Journal of Mammalian Evolution

, Volume 23, Issue 4, pp 337–352 | Cite as

The inner ear of Protungulatum (Pan-Euungulata, Mammalia)

  • M. J. OrliacEmail author
  • M. A. O’Leary
Original Paper


We present new anatomical details about the bony labyrinth of Protungulatum based on micro CT-scan investigation of an isolated petrosal bone retrieved at the Puercan locality of Bug Creek Anthills and referred to Protungulatum sp. The exceptional state of preservation of the specimen allowed us to reconstruct the very fine details of the inside of the petrosal bone, including the bony labyrinth, the innervation of the vestibule and the innervation and vasculature of the cochlea. Estimation of the auditory capability of Protungulatum based on cochlear morphology indicate that Protungulatum was specialized for high-frequency hearing, with estimated low frequency limits above 1 KHz. Comparisons with Late Cretaceous non-placental eutherians and with early Tertiary pan-euungulates indicate that the bony labyrinth of Protungulatum is closer in general morphology to Mesozoic forms (low coiling and low aspect ratio of the cochlea, posterior orientation of the common crus, dorsal outpocketing of the cochlear fossula), and shares only a few characters with pan-euungulate and euungulate taxa. Interestingly, the bony labyrinth of Protungulatum also shares some morphological features with South American notoungulates and litopterns recently described from Itaboraí, Brazil. These new observations provide new morphological features of potential phylogenetic interest.


Bony labyrinth “Condylarthra” Vestibulocochlear nerve Spiral modiolar artery Placentalia Puercan Bug Creek 



For access to the micro CT-scanner we thank S. Judex and S. Xu of the Department of Biomedical Engineering, Stony Brook University, New York. We are also grateful to G. Billet for providing us with supplemental images of the bony labyrinth of the litoptern from Itaboraí and for his thorough review of the manuscript. This is ISE-M publication n° ISEM 2016-017. This research was supported by grants NSF-DEB 0629836, 9903964, NSF BDI-0743309, NSF-EAR 0622359 to M. A. O.

Supplementary material

10914_2016_9327_MOESM1_ESM.pdf (859 kb)
ESM 1 (PDF 859 kb)


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© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Institut des Sciences de l’Evolution, UMR 5554 CNRS, IRD, EPHEUniversité de MontpellierMontpellierFrance
  2. 2.Department of Anatomical Sciences, HSC-T-8 (040)Stony Brook UniversityStony BrookUSA

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