Ennatosaurus

Ennatosaurus
Temporal range: 270–265 Ma
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Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: †Caseasauria
Family: †Caseidae
Genus: †Ennatosaurus
Efremov, 1956
Type species
Ennatosaurus tecton
Efremov, 1956

Ennatosaurus is an extinct genus of caseid synapsid that lived during the Middle Permian (late Roadian - early Wordian) in northern European Russia.[1] The genus is only represented by its type species, Ennatosaurus tecton, which was named in 1956 by Ivan Antonovich Efremov.[2] The species is known from at least six skulls associated with their lower jaws (two of them preserved with the hyoid apparatus), as well as from the postcranial bones of several juvenile individuals.[3][4][5] Ennatosaurus has the typical caseid skull with a short snout tilted forward and very large external nares. However, it differs from other derived caseids by its postcranial skeleton with smaller proportions compared to the size of the skull.[3][5] As with other advanced caseids, the teeth of Ennatosaurus were well suited for slicing and cutting vegetation.[3] The presence of a highly developed hyoid apparatus indicates the presence of a massive and mobile tongue, which had to work in collaboration with the palatal teeth during swallowing.[3][6] With a late Roadian - early Wordian age, Ennatosaurus is one of the last known caseids[1] (with Lalieudorhynchus from southern France).

  1. ^ a b Golubev, V.K. (2015). "Dinocephalian Stage in the History of the Permian Tetrapod Fauna of Eastern Europe". Paleontological Journal. 49 (12): 1346–1352. doi:10.1134/S0031030115120059. S2CID 130694755.
  2. ^ Efremov, I.A. (1956). "[American elements in the fauna of Permian reptiles of the U.S.S.R.]". Doklady Akademii Nauk SSSR. 111 (5): 1091-1094 [in Russian].
  3. ^ a b c d Olson, E.C. (1968). "The family Caseidae". Fieldiana: Geology. 17: 225–349.
  4. ^ Maddin, H.C.; Sidor, C.A.; Reisz, R.R. (2008). "Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae". Journal of Vertebrate Paleontology. 28 (1): 160–180. doi:10.1671/0272-4634(2008)28[160:CAOETS]2.0.CO;2. S2CID 44064927.
  5. ^ a b Romano, M.; Brocklehurst, N.; Fröbisch, J. (2017). "The postcranial skeleton of Ennatosaurus tecton (Synapsida, Caseidae)". Journal of Systematic Palaeontology. 16 (13): 1097–1122. doi:10.1080/14772019.2017.1367729. S2CID 89922565.
  6. ^ Kemp, T.S. (2005). The Origin & Evolution of Mammals. Oxford University Press. p. 22. ISBN 978-0198507611.