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Re: dino-lice



On Thu, Apr 21st, 2011 at 8:23 AM, Jason Brougham <jaseb@amnh.org> wrote:

> Here you suggest that a bare neck and head might correlate with scavenging.
> 
> I am skeptical of that idea. I've heard it before in paleo circles but I
> have a few questions.
> 
> First, cassowaries, turkeys, and wood storks all have bare heads and necks
> and none are scavengers. Has anyone demonstrated a correlation between
> bare - headedness and scavenging?

It seems to be a one-way relationship. Amongst scavenging birds that regularly 
plunge their heads 
into unmentionably nasty places, bare heads and necks are a distinct advantage 
(old-world and 
new-world vultures, Leptoptilos storks). However not all birds with featherless 
heads/necks are 
scavengers.

> Second I wonder about the functional inference. Why don't coyotes, skunks,
> wolverines, hyenas, and tasmanian devils suffer from fouling of their face
> and neck fur? Why don't ravens and caracaras?

Animals that live in social groups have the option of grooming each other 
afterwards, with the 
mammalian tongue seemingly better suited to the task than the avian tongue. 
Many of the species 
you mention also tend not to spend quite as much time up to their shoulders in 
hippo anuses as 
naked-necked vultures and storks do.

> Last, in Shuvuuia and Mononykus, don't the myriad tiny teeth that lack
> individual sockets, and which are set together in an alveolar groove, look
> different from what we'd expect in a scavenger?

Mammalian scavengers often utilise bone, due to our marvelously robust and 
adaptable teeth and 
jaws. Avian and reptilian scavengers tend to avoid crunching into bone, due to 
their 
crappy 'primitive' homodont teeth. Tyrannosaurs might have pulled it off, but 
theirs was a brute-
force and sheer-size approach to the problem, rather than the more subtle 
heterodont adaptations 
us mammals are capable of.

If you are targetting putrid flesh then you don't need much in the way of teeth 
anyway. Neither are 
teeth all that necessary if you swallow small things whole.

-- 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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