External and middle ear characteristics of primates, with reference to tarsier-anthropoid affinities. American Museum novitates ; no. 2787

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New York, N.Y. : American Museum of Natural History
"Otic anatomy has been used to propose two different hypotheses about tarsier-anthropoid affinities: (1) Tarsius and Anthropoidea evolved independently from Paleogene omomyid tarsioids, and (2) Tarsius (or Tarsiidae) and Anthropoidea are phyletic sister groups. The arrangement of otic structures into form-function complexes of the middle and external ear is essential for phylogenetic analysis. Although the middle ear cavities in anthropoids contain mastoid cells not present in Tarsius, the two taxa share tympanic and anterior accessory cavities in a dual cavity-septum configuration. The resonant effects of the two coupled volumes are closely similar in Saimiri and Tarsius despite marked differences in the position of the septum and aditus, suggesting that their middle ear morphology is convergent. Although the intrapetrosal pathway of the internal carotid artery has been described as 'perbullar' in both anthropoids and Tarsius, the artery crosses part of the tympanic cavity (promontory) in platyrrhines but not in Tarsius. Furthermore, a branch of the tympanic nerve passes through the carotid foramen in at least some anthropoids but not the anterolaterally-shifted carotid foramen of Tarsius. The emergence of the internal carotid nerve onto the external aspect of the promontorial canal in tupaiids and probably Rooneyia viejaensis supports Szalay's (1975a) contention that a large promontorial artery links omomyids with living haplorhines. The bony external meatal tube is an adaptation designed to reduce physiological noise in species where the jaw joint borders directly on the external ear. Since the bony meatal tube is characteristic of the rounded and clinocranial skull of Tarsius, the skull of the earliest anthropoids probably did not closely resemble those of Tarsius or Paleogene forms currently recognized as 'tarsioid'"--P. [1].
23 p. : ill. ; 26 cm.
Includes bibliographical references (p. 21-23).