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RESEARCH INTERESTS
Functional and evolutionary vertebrate morphology; biomechanics
Locomotor - respiratory integration in mammals
Cursorial specialization and hominid evolution
Functional morphology and evolution of lower tetrapods
PUBLICATIONS
Locomotor Respiratory Integration in
Mammals
Physiologically, mammals (and birds) are distinguished
by their capacity for sustained aerobic exercise, often in
the context of endurance locomotion (i.e., running, flying,
etc.). Lower tetrapods (amphibians and reptiles) are
incapable of such behavior and much of the reason for
this may rest with their inability to successfully
integrate locomotion and respiration. The effective
coupling of these two mechanical functions, and hence
the ability to run and breathe simultaneously, appears to
be an evolutionarily derived condition of major
importance to the emergence of mammalian locomotor
energetics, behavior and ecology.
Our primary research interest is the functional
morphology of mammalian locomotor-respiratory
interactions, their physiological consequences and,
ultimately, a better understanding of their evolutionary
history. We are currently using a variety of experimental
techniques (in collaboration with Prof. F.A. Jenkins, Jr. of
Harvard University) to document the patterns of
interaction between gait and breathing cycles and to
clarify their biomechanical bases. These approaches
include synchronized high speed light and
cineradiographic filming of running mammals combined
with pneumotachographic recording of respiratory
flow.
Cursorial Specialization and Hominid
Evolution
A more recent interest concerns human locomotory
mechanics and their historical importance. Although
humans are not usually considered to be cursorial (i.e.,
specialized for running) it can nonetheless be shown that
when gait dependent factors are taken into account the
locomotor performance of modern elite distance runners
equals or exceeds that of many cursorial quadrupedal
mammals of equal body size. Additionally, numerous
structural peculiarities of the human body plan seem to
be most plausibly interpreted as modifications for
endurance running. These include (but are not limited to)
lower limb and pelvic proportions, tendonization of the
crural musculature, details of cranial configuration and
the mechanisms of head-neck stabilization during
running. These and other features seem to characterize
the genus Homo and to set it sharply apart from all
other hominoids, including the ancestral
australopithecines. We are utilizing experimentally
derived data from modern human gait analyses together
with biomechnial modeling and comparative morphologic
information obtained from Recent and fossil hominoids
to test the hypothesis that selection for running ability
has had a significant role in human history.
Functional Morphology and Evolution for Lower
Tetrapods
I have a long-standing interest in the structure, function,
and evolution of turtles with an emphasis on the
constructional design of the shell. Previous published
studies have analyzed the biomechanics. Evolution and
systematic implications of shell kinesis within the
testudinate families Emydidate, Kinosternidae and
Pelomedusidae. A similar investigation of shell design
and evolution in soft-shelled turtles and their allies
(Trinonychoidea) is nearing completion. I also have a
continuing research interest in problems associated with
the functional and ecological morphology of lower
tetrapod feeding complexes.
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