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RE: Brooding rex? (was Feathers for T. rex)
Tom Holtz wrote:
>IF Galloanserae is monophyletic and near the base of Neognathae, the
>larger clutch size in grouse, ducks, pheasants, etc. may be
>symplesiomorphy rather than ecomorphology (or rather eco-behavior). >That
is, the smaller clutch size of owls, falconiforms (and sea birds >and
hummers and what have you) relative to galliforms and anseriforms >MIGHT be
a synapomorphy of dervied neognaths.
In a similar vein, I've wondered if other traits seen in certain
galloanserine species (such as the uniform distribution of contour feathers
over the body [rather than organization into tracts]; and the presence of
down/plumules between the contour feathers) may be primitive neognath
>Furthermore, I have no idea of the clutch size of tinamous, which might >be
useful to know!
>From memory, quite large - up to 12-18 eggs.
Ken Kinman wrote:
> Should probably be more careful what you aim your torpedoes at.
No, I think this particular torpedo was on target. Any collateral damage
>I'm not saying there are any hard and fast rules.
> However, raptorial birds like hawks, eagles, and owls, usually have
>clutches of 2-4 eggs. Many common prey species (like grouse, ducks,
>pheasants, etc.) have larger clutches more like 5-15 eggs (or more). I
>see no reason that trends among early coelurosaurs (predators vs. prey)
>would have been much different (but again there would be exceptions to
True, there are no "hard-and-fast" rules. There are ecological
considerations to account for too - nesting on the ground vs nesting in
trees; availability of food; etc.
(An interesting fact: For some raptorial birds, the first chick to hatch
actually eats its younger siblings. An analogous process happens in some
shark species, where an embryo shark will eat its siblings *in utero*.)
The fact is, for dinosaurs (of the non-avian kind), we really don't know
enough to draw *any* inferences regarding cluch size in different theropod
>P.S. I actually live close to a farm, and chickens seem to be prolific
>egg layers (not that I am going to base any biological hypotheses on >farm
Good idea. Modern battery hens are bred for proficiency in egg production.
Their selection has been decoupled from any natural processes.
Timothy J. Williams
Iowa State University
Ames IA 50014
Phone: 515 294 9233
Fax: 515 294 3163
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