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Palaeanodonta; Temporal range: 62.22–30.9 Ma PreꞒ Ꞓ O S D C P T J K Pg N Middle Paleocene – Early Oligocene
	From top to bottom: Ernanodon antelios, Xenocranium pileorivale and Metacheiromys marshi
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Clade:	Pholidotamorpha
Order:	†Palaeanodonta; Matthew, 1918
Families and genera
	[see classification]
Synonyms
	list of synonyms: Ernodonta (Ding, 1987) ; Ernanodonta (Ding, 1987) ; Palaeanodontiformes (Kinman, 1994) ; Palaenodonta (Rose, 2008) ; Palaenodontina (Pearse, 1936) ;

Palaeanodonta ("ancient toothless animals") is an extinct clade of stem-pangolins. They were insectivorous (myrmecophagous), possibly fossorial, and lived from the middle Paleocene to early Oligocene in North America, Europe and Asia.^[3]^[5]^[6] While the taxonomic grouping of Palaeanodonta has been debated,^[7] it is widely thought that they are a sister group to pangolins.^[8]^[9]^[5]^[10]

Anatomy

Skull

Palaeanodonts generally have low and caudally-broad skulls, with notable lambdoid crests and inflated bullae and squamosals.^[3]

Teeth

Despite the name of the group and contrary to their pangolin relatives, palaeanodonts are known to have had teeth.^[11]^[3]^[10] Early palaeanodonts retained minimal tribosphenic post-canines while later species had peglike or otherwise reduced molar crowns.^[11]^[3]^[10] Many also had large, characteristic cuspids.^[11]^[10]

Classification and phylogeny

Traditional classification

Order: †Palaeanodonta (Matthew, 1918) (stem-pangolins)^[3]
- Family: †Epoicotheriidae ^{(paraphyletic family)} (Simpson, 1927)
- Family: †Escavadodontidae (Rose & Lucas, 2000)
- Family: †Metacheiromyidae (Wortman, 1903)
- Incertae sedis:
  - Genus: †Arcticanodon (Rose, 2004)
  - Genus: †Melaniella (Fox, 1984)

Revised classification

Order: †Palaeanodonta (Matthew, 1918) (stem-pangolins)^[6]
- Family: †Epoicotheriidae ^{(paraphyletic family)} (Simpson, 1927)
  - Genus: †Alocodontulum (Rose, 1978)
    - †Alocodontulum atopum (Rose, 1977)
  - Genus: †Amelotabes (Rose, 1978)
    - †Amelotabes simpsoni (Rose, 1978)
  - Genus: †Auroratherium (Tong & Wang, 1997)
    - †Auroratherium sinense (Tong & Wang, 1997)
  - Genus: †Dipassalus (Rose, 1991)
    - †Dipassalus oryctes (Rose, 1991)
  - Genus: †Tubulodon (Jepsen, 1932)
    - †Tubulodon taylori (Jepsen, 1932)
  - Subfamily: †Epoicotheriinae ^{(paraphyletic subfamily)} (Simpson, 1927)
    - Genus: †Pentapassalus (Gazin, 1952)
      - †Pentapassalus pearcei (Gazin, 1952)
      - †Pentapassalus woodi (Guthrie, 1967)
    - Genus: †Tetrapassalus (Simpson, 1959)
      - †Tetrapassalus mckennai (Simpson, 1959)
      - †Tetrapassalus proius (West, 1973)
      - †Tetrapassalus sp. A [AMNH 10215] (Rose, 1978)
      - †Tetrapassalus sp. B (Robinson, 1963)
    - (unranked): †Epoicotherium/Xenocranium clade
      - Genus: †Epoicotherium (Simpson, 1927)
        †Epoicotherium unicum (Douglass, 1905)
      - Genus: †Molaetherium (Storch & Rummel, 1999)
        †Molaetherium heissigi (Storch & Rummel, 1999)
      - Genus: †Xenocranium (Colbert, 1942)
        †Xenocranium pileorivale (Colbert, 1942)
- Family: †Ernanodontidae (Ting, 1979)
  - Genus: †Asiabradypus (Nessov, 1987)
    - †Asiabradypus incompositus (Nessov, 1987)
  - Genus: †Ernanodon (Ting, 1979)
    - †Ernanodon antelios (Ting, 1979)
- Family: †Escavadodontidae (Rose & Lucas, 2000)
  - Genus: †Escavadodon (Rose & Lucas, 2000)
    - †Escavadodon zygus (Rose & Lucas, 2000)
- Family: †Metacheiromyidae ^{(paraphyletic family)^[6]} (Wortman, 1903)
  - Genus: †Brachianodon (Gunnell & Gingerich, 1993)
    - †Brachianodon westorum (Gunnell & Gingerich, 1993)
  - Genus: †Mylanodon (Secord, 2002)
    - †Mylanodon rosei (Secord, 2002)
  - Subfamily: †Metacheiromyinae ^{(paraphyletic subfamily)^[6]} (Wortman, 1903)
    - Genus: †Metacheiromys (Wortman, 1903)
      - †Metacheiromys dasypus (Osborn, 1904)
      - †Metacheiromys marshi (Wortman, 1903)
    - Genus: †Palaeanodon (Matthew, 1918)
      - †Palaeanodon ignavus (Matthew, 1918)
      - †Palaeanodon nievelti (Gingerich, 1989)
      - †Palaeanodon parvulus (Matthew, 1918)
      - †Palaeanodon sp. [Le Quesnoy] (Gheerbrant, 2005)
  - Subfamily: †Propalaeanodontinae (Schoch, 1984)
    - Genus: †Propalaeanodon (Rose, 1979)
      - †Palaeanodon parvulus (Rose, 1979)
- Incertae sedis:
  - Genus: †Arcticanodon (Rose, 2004)
    - †Arcticanodon dawsonae (Rose, 2004)
  - Genus: †Melaniella (Fox, 1984)
    - †Melaniella timosa (Fox, 1984)

