. A., J. I. Bloch, J. J. Flynn, T. J. Gaudin, A. Giallombardo, N. P. Giannini, S. L. Goldberg, B. P. Kraatz, Z.-X. Luo, J. Meng, X. Ni, M. J. Novacek, F. A. Perini, Z. S. Randall, G. W. Rougier, E. J. Sargis, M. T. Silcox, N. B. Simmons, M. Spaulding, P. M. Velazco, M. Weksler, J. R. Wible & A. L. Cirranello. 2013. The placental mammal ancestor and the post-K–Pg radiation of placentals. Science 339: 662–667.

Last updated: 22 August 2018.

Dicynodontia

Mounted skeleton of Lystrosaurus murrayi in the Muséum national d'histoire naturelle, Paris, photographed by FunkMonk.

Belongs within: Eutherapsida.
Contains: Kannemeyeriiformes.

The Dicynodontia are a group of herbivorous synapsids known from the the Late Permian to the Cretaceous, though they did not survive past the Late Triassic outside Australia. At their peak, they were the world's dominant herbivores. One genus, Lystrosaurus, included the most abundant terrestrial vertebrates in the earliest Triassic immediately following the end-Permian mass extinction. The name 'dicynodont' refers to the pair of large tusks that were generally the only teeth in their beaked jaws.

Synapomorphies (from Kemp 1988): Zygomatic arch dorsally displaced; dentaries fused at symphysis; articular surface of lower jaw sloping posteroventrally; horn developed on the jaws; intramandibular fenestra present; premaxillary secondary palate present.

<==Dicynodontia
    |--Kombuisia M00
    |--Myosaurus M00
    `--Pristerodontia M00
         |  i. s.: Odontocyclops M00
         |--Lystrosaurus Cope 1870 M00, D07 [Lystrosauridae]
         |    |--L. curvatus D07
         |    |--L. declivis D07
         |    |--L. georgi D07
         |    |--L. hedini D07
         |    |--L. mccaigi D07
         |    |--L. murrayi M00
         |    |--L. oviceps D07
         |    |--L. platycopes D07
         |    |--L. rajurkari D07
         |    |--L. robustus D07
         |    |--L. shichanggouensis D07
         |    `--L. weidenrichi D07
         `--+--+--Dinanomodon M00
            |  `--Kannemeyeriiformes M00
            `--Dicynodon Owen 1845 M00, D07 [Dicynodontidae]
                 |--D. bolorhinus D07
                 |--D. grimbeeki D07
                 |--D. lacerticeps M00
                 |--D. leontops D07
                 |--D. lissops D07
                 |--D. osborni D07
                 |--D. plateceps D07
                 |--D. trautscholdi D07
                 |--D. trigonocephalus D07
                 |--D. turpior D07
                 `--D. whaitsi D07

Dicynodontia incertae sedis:
  Cistecephalus Owen 1876 D07
    `--C. microrhinus D07
  Emydoses M00
  Otsheria K88
  Venyukovioidea TT05
    |  i. s.: Suminia getmanovi Ivakhnenko 1994 TT05
    `--Venyukoviidae TT05
         |--Ulemica efremovi Ivakhnenko 1996 TT05
         `--Venjukovia K88
  Aulacocephalodon peavoti N85
  Diictodon Owen 1876 D07
    `--E. feliceps D07

*Type species of generic name indicated

REFERENCES

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

[K88] Kemp, T. S. 1988. Interrelationships of the Synapsida. In: Benton, M. J. (ed.) The Phylogeny and Classification of the Tetrapods vol. 2. Mammals pp. 1–22. Clarendon Press: Oxford.

[M00] Maisch, M. W. 2000. Observations on Karoo and Gondwana vertebrates. Part 2: A new skull-reconstruction of Stahleckeria potens von Huene, 1935 (Dicynodontia, Middle Triassic) and a reconstruction of kannemeyeriiform phylogeny. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 220 (1): 127–152.

[N85] Norman, D. 1985 (reprinted 2000). The Illustrated Encyclopedia of Dinosaurs. Salamander Books: London.

[TT05] Tverdokhlebov, V. P., G. I. Tverdokhlebova, A. V. Minikh, M. V. Surkov & M. J. Benton. 2005. Upper Permian vertebrates and their sedimentological context in the South Urals, Russia. Earth-Science Reviews 69: 27–77.

Last updated: 24 August 2018.

Cynodontia

Skull of Diademodon mastacus on display at the Museum für Naturkunde, Berlin, photographed by FunkMonk.

