Morphological variation in the ear region of pleistocene elephantimorpha (Mammalia, Proboscidea) from central Texas
Article first published online: 31 JAN 2011
Copyright © 2011 Wiley-Liss, Inc.
Journal of Morphology
Volume 272, Issue 4, pages 452–464, April 2011
How to Cite
Ekdale, E. G. (2011), Morphological variation in the ear region of pleistocene elephantimorpha (Mammalia, Proboscidea) from central Texas. J. Morphol., 272: 452–464. doi: 10.1002/jmor.10924
- Issue published online: 10 MAR 2011
- Article first published online: 31 JAN 2011
- Manuscript Accepted: 30 SEP 2010
- Manuscript Revised: 1 SEP 2010
- Manuscript Received: 24 JUN 2010
- National Science Foundation. Grant Number: NSF EAR-0345710
A large sample of isolated elephantimorph petrosal bones was recovered from Pleistocene deposits in Friesenhahn Cave, Bexar County, Texas. Morphology of the middle and inner ear of the elephantimorphs is described and variation within the sample is identified. Observed variations occur in the stapedial ratio, morphology of the aquaeductus Fallopii, and connection of the crista interfenestralis to the tympanohyal on the posterior portion of the petrosal to form a foramen for passage of the stapedius muscle. The morphology of the aquaeductus Fallopii supports an ontogenetic explanation for some variation, and a sequence of ossification surrounding the aquaeductus Fallopii, from the anterior end of the canal to the posterior, is hypothesized. The stapedial ratio varies to a high degree across the sample, and such variation should be considered when the ratio is used in phylogenetic analyses. Within the inner ear, the absence of the secondary lamina suggests evolution of low-frequency hearing in extinct proboscideans, which is known for extant elephants. The morphology of the petrosals from Friesenhahn Cave is compared to published descriptions of the ear regions of other extinct proboscideans, and the distribution and evolution of morphologic characters are discussed. J. Morphol., 2011. © 2011 Wiley-Liss, Inc.