Phylogenetic tree

The phylogenetic relationships of order Palaeanodonta are shown in the following cladogram:^[3]^[5]^[6]

Ferae

Pan-Carnivora

Pholidotamorpha

Pholidota (sensu stricto)

†Palaeanodonta

†Escavadodontidae

?

†Melaniella

†Amelotabes

†Epoicotheriidae

	†Epoicotherium

	†Molaetherium

†Xenocranium

†Epoicotheriinae

†Tetrapassalus

†Dipassalus

†Alocodontulum

†Auroratherium

†Pentapassalus

†Tubulodon

?

†Arcticanodon

†Propalaeanodontinae

†Mylanodon

†Brachianodon

†Palaeanodon

†Metacheiromyinae

	†Metacheiromys

	†Ernanodontidae

(Pholidota sensu lato)

†Epoicotherium/Xenocranium clade

†Metacheiromyidae

References

^ W. D. Matthew (1918.) "A revision of the Lower Eocene Wasatch and Wind River faunas. Part V. Insectivora (Continued), Glires, Edentata." Bulletin of the American Museum of Natural History 38(16):429-483
^ Kenneth E. Kinman (1994.) "The Kinman system: toward a stable cladisto-eclectic classification of organisms: living and extinct, 48 phyla, 269 classes, 1,719 orders"
^ ^a ^b ^c ^d ^e ^f ^g Rose, K. D. (2008). "9. Palaeanodonta and Pholidota". In Janis, C. M.; Gunnell, G. F.; Uhen, M. D. (eds.). Evolution of Tertiary Mammals of North America. Cambridge University Press. pp. 135–146. doi:10.1017/CBO9780511541438.010.
^ Arthur Sperry Pearse (1936.) "Zoological names. A list of phyla, classes, and orders, prepared for section F, American Association for the Advancement of Science" American Association for the Advancement of Science
^ ^a ^b ^c Gaudin, T. J.; Emry, R. J.; Wible, J. R. (2009). "The Phylogeny of Living and Extinct Pangolins (Mammalia, Pholidota) and Associated Taxa: A Morphology Based Analysis". Journal of Mammalian Evolution. 16: 235. doi:10.1007/s10914-009-9119-9.
^ ^a ^b ^c ^d ^e Kondrashov, Peter; Agadjanian, Alexandre K. (2012). "A nearly complete skeleton of Ernanodon (Mammalia, Palaeanodonta) from Mongolia: morphofunctional analysis". Journal of Vertebrate Paleontology. 32 (5): 983–1001. doi:10.1080/02724634.2012.694319. ISSN 0272-4634.
^ Averianov, A. O. & Lopatin, A. V. (2014.) "High-level systematics of placental mammals: Current status of the problem." Biology Bulletin, 41(9), 801–816.
^ McKenna, M. C.; Bell, S. K. (1997). Classification of Mammals: Above the Species Level. Columbia University Press. pp. 220–221. ISBN 978-0-231-52853-5.
^ Rose, K. D.; Emry, R. J.; Gaudin, T. J.; Storch, G. (2005). "Xenarthra and Pholidota". In Rose, K. D.; Archibald, J. D. (eds.). The Rise of Placental Mammals. Origins and Relationships of the Major Extant Clades. Johns Hopkins University Press. pp. 106–126. ISBN 978-0-8018-8022-3.
^ ^a ^b ^c ^d Ungar, P. S. (2010). "Cenozoic Mammal Evolution". Mammal Teeth: Origin, Evolution, and Diversity. pp. 110–126. ISBN 978-0-8018-9668-2.
^ ^a ^b ^c Rose, K. D.; Lucas, S. G. (2000). "An early Paleocene palaeanodont (Mammalia, ?Pholidota) from New Mexico, and the origin of Palaeanodonta". Journal of Vertebrate Paleontology. 20 (1): 139–156. doi:10.1671/0272-4634(2000)020[0139:AEPPMP]2.0.CO;2.