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Re: Max Size w/ Feathers

> Jaime Headden <jaemei@hotmail.com> writes:
>   I want to know the maximum mass and size attainable with a 
> fully-feathered body. I think that ostriches may have reduced their 
> feathered covering for this reason, in order not to overheat, so I would 
> like comments on that, too.

For starters, I understand that emus actually use their feathers to protect
themselves from the direct sunlight of Australia.  Insulation works both
ways, you see.

To answer your question fully, someone needs to address the integument of
the extinct elephant bird of Madagascar which, with a weight estimate of
about 420 kg (a bit under 1,000 pounds) according to Paul's _PDW_, would
have been the most massive bird known.

But the next most massive bird known, the 270 kg _Dinornis giganteus, the
largest of the extinct moa species of New Zealand, (estimated at 400 kg in
_PDW_) is certainly more massive than the extant ostrich (150 kg) and is
reconstructed with feathers extending the length of its tibiotarsus (down
to the ankle).  As feathers and skins of the recently extinguished moa are
available, I am assuming that the reconstructions are accurate in this
respect; correct me if I'm wrong.  The giant moa lived in the forest like
the cassowary does today, but the other ten recognized species of moa
established themselves in a wide variety of habitats.

For example, Megalapteryx didinus, an upland moa, weighed 15-20 kg and had
especially large feet.  This animal had scales only on its toes, for it
sported feathers all the way down the length of its tarsometatarsus, an
adaptation to a colder habitat.

I've pointed this out before, but contrary to the classic depiction, moa
could not have extended their necks vertically to the extent of ostriches. 
Their necks attached in a reptilian style to the foramen magnum at the
_back_ of the skull.  Consequently, they held their necks quite low, even
lower than cassowaries (relatively speaking).

It appears that the giant moa contradicts the notion that a fully feathered
body is impossible in an ostrich-sized animal.  Perhaps the ostrich needs
naked legs to enable the powerful leg muscles to shed heat when running
across the hot savannah.  Some moa were more massive than the ostrich, but
they were probably not nearly so athletic.

-- Ralph Miller III     gbabcock@best.com

Holdaway, Richard and Worthy, Trevor 1991.  _Lost in time_, New Zealand
Geographic, Number 12, October-December 1991, pp. 51-68.