Marc Verhaegen
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 Posted: Wed Jul 30, 2008 5:39 am Post subject: savanna running nonsense |
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The increased density of the pakicetid skeleton would have left these early
cetaceans wholly unsuited to running, or even prolonged terrestriality, as
heavy skeletons are energetically expensive to move.(so obvious, but still
not well understood by savanna believers) In addition, the
hypermineralization (osteopetrosis) of pakicetid load bearing elements put
them at increased risk for fracture during terrestrial loading (de Vernejoul
and Bénichou, 2001), a risk that rises with velocity.(idem: dense bone is
more brittle) Thus, although they look superficially similar to their
cursorial relatives, it is likely that pakicetids made few sustained
terrestrial forays. The summed evidence of bone gross morphology and
microstructure indicates that pakicetid cetaceans were fully committed to an
aquatic lifestyle, and bore marked adaptations for bottom walking, paddling,
and undulatory swimming modes. |
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Lee Olsen
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| Posted: Wed Jul 30, 2008 5:39 am Post subject: Re: savanna running facts |
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Mujin wrote:
[quote][...]
"Conclusions: Running, a weight-bearing exercise, is associated with more
favorable geometric and biomechanical characteristics in relation to bone
strength, compared with the weight supported activities of swimming and
cycling. Differences may reflect skeletal adaptations to the specific
mechanical-loading patterns inherent in these sports"
http://www.acsm-msse.org/pt/re/msse/abstract.00005768-200204000-
00018.htm;jsessionid=HJxhg51XTP76vm2Q2tjGNy9JTQCZFcv3xHG8Qh2XL470Kzjk7kPB!-
1601909834!181195629!8091!-1
Clearly weight bearing, high impact activity increases cortical thickness
and decreases medullary cavity sizes. More importantly:
[/quote]
See also
http://www.ncbi.nlm.nih.gov/pubmed/10949001
Total and regional bone density in male runners, cyclists, and
controls.
Medicine & Science in Sports & Exercise. 32(8):1373-1377, August
2000.
...
Conclusion: Running is associated with increased bone density,
particularly in
the leg, whereas cycling is associated with a mild decrease in bone
density in
the spine. In athletes who do both, running exerts a stronger
influence than
cycling.
http://www.naturalhistorymag.com/master.html?http://www.naturalhistorymag.com/1206/1206_samplings.html
On Jul 29, 5:39 pm, Marc Verhaegen <m_verhae...@skynet.be> wrote:
[quote]The increased density of the pakicetid skeleton would have left these early
cetaceans wholly unsuited to running, or even prolonged terrestriality, as
heavy skeletons are energetically expensive to move.(so obvious, but still
not well understood by savanna believers) In addition, the
hypermineralization (osteopetrosis) of pakicetid load bearing elements put
them at increased risk for fracture during terrestrial loading (de Vernejoul
and Bénichou, 2001), a risk that rises with velocity.(idem: dense bone is
more brittle) Thus, although they look superficially similar to their
cursorial relatives, it is likely that pakicetids made few sustained
terrestrial forays. The summed evidence of bone gross morphology and
microstructure indicates that pakicetid cetaceans were fully committed to an
aquatic lifestyle, and bore marked adaptations for bottom walking, paddling,
and undulatory swimming modes.
[/quote]
This is from the same silly fool who thought mountain beavers were
semiaquatic.
No wonder all he do is publish OPINION papers. |
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