Palaeanodonta

Palaeanodonta ("ancient toothless animals") is an extinct clade of stem-pangolins. They were insectivorous, possibly fossorial, and lived from the Early Paleocene to Early Oligocene in North America, Europe and East Asia.[4][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]

Palaeanodonta
Temporal range: 63.8–30.9 Ma Early Paleocene – Early Oligocene
Palaeanodonta.jpg
From top to bottom: Ernanodon antelios, Xenocranium pileorivale and Metacheiromys marshi
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Clade: Pholidotamorpha
Order: Palaeanodonta
Matthew, 1918[1]
Families and genera
Synonyms
list of synonyms:
  • Ernodonta (Ding, 1987)
  • Ernanodonta (Ding, 1987)
  • Palaeanodontiformes (Kinman, 1994) [2]
  • Palaenodontina (Pearse, 1936)[3]

AnatomyEdit

SkullEdit

Palaeanodonts generally have low and caudally-broad skulls, with notable lambdoid crests and inflated bullae and squamosals.[4]

TeethEdit

Despite the name of the group and contrary to their pangolin relatives, palaeanodonts are known to have had teeth.[11][4][10] Early palaeanodonts retained minimal tribosphenic post-canines while later species had peglike or otherwise reduced molar crowns.[11][4][10] Many also had large, characteristic cuspids.[11][10]

Classification and phylogenyEdit

Traditional classificationEdit

Revised classificationEdit

  • Order: †Palaeanodonta (Matthew, 1918) (stem-pangolins)[6]
    • Family: †Epoicotheriidae (Simpson, 1927)
      • Genus: †Alocodontulum (Rose, 1978)
        • Alocodontulum atopum (Rose, 1977)
      • Genus: †Auroratherium (Tong & Wang, 1997)
        • Auroratherium sinense (Tong & Wang, 1997)
      • Genus: †Dipassalus (Rose, 1991)
        • Dipassalus oryctes (Rose, 1991)
      • Genus: †Pentapassalus (Gazin, 1952)
        • Pentapassalus pearcei (Gazin, 1952)
        • Pentapassalus woodi (Guthrie, 1967)
      • Genus: †Tubulodon (Jepsen, 1932)
        • Tubulodon taylori (Jepsen, 1932)
      • Subfamily: †Epoicotheriinae (Simpson, 1927)
        • Genus: †Epoicotherium (Simpson, 1927)
          • Epoicotherium unicum (Douglass, 1905)
        • Genus: †Molaetherium (Storch & Rummel, 1999)
          • Molaetherium heissigi (Storch & Rummel, 1999)
        • Genus: †Tetrapassalus (Simpson, 1959)
          • Tetrapassalus mckennai (Simpson, 1959)
          • Tetrapassalus proius (West, 1973)
        • 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)
        • Metacheiromys dasypus (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)
      • Subfamily: †Propalaeanodontinae (Schoch, 1984)
        • Genus: †Propalaeanodon (Rose, 1979)
          • Palaeanodon parvulus (Rose, 1979)
    • Incertae sedis:
      • Genus: †Amelotabes (Rose, 1978)
        • Amelotabes simpsoni (Rose, 1978)
      • Genus: †Arcticanodon (Rose, 2004)
        • Arcticanodon dawsonae (Rose, 2004)
      • Genus: †Melaniella (Fox, 1984)
        • Melaniella timosa (Fox, 1984)

Phylogenetic treeEdit

The phylogenetic relationships of Palaeanodonta are shown in the following cladogram:[4][5][6]

 Pholidotamorpha 

Pholidota (sensu stricto)  

 †Palaeanodonta 

Escavadodontidae

 ? 

Amelotabes

 ? 

Melaniella

Epoicotheriidae

 ? 

Arcticanodon

Metacheiromyidae

Propalaeanodontinae

Mylanodon

Brachianodon

Palaeanodon

Metacheiromys  

Ernanodontidae

Metacheiromyinae
 (Pholidota [sensu lato]) 

ReferencesEdit

  1. ^ 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
  2. ^ 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"
  3. ^ 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
  4. ^ a b c d e f 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.
  5. ^ 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.
  6. ^ 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.
  7. ^ Averianov, A. O. & Lopatin, A. V. (2014.) "High-level systematics of placental mammals: Current status of the problem." Biology Bulletin, 41(9), 801–816.
  8. ^ 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.
  9. ^ 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.
  10. ^ 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.
  11. ^ 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.