Quantitative microanatomy of jaw muscle attachment in extant diapsids
Article first published online: 8 MAY 2006
Copyright © 2006 Wiley-Liss, Inc.
Journal of Morphology
Volume 267, Issue 8, pages 954–967, August 2006
How to Cite
Hieronymus, T. L. (2006), Quantitative microanatomy of jaw muscle attachment in extant diapsids. J. Morphol., 267: 954–967. doi: 10.1002/jmor.10450
- Issue published online: 5 JUL 2006
- Article first published online: 8 MAY 2006
- Charlotte and Walter Kohler Charitable Trust
- Mary Jane Davidson Student Fund
- Paleobiological Fund
- Gabriel Laboratory for Molecular and Cellular Paleontology
- muscle attachment;
- muscular reconstruction;
Muscular reconstructions in vertebrate paleontology have often relied heavily on the presence of “muscle scars” and similar osteological correlates of muscle attachment, a practice complicated by the fact that approximately half of tendinous muscle attachments to bone in extant vertebrates do not leave readily interpretable scars. Microanatomical and histological correlates of tendinous muscle attachment are much less ambiguous. This study examines the microanatomical correlates of muscle attachment for the mandibular adductors in six species of diapsids. Most prominent tendinous or aponeurotic muscle attachments display a high density of extrinsic fibers (similar to Sharpey's fibers). There is also some indication that the density of extrinsic fibers at an attachment may be directly related to the amount of stress exerted on that attachment. The presence of comparable densities of extrinsic fibers in fossil tissue constitutes strong and readily interpretable positive evidence for the presence of adjacent fibrous connective tissue in life. Microanatomy and histology provide reliable data about muscle attachments that cannot be gleaned from gross observation alone. These additional data, when coupled with existing muscular reconstruction techniques, may be essential to the resolution of ambiguous character states, and will provide more severe tests for long-standing hypotheses of musculature in extinct diapsids. Increasing the accuracy and precision of muscular reconstructions lends greater strength to any phylogenetic, paleobiological, or paleoecological inferences that draw upon these reconstructions as important lines of evidence. J. Morphol. © 2006 Wiley-Liss, Inc.