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Re: Coprophagy addendum
Stephan Pickering (StephanPickering@cs.com) wrote:
<The vultures -- an overlooked group of dinosaur "scavengers" (they often
kill their prey) -- are fascinating theropods, competing with mammalian
hyaenids (whose social group compositions are logical candidates for how
cohesiveness was maintained among dromaeosaur "packs").>
Though some vultures can kill, it should be noted that typically, many
of these are habitual and are falconiform. There are very few records of
the vulturid vultures being predaceous, though all typical scavengers can
and will kill. The ratio between killing and scavenging has not been fully
quantified in many scavengers.
Dromaeosaurid assemblages are restricted to fluviatile sediments in the
Cloverly and Antlers Formations of Montana and Oklahoma, and most of the
evidence comes from partial skeletons or several dozens of teeth of
*Deinonychus* around the remains of *Tenontosaurus*. No other
dromaeosaurid [see note below] has been found in association with another
of its species. This leaves interpretation of packs to *Deinonychus*,
which can also be explained as fluviatile transport, and so I do not think
the evidence is fairly concrete towards eusocial behavior. Conversely,
large predator traps in the Cleveland-Lloyd Quarry of the Morrison
Formation (near Price, Utah [where my uncle lives :) ]) have led to the
suggestion that *Allosaurus* may have formed predatory packs (not eusocial
groups) to take down sauropods. Packing behavior has also been suggested
by Currie in the GAIA 15 volume of last year for *Albertosaurus*, and
Larsson suggested it for *Tyrannosaurus*, but that evidence for the latter
may be more tenuous than for the former.
NOTE: *Dromaeosaurus*, *Saurornitholestes*, *Velociraptor*, and the French
material most likely -- other taxa are not truly dromaeosaurid, as the
taxon is restricted in usage [Currie, 1995] to the above or taxa closer to
any of the above than other taxa; this excludes many "dromaeosaurids" from
the taxon, including *Sinornithosaurus*, *Unenlagia*, and *Microraptor*.
*Bambiraptor* may or may not be a velociraptorine dromaeosaurid, as this
taxon too has some avialian qualities, but this may be transistory for a
birdy-to-terrestrial series as much as the reverse, and *Sinoventor*
appears to polarize phylogeny to the former.
Jaime A. Headden
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