Evolution of the mammalian middle ear

  title={Evolution of the mammalian middle ear},
  author={Edgar F. Allin},
  journal={Journal of Morphology},
  • E. Allin
  • Published 1 December 1975
  • Biology
  • Journal of Morphology
The structure and evolution of the mandible, suspensorium, and stapes of mammal‐like reptiles and early mammals are examined in an attempt to determine how, why, and when in phylogeny the precursors of the mammalian tympanic bone, malleus, and incus (postdentary jaw elements and quadrate) came to function in the reception of air‐borne sound. The following conclusions are reached. 

Eotherapsid hypothesis for the origin of Monotremata

Comparative study of the cranial structures of mammals and theromorphs shows that Monotremata evolved from the eotherapsid stem of theROMorphs, while therian mammals are descendants of eutherapsids.

Comment on "Independent Origins of Middle Ear Bones in Monotremes and Therians" (I)

The middle ear ossicles of all extant, adult members of crown-group Mammalia are homologous with a series of bones in the lower jaw of nonmammalian amniotes, suggesting that the structurally complex mammalian ear evolved independently.

Non-Mammalian Synapsids: The Beginning of the Mammal Line

The anatomy of the middle ear region of the known sequence of fossil stem-group mammals—pelycosaurs, basal therapsids, and several cynodonts—is reviewed in this chapter and the interpretation offers support for the second view.

Coevolution of the Mammalian Middle Ear and Neocortex

Phylogenetic analysis with x-ray computed tomography of fossilized and recent crania implicates differential growth of the neocortex in the evolution and development of the mammalian middle ear. In

Morphological evolution of the mammalian jaw adductor complex

The evolution of the mammalian jaw during the transition from non‐mammalian synapsids to crown mammals is thought to have allowed the evolution of a more‐efficient masticatory system in comparison to the plesiomorphic synapsid condition.

Monotreme middle ear is not primitive for Mammalia

Concerns are raised about terminology and identification of the incus presented by Wang et al. and show that their analysis does not support their hypothesis that a middle ear with a monotreme-like incus and malleus and incudomallear articulation was primitive for mammals.

Evolution of the Middle and Inner Ears of Mammaliaforms: The Approach to Mammals

The homoplasies of ear structures in early mammalian evolution, although seemingly complex, are consistent with the new understanding of a labile morphogenesis of mammalian ears under a complex developmental genetic network.

The evolution of the mammalian pharynx

The hypothesis of neuromuscular conservativism in the evolution of the mammalian feeding mechanism is considered and it is concluded that few data exist to support this hypothesis.

Evolution of the mammalian middle ear: a historical review

The present review emphasizes the problem of how the mammalian middle ear structures that developed at the angle of the lower jaw were transferred to the basicranium; the ontogenesis of extant marsupials provides important information on this question.



The Mammalian Middle Ear

Several implications of new work on the anatomy of the middle ear region of mammal-like reptiles were discussed and it was suggested that the primitive reptilian-tympanic cavity was supplemented by a recessus mandibularis related to the region of the notched angular bone.


The course of early evolution of the tetrapod middle ear is interpreted in the light of function and support of the tympanum in the pelycosaurs.

The hyomandibular of Eusthenopteron and the tetrapod middle ear

  • T. S. Westoll
  • Medicine
    Proceedings of the Royal Society of London. Series B - Biological Sciences
  • 1943
It is considered that Eaton’s theory of the transformation of the Rhipidistian hyomandibular to the primitive tetrapod ‘stapes’ or columella is essentially correct.

Dentary-Squamosal Joint and the Origin of Mammals

The dentary-squamosal jaw joint evolved more than once in advanced cynodont therapsids or their descendants, probably as a buttress against the reaction force created at the articulation by the


  • G. Manley
  • Biology
    Evolution; international journal of organic evolution
  • 1972
The functional significance of changes in the middle ear transmission system is discussed, particularly in connection with the origin of the mammalian middle ear, the development of large inner ear potentials and dimensionalChanges in the inner ear.


It is demonstrated that the position of the nerve in the pelycosaurs represents a logical intermediate between the condition of fish and amphibians on one hand and all amniotes on the other, and to show that changes of the middle ear from fish to modern amniots can reasonably be documented by known fossil forms.

New Light on the Mammalian Ear Ossicles

The structure of the middle ear region of several therapsids is greatly illuminated by this work; but some of his conclusions seem to be open to question, while others can be further supported.

The jaw articulation of the Docodonta and the classification of Mesozoic mammals

  • K. KermackFrances Mussett
  • Biology, Environmental Science
    Proceedings of the Royal Society of London. Series B - Biological Sciences
  • 1958
Comparison with the most advanced of the mammal-like reptiles shows that this groove must have been for the malleus (articular), which in Docodon and in Morganucodon still functioned as part of the jaw articulation, although in both the main part of this hinge would have been formed by the well-developed mammalian condyle on the back end of the dentary.

II.—On the Cynodont genus Galesaurus, with a note on the functional significance of the changes in the evolution of the Theriodont skull

(1934). II.—On the Cynodont genus Galesaurus, with a note on the functional significance of the changes in the evolution of the Theriodont skull. Annals and Magazine of Natural History: Vol. 13, No.

On the Structure of the Skull in the Mammal-Like Reptiles of the Suborder Therocephalia

The first-known mammal-like reptiles were discovered by Andrew Geddes Bain (1845) in the Karroo Beds of South Africa about a hundred years ago. The large majority of the species he discovered belong