Abdominal muscle and epipubic bone function during locomotion in Australian possums: Insights to basal mammalian conditions and eutherian-like tendencies in Trichosurus

Reilly, Stephen M., McElroy, Eric J., White, Thomas D., Biknevicius, Audrone R. and Bennett, Michael B. (2010) Abdominal muscle and epipubic bone function during locomotion in Australian possums: Insights to basal mammalian conditions and eutherian-like tendencies in Trichosurus. Journal of Morphology, 271 4: 438-450.


Author Reilly, Stephen M.
McElroy, Eric J.
White, Thomas D.
Biknevicius, Audrone R.
Bennett, Michael B.
Title Abdominal muscle and epipubic bone function during locomotion in Australian possums: Insights to basal mammalian conditions and eutherian-like tendencies in Trichosurus
Formatted title Abdominal muscle and epipubic bone function during locomotion in Australian possums: Insights to basal mammalian conditions and eutherian-like tendencies in Trichosurus
Journal name Journal of Morphology  (ERA 2012 Listed)    (ERA 2010 Rank C)   Check publisher's open access policy
Publication date 2010-04
Sub-type Article
Year available 2009
DOI 10.1002/jmor.10808
Volume number 271
Issue number 4
ISSN 0362-2525; 1097-4687
Start page 438
End page 450
Total pages 13
Place of publication Hoboken, NJ, United States
Publisher John Wiley & Sons
Collection year 2010
Language eng
eng
Abstract Mammals have four hypaxial muscle layers that wrap around the abdomen between the pelvis, ribcage, and spine. However, the marsupials have epipubic bones extending anteriorly into the ventral hypaxial layers with two additional muscles extending to the ventral midline and femur. Comparisons of South American marsupials to basal eutherians have shown that all of the abdominal hypaxials are active bilaterally in resting ventilation. However, during locomotion marsupials employ an asymmetrical pattern of activity as the hypaxial muscles form a crosscouplet linkage that uses the epipubic bone as a lever to provide long-axis support of the body between diagonal limb couplets during each step. In basal eutherians, this system shifts off the femur and epipubic bones (which are lost) resulting in a shoulder to pelvis linkage associated with shifts in both the positions and activity patterns of the pectineus and rectus abdominis muscles during locomotion. In this study, we present data on hypaxial function in two species (Pseudocheirus peregrinus and Trichosurus vulpecula) representing the two major radiations of possums in Australia: the Pseudocheiridae (within the Petauroidea) and the Phalangeridae. Patterns of gait, motor activity, and morphology in these two Australian species were compared with previous work to examine the generality of 1) the crosscouplet lever system as the basal condition for the Marsupialia and 2) several traits hypothesized to be common to all mammals (hypaxial tonus during resting ventilation, ventilation to step synchrony during locomotion, and bilateral transversus abdominis activity during locomotor expiration). Our results validate the presence of the crosscouplet pattern and basic epipubic bone lever system in Australian possums and confirm the generality of basal mammalian patterns. However, several novelties discovered in Trichosurus, reveal that it exhibits an evolutionary transition to intermediate eutherian-like morphological and motor patterns paralleling many other unique features of this species. J. Morphol., 2010. © 2009 Wiley-Liss, Inc.
Keyword Locomtion
Marsupial
Mammals
Hypaxial
Eutherian
Epipubic bone
Mammal evolution
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article first published online: 27 OCT 2009

Document type: Journal Article
Sub-type: Article
Collections: 2010 Higher Education Research Data Collection
School of Biomedical Sciences Publications
 
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