Docodonta

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Docodonts
Temporal range: Middle Jurassic–Early Cretaceous
Docodon.png
Life restoration of a Docodon
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Order: Therapsida
Suborder: Cynodontia
Clade: Mammaliaformes
Clade: Docodonta
Kretzoi, 1946
Genera

Docodonta is an order of extinct mammaliaforms that lived during the mid- to late-Mesozoic era. Their most distinguishing physical features were their relatively sophisticated molar teeth, from which the order gets its name. Until recently, Docodonta were represented primarily by isolated teeth and bits of jawbones, with most of these specimens found across former Laurasia (modern-day North America, Europe, and Asia). One disputed docodont has been described from Gondwana (modern-day India and Southern Hemisphere).[1] However, recent discoveries in China have included some exceptionally well preserved, almost complete body fossils[2][3]

Docodonts were traditionally thought to have been primarily ground dwelling and insectivorous, but Castorocauda[4] and possibly Haldanodon[5][6] were specialised for a semi-aquatic lifestyle. Castorocauda also had recurved molars, which suggests possible fish or aquatic invertebrate diet, and a flattened tail.[4] It was thought likely that many docodonts had tendencies towards semi-aquatic habits, given their presence in wetland environments.[7] However, recent discoveries such as the specialised digging species Docofossor,[2] and specialised tree-dweller Agilodocodon[3] suggest Docodonta is more ecologically diverse than previously suspected. Docofossor shows many of the same physical traits as the modern day golden mole, such as wide, shortened digits in the hands for digging.

Taxonomy[edit]

Docodonts are not as closely related to the placentals and marsupials as the monotremes, and are not included in the crown-group mammals. The complexity of their molars and the fact that they possess the dentary-squamosal jaw joint, means that they were previously sometimes regarded as belonging to Mammalia. Some authors limit the term "Mammalia" to the crown group, which excludes mammaliaforms like the docodonts. They are considered to be closer to Mammalia than many other early mammalian groups such as Morganucodonta, Kuehneotheriidae, Haramiyida and Sinoconodon.

See also[edit]

References[edit]

  1. ^ a b Prasad, G. V. R., and B. K. Manhas. 2001 First docodont mammals of Laurasian affinities from India. Current Science, 81:1235-1238.
  2. ^ a b c Luo, Z., Meng, Q., Ji, Q., Liu, D., Zhang, Y., Neander, A. I. 2015 Evolutionary development in basal mammaliaformes as revealed by a docodontan. Science, 347, 6223, 760-764
  3. ^ a b c Meng, Q., Ji, Q., Zhang, Y., Liu, D., Grossnickle, D. M., and Luo, Z. 2015 An arboreal docodont from the Jurassic and mammaliaform ecological diversification. Science, 347, 6223, 760-764.
  4. ^ a b c Ji, Q., Luo, Z., Yuan, C. and Tabrum, A. R. 2006 A swimming Mammaliaform from the Middle Jurassic and ecomorphological diversification of early mammals. Science, 311, 1123-1127.
  5. ^ a b Kühne W. G. and Krusat, G. 1972. Legalisierung des Taxon Haldanodon (Mammalia, Docodonta). Neues Jahrbuch für Geologie Monatshefte 1972:300-302
  6. ^ Krusat, G. 1991 Functional morphology of Haldanodon exspectatus (Mammalia, Docodonta) from the Upper Jurassic of Portugal. Fifth Symposium on Mesozoic Terrestrial Ecosystems and Biota.
  7. ^ Paleontology and Geology of the Upper Jurassic Morrison Formation: Bulletin 36
  8. ^ Mikko's Phylogeny Archive [1] Haaramo, Mikko (2007). "Docodonta - docodonts". Retrieved 30 December 2015. 
  9. ^ Paleofile.com (net, info) "Archived copy". Archived from the original on 2016-01-11. Retrieved 2015-12-30. . "Taxonomic lists- Mammals". Retrieved 30 December 2015. 
  10. ^ Waldman, M and Savage, R.J.G 1972 The first Jurassic mammal from Scotland. Journal of the Geological Society of London 128:119-125
  11. ^ Rougier, G. W., and Apesteguia, S. 2004 The Mesozoic radiation of dryolestids in South America: dental and cranial evidence. Journal of Vertebrate Palaeontology, 24 (Supplement to No. 3):106A.

External links[edit]