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.