Belongs within: Eutherapsida.
Contains: Mammaliaformes.

The clade Cynodontia, incluing modern mammals and a number of related non-mammalian synapsids, was defined by Hopson & Kitching (2001) as the most inclusive clade including Mammalia and excluding Bauria. Though the group was ancestrally carnivorous, herbivory evolved among the cynodonts in the Gomphodontia and the Tritylodontidae (as well as several times within the mammals). Cynodonts are first known from the Late Permian, where they are represented by Dvinia and the Procynosuchidae. The remaining cynodonts form a clade Epicynodontia, defined as all taxa closer to mammals than Procynosuchidae and united by synapomorphies including a dentary-surangular dorsal contact midway between the postorbital bar and jaw joint, a coronoid process on the dentary extending above the middle of the orbit, four upper incisors and three lower incisors (Hopson & Kitching 2001).

Characters (from Hopson & Kitching 2001): Nasal-lacrimal contact present; postfrontal absent; prefrontal-postorbital contact present; ectopterygoid not in contact with maxilla; palatal exposure of maxilla behind canine greater than 20% distance from canine to posterior end of palatine; secondary palatal plate on maxilla and palatine; pterygoid flange without teeth; tabular extending around posttemporal foramen; groove on prootic extending from pterygoparoccipital foramen to trigemimal foramen; trigeminal nerve exiting via foramen between prootic and epipterygoid; posteroventral process on quadrate in posterior notch of squamosal; ascending process of epipterygoid greatly expanded; epipterygoid overlapping prootic; lateral flange present on prootic; epipterygoid in contact with frontal; double occipital condyles; stapedial foramen with dorsoventral orientation; dentary masseteric fossa present high on coronoid region; dentary overlap of surangular long; reflected lamina of angula spoon-shaped plate; incisor cutting margins smoothly ridged; canine serrations absent; postcanines with two or more cusps in line; lower anterior cingulum or cusp present; anterior process of ilium 1.0 to 1.5 times diameter of acetabulum; pubis between 1.5 and 1.0 times acetabular diameter.

<==Cynodontia
    |  i. s.: Chaliminia LCS01
    |         Lepagia DDL04
    |         Chronoperates paradoxus Fox, Youzwyshyn & Krause 1992 SFY02
    |--Dvinia HK01
    `--+--Procynosuchidae TT05
       |    |--Uralocynodon tverdochlebovae (Tatarinov 1987) TT05
       |    `--Procynosuchus Broom 1931 MH06, D07
       |         |--P. delaharpeae D07
       |         `--P. rubidgei D07
       `--Epicynodontia HK01
            |--Galesaurus HK01
            `--+--Thrinaxodon Seeley 1894 MH06, D07 [Thrinaxodontidae]
               |    `--T. liorhinus HK01
               `--Eucynodontia [Mammaliamorpha, Tritylodontoidea] HK01
                    |--Cynognathia HK01
                    |    |--Cynognathus Seeley 1895 HK01, D07 [Cynognathidae]
                    |    |    `--C. crateronotus HK01
                    |    `--Gomphodontia [Diademodontidae] HK01
                    |         |--Diademodon mastacus HK01
                    |         `--+--Trirachodon HK01
                    |            `--+--Pascualgnathus HK01
                    |               `--+--Scalenodon angustifrons HK01
                    |                  `--+--Luangwa HK01
                    |                     `--Traversodontidae D07
                    |                          |--Massetognathus Romer 1967 HK01, D07
                    |                          |    |--M. ochagaviae D07
                    |                          |    `--M. pascuali D07
                    |                          `--+--‘Scalenodon’ hirschoni HK01
                    |                             `--+--Exaeretodon HK01
                    |                                `--Gomphodontosuchus HK01
                    `--Probainognathia HK01
                         |--Lumkuia Hopson & Kitching 2001 [Lumkuiidae] HK01
                         |    `--*L. fuzzi Hopson & Kitching 2001 HK01
                         `--+--Ecteninion HK01
                            `--+--+--Probainognathus [Probainognathidae] LY11
                               |  |    `--P. jenseni HK01
                               |  `--+--Pachygenelus [Tritheledontidae] LY11
                               |     |    `--P. monus Watson 1913 OB13
                               |     `--+--Mammaliaformes LY11
                               |        |--+--Brasilodon MH06
                               |        |  `--Brasilitherium MH06
                               |        `--Tritylodontidae LY11
                               |             |  i. s.: Tritylodon longaevus Owne 1884 OB13
                               |             |--Kayentatherium KH14
                               |             |--Yunnanodon KH14
                               |             |--+--Bienotherium KH14
                               |             |  `--Oligokyphus Hennig 1922 KH14, D07
                               |             |       |--O. major [incl. O. minor] D07
                               |             |       `--O. triserialis D07
                               |             `--+--Bocatherium KH14
                               |                `--Bienotheroides KH14
                               `--Chiniquodontoidea DDL04
                                    |--Chiniquodontidae HK01
                                    |    |--Probelesodon HK01
                                    |    `--+--Aleodon brachyrhamphus HK01, NS10
                                    |       `--Chiniquodon von Huene 1936 MH06, D07
                                    |            |--C. magnificus D07
                                    |            |--C. sanjuanensis D07
                                    |            `--C. theotonicus D07
                                    `--+--+--Therioherpeton DDL04
                                       |  `--Charruodon DDL04
                                       `--Dromatheriidae DDL04
                                            |--Microconodon tenuirostris [=Dromatherium tenuirostris] DDL04
                                            |--Tricuspes DDL04
                                            |--Meurthodon DDL04
                                            |--Rewaconodon Datta, Das & Luo 2004 DDL04
                                            |    `--*R. tikiensis Datta, Das & Luo 2004 DDL04
                                            `--Pseudotriconodon DDL04
                                                 |--P. chatterjeei Lucas & Oakes 1988 DDL04
                                                 `--P. wildi DDL04

