Entotympanic

The entotympanic is a bone found in the ear region of many placental mammals. When present it forms the medioventral part of the auditory bulla; it is a neomorphic element derived from the tubal cartilage and the sheath of the tympanohyal. It is found in a wide variety of placental mammals, including Xenarthra, Afroinsectophilia, Hyracoidea, Pholidota, Carnivora, Perissodactyla, Chiroptera, Dermoptera, and Scandentia; it is (apparently secondarily) reduced or absent in Glires, Primates, Eulipotyphla, and Artiodactyla (including Cetacea). [1] It is the only common neomorphic element of the mammalian skull.[2]

The entotympanic contacts the ectotympanic, with which it makes up the auditory bulla.[1]

References

  1. ^ a b Maier, Wolfgang (August 2013). "The entotympanic in late fetal artiodactyla (Mammalia)". Journal of Morphology. 274 (8): 926–939. doi:10.1002/jmor.20149. ISSN 0362-2525.
  2. ^ Koyabu, Daisuke (2023-07-03). "Evolution, conservatism and overlooked homologies of the mammalian skull". Philosophical Transactions of the Royal Society B: Biological Sciences. 378 (1880). doi:10.1098/rstb.2022.0081. ISSN 0962-8436. PMC 10184252. PMID 37183902.
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Bones in the tetrapod skeleton
Cranium
Skull roof
Composite bones
Braincase
Composite bones
  • Occipital (Supraoccipital+Exoccipital+Basioccipital)
  • Otoccipital (Exoccipital+Opisthotic)
  • Parabasisphenoid (Parasphenoid+Basisphenoid)
  • Petrosal (Prootic+Opisthotic)
  • Temporal (Squamosal+Petrosal+Ectotympanic)
Palate
Mandible
Hyoid
Postcranial skeleton
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Vertebrae
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Appendicular
Pectoral girdle
Forelimb
Manus
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  • Distal carpal 5
Pelvic girdle
Hindlimb
Pes
Tarsus
Proximal tarsals
Centralia
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Distal tarsals
Composite tarsals
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  • Navicular (Centrale 1+2)
  • Cuboid (Distal tarsal 4+5)
Miscellaneous
  • Parentheses denote bones that receive a different name in particular clades
  • Italics denote neomorphic bones present only in particular clades


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