Re: Bone density in mustelids

Marc Verhaegen <m_verhaegen@xxxxxxxxx> wrote in
news:C379AF66.9EFE%m_verhaegen@xxxxxxxxx:




Op 03-12-2007 03:34, in artikel
65242200-57e1-4fcc-91a0-e740aa97b3ff@xxxxxxxxxxxxxxxxxxxxxxxxxxxx, Lee
Olsen <paleocity@xxxxxxxxxxx> schreef:

On Dec 2, 4:36 pm, Marc Verhaegen <m_verhae...@xxxxxxxxx> wrote:
FE Fish & BR Stein 1991 Zoomorphol.110:339-345
Functional correlates of differences in bone density among
terrestrial and aquatic genera in the family Mustelidae (Mammalia)

"the costs of maintaining an increased skeletal mass increases
according to locomotor function as follows : swimmers, sedentary
forms, slow runners, fast runners, and flyers"
No reason why erectus must be an exception, IOW, the H.erectus
endurance running hypothesis is pure nonsense.

Of course the fallacy in wet ape thinking is that Homo e has to run
as fast as a today's
marathon runners to catch a kudu, when in fact one does not. Nor
does
one have to
run fast to catch a tortoise.

So?? And??

My little boy, H.erectus has pachyostosis,

"In some specimens [of tapinocephalian] this boss is of only moderate
thickness, while in others it has become greatly thickened into a huge mass
of bone (pachyostosis). It has been suggested that these animals engaged in
intra-specific head-butting behaviour (left), presumably for territory or
mates. A similar thickening of the skull occurs in pachycephalosaur
("boneheaded") dinosaurs, and it is speculated that all these animals
practised head-butting behaviour like modern goats and bighorn sheep, and
late Eocene Titanotheres."
http://www.kheper.net/evolution/therapsida/Tapinocephalidae.htm

osteosclerosis

"Most of the sabertoothed cat vertebral specimens we studied exhibited
diffuse osteosclerosis on both conventional radiographs and CT images."
www.ajronline.org/cgi/reprint/148/4/779.pdf

, medullary
stenosis

As medullary stenosis is properly a pathological condition compared to the
general population, I presume that what you mean is that H.erectus *as a
population* has greater cortical thickness and reduced medullary cavity.
Two problems:

1. To which other population are you comparing H.erectus?

2. Increased cortical thickness and decreased medullary volume don't seem
to mean what you think they mean:

"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:

"SWIM[swimmers] and CYC[cyclists] had significantly larger (P < 0.05) size-
adjusted medullary cavity CSA than RUN[runners] and TRI[triathletes]"
(ibid)

So while you may be correct that H.erectus medullar cavity size is smaller
(than what?) the pattern appears to show that this would mean H.erectus
spent *more* time walking and running, not less.

- all these are *only* found in slow divers.

Apparently you are incorrect.

Unless you can explain these, keep your big mouth shut.

Unless you can explain why counterexamples to your "absolute" evidence
don't count, perhaps you should take your own advice?

[snip]

--
Bon nou mujin sei gan dan
.

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