Palaeanodonta Explained

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.^[1] While the taxonomic grouping of Palaeanodonta has been debated,^[2] it is widely thought that they are a sister group to pangolins.^{[3] [4] [5] [6]}

Anatomy

Skull

Palaeanodonts generally have low and caudally-broad skulls, with notable lambdoid crests and inflated bullae and squamosals.^[7]

Teeth

Despite the name of the group and contrary to their pangolin relatives, palaeanodonts are known to have had teeth.^[8] Early palaeanodonts retained minimal tribosphenic post-canines while later species had peglike or otherwise reduced molar crowns. Many also had large, characteristic cuspids.

Classification and phylogeny

Traditional classification

• Order: †Palaeanodonta (Matthew, 1918) (stem-pangolins)^[7]
  • 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)^[1]
  • 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)[1]} (Wortman, 1903)
    • Genus: †Brachianodon (Gunnell & Gingerich, 1993)
      • †Brachianodon westorum (Gunnell & Gingerich, 1993)
    • Genus: †Mylanodon (Secord, 2002)
      • †Mylanodon rosei (Secord, 2002)
    • Subfamily: †Metacheiromyinae ^{(paraphyletic subfamily)[1]} (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:^{[7] [5] [1]}

See also

• Mammal classification
• Pholidotamorpha

Notes and References

1. Kondrashov . Peter . Agadjanian . Alexandre K. . A nearly complete skeleton of Ernanodon (Mammalia, Palaeanodonta) from Mongolia: morphofunctional analysis . Journal of Vertebrate Paleontology . 32 . 5 . 2012 . 0272-4634 . 10.1080/02724634.2012.694319 . 983–1001.
2. Averianov, A. O. & Lopatin, A. V. (2014.) "High-level systematics of placental mammals: Current status of the problem." Biology Bulletin, 41(9), 801–816.
3. Book: McKenna . M. C. . Bell . S. K. . Classification of Mammals: Above the Species Level . 220-221 . Columbia University Press . 978-0-231-52853-5 . 1997.
4. Book: The Rise of Placental Mammals. Origins and Relationships of the Major Extant Clades . Rose . K. D. . Emry . R. J. . Gaudin . T. J. . Storch . G. . Xenarthra and Pholidota . 2005 . Rose . K. D. . Archibald . J. D. . 106-126 . Johns Hopkins University Press . 978-0-8018-8022-3.
5. Gaudin . T. J. . Emry . R. J. . Wible . J. R. . The Phylogeny of Living and Extinct Pangolins (Mammalia, Pholidota) and Associated Taxa: A Morphology Based Analysis . Journal of Mammalian Evolution . 16 . 235 . 2009 . 10.1007/s10914-009-9119-9.
6. Book: Ungar, P. S. . Mammal Teeth: Origin, Evolution, and Diversity . Cenozoic Mammal Evolution . 110-126 . 978-0-8018-9668-2 . 2010 . Peter Ungar.
7. Book: Rose, K. D. . 9. Palaeanodonta and Pholidota . Evolution of Tertiary Mammals of North America . 2008 . 135-146 . Cambridge University Press . 10.1017/CBO9780511541438.010 . C. M. . Janis . G. F. . Gunnell . M. D. . Uhen.
8. Rose . K. D. . Lucas . S. G. . An early Paleocene palaeanodont (Mammalia, ?Pholidota) from New Mexico, and the origin of Palaeanodonta . Journal of Vertebrate Paleontology . 20 . 1 . 2000 . 10.1671/0272-4634(2000)020[0139:AEPPMP]2.0.CO;2 . 139-156.