*Type species of generic name indicated

REFERENCES

[DDL04] Datta, P. M., D. P. Das & Z.-X. Luo. 2004. A Late Triassic dromatheriid (Synapsida: Cynodontia) from India. Annals of Carnegie Museum 73 (2): 12–24.

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

[HK01] Hopson, J. A., & J. W. Kitching. 2001. A probainognathian cynodont from South Africa and the phylogeny of nonmammalian cynodonts. Bulletin of the Museum of Comparative Zoology 156 (1): 5–35.

[KH14] Krause, D. W., S. Hoffmann, J. R. Wible, E. C. Kirk, J. A. Schultz, W. von Koenigswald, J. R. Groenke, J. B. Rossie, P. M. O'Connor, E. R. Seiffert, E. R. Dumont, W. L. Holloway, R. R. Rogers, L. J. Rahantarisoa, A. D. Kemp & H. Andriamialison. 2014. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature 515: 512–517.

[LCS01] Luo, Z.-X., A. W. Crompton & A.-L. Sun. 2001. A new mammaliaform from the Early Jurassic and evolution of mammalian characteristics. Science 292: 1535–1540.

[LY11] Luo, Z.-X., C.-X. Yuan, Q.-J. Meng & Q. Ji. 2011. A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476: 442–445.

[MH06] Meng, J., Y. Hu, Y. Wang, X. Wang & C. Li. 2006. A Mesozoic gliding mammal from northeast China. Nature 444 (7121): 889–893.

[NS10] Nesbitt, S. J., C. A. Sidor, R. B. Irmis, K. D. Angielczyk, R. M. H. Smith & L. A. Tsuji. 2010. Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira. Nature 464: 95–98.

[OB13] O'Leary, M. A., J. I. Bloch, J. J. Flynn, T. J. Gaudin, A. Giallombardo, N. P. Giannini, S. L. Goldberg, B. P. Kraatz, Z.-X. Luo, J. Meng, X. Ni, M. J. Novacek, F. A. Perini, Z. S. Randall, G. W. Rougier, E. J. Sargis, M. T. Silcox, N. B. Simmons, M. Spaulding, P. M. Velazco, M. Weksler, J. R. Wible & A. L. Cirranello. 2013. The placental mammal ancestor and the post-K–Pg radiation of placentals. Science 339: 662–667.

[SFY02] Scott, C. S., R. C. Fox & G. P. Youzwyshyn. 2002. New earliest Tiffanian (late Paleocene) mammals from Cochrane 2, southwestern Alberta, Canada. Acta Palaeontologica Polonica 47: 691–704.

[TT05] Tverdokhlebov, V. P., G. I. Tverdokhlebova, A. V. Minikh, M. V. Surkov & M. J. Benton. 2005. Upper Permian vertebrates and their sedimentological context in the South Urals, Russia. Earth-Science Reviews 69: 27–77.

Last updated: 24 August 2018.