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Avian pelvic limb bone scaling



From: Ben Creisler
bcreisler@gmail.com


Not strictly paleo, but a new article that might be of interest:

Doube, M., Yen, S. C. W., Kłosowski, M. M., Farke, A. A., Hutchinson,
J. R. and Shefelbine, S. J. (2012)
Whole-bone scaling of the avian pelvic limb.
Journal of Anatomy (advance online publication)
doi: 10.1111/j.1469-7580.2012.01514.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7580.2012.01514.x/abstract


Birds form the largest extant group of bipedal animals and occupy a
broad range of body masses, from grams to hundreds of kilograms.
Additionally, birds occupy distinct niches of locomotor behaviour,
from totally flightless strong runners such as the ratites (moa, kiwi,
ostrich) to birds that may walk, dabble on water or fly. We apply a
whole-bone approach to investigate allometric scaling trends in the
pelvic limb bones (femur, tibiotarsus, tarsometatarsus) from extant
and recently extinct birds of greatly different size, and compare
scaling between birds in four locomotor groups; flightless,
burst-flying, dabbling and flying. We also compare scaling of birds’
femoral cross-sectional properties to data previously collected from
cats. Scaling exponents were not significantly different between the
different locomotor style groups, but elevations of the scaling
relationships revealed that dabblers (ducks, geese, swans) have
particularly short and slender femora compared with other birds of
similar body mass. In common with cats, but less pronounced in birds,
the proximal and distal extrema of the bones scaled more strongly than
the diaphysis, and in larger birds the diaphysis occupied a smaller
proportion of bone length than in smaller birds. Cats and birds have
similar femoral cross-sectional area (CSA) for the same body mass, yet
birds’ bone material is located further from the bone’s long axis,
leading to higher second and polar moments of area and a greater
inferred resistance to bending and twisting. The discrepancy in the
relationship between outer diameter to CSA may underlie birds’
reputation for having ‘light’ bones.