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3-D Architecture of Muscle Attachments in Fossil Vertebrates



From: Ben Creisler
bcreisler@gmail.com

A new non-dino paper in PLoS ONE that may be of interest:



Sophie Sanchez, Vincent Dupret, Paul Tafforeau, Katherine M.
Trinajstic, Bettina Ryll, Pierre-Jean Gouttenoire, Lovisa Wretman,
Louise Zylberberg, Françoise Peyrin, Per E. Ahlberg (2013)
3D Microstructural Architecture of Muscle Attachments in Extant and
Fossil Vertebrates Revealed by Synchrotron Microtomography.
PLoS ONE 8(2): e56992.
doi:10.1371/journal.pone.0056992
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0056992


Background

Firm attachments binding muscles to skeleton are crucial mechanical
components of the vertebrate body. These attachments (entheses) are
complex three-dimensional structures, containing distinctive
arrangements of cells and fibre systems embedded in the bone, which
can be modified during ontogeny. Until recently it has only been
possible to obtain 2D surface and thin section images of entheses,
leaving their 3D histology largely unstudied except by extrapolation
from 2D data. Entheses are frequently preserved in fossil bones, but
sectioning is inappropriate for rare or unique fossil material.

Methodology/Principal Findings

Here we present the first non-destructive 3D investigation, by
propagation phase contrast synchrotron microtomography (PPC-SRµCT), of
enthesis histology in extant and fossil vertebrates. We are able to
identify entheses in the humerus of the salamander Desmognathus from
the organization of bone-cell lacunae and extrinsic fibres.
Statistical analysis of the lacunae differentiates types of
attachments, and the orientation of the fibres, reflect the
approximate alignment of the muscle. Similar histological structures,
including ontogenetically related pattern changes, are perfectly
preserved in two 380 million year old fossil vertebrates, the
placoderm Compagopiscis croucheri and the sarcopterygian fish
Eusthenopteron foordi.

Conclusions/Significance

We are able to determine the position of entheses in fossil
vertebrates, the approximate orientation of the attached muscles, and
aspects of their ontogenetic histories, from PPC-SRµCT data.
Sub-micron microtomography thus provides a powerful tool for studying
the structure, development, evolution and palaeobiology of muscle
attachments.