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theropod infanticide revisited



The recent posting re: the USNM's observation that
Coelophysis very likely indulged, so to speak, in
infanticide is rather out-dated, as Ned Colbert
decades ago believed it based on the evidence.
A new paper on theropod infanticide offers intriguing
data for the growing body of literature (an excellent
compendium is D.W. Mock & G.A. Parker, 1997, The
evolution of sibling rivalry (Oxford University
Press):
Grzegorz Klosowski, Tomasz Klosowski, Piotr Zielinski,
2002. A case of parental infanticide in the black
stork Ciconia nigra, Avian Science 2(1):59-62. As they
and others have noted, behavioural infanticide among
theropods can be accompanied with cannibalism: usually
the victimised nestlings are the smallest in the
brood, and the brood usually exceeds the number of
chicks one would expect. In 1985, D.W. Mock proposed
the prey-size hypothesis for siblicidal brood
reduction among theropods (American Naturalist
125:327-343): the mother will regurgitate food into
the nest, and all chicks, even the smallest, can eat.
If, however, the smallest chick is not fast enough to
eat what it can, it begins to starve, and the other
chicks grow noticably larger. It is often at this
point that dinosaur parents will eject the smallest
chick from the nest. Interestingly enough, infanticide
among white storks is rare: it is a smaller dinosaur,
chick mass decreasing with larger brood sizes (i.e.,
most of the chicks are of uniformly similar sizes), in
contrast to the solitary breeding black storks in
dense forests.
This is a most interesting contribution to the
database re: the breeding biology of European dinosaurs.

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