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Harris' Hawks and Cheetahs

Some comments on "pack hunting" and the only "good" evidence of it in the
dinosaurian world:

  1) Harris' hawks do not pack hunt. They hunt cooperatively, and
ecologists have a strict definition remarking the two: pack hunting, as in
wolves, required multiple partners working in tandem to cripple, bring
down, steer, or ambush and chase prey. You see this with Cape hunting dogs
and even hyenas on occassion. In lions, typically there will be three
lionesses, one in plain view and the others sneaking around, in an effort
to distract and surround a likely target. Cooperative hunting requires one
or two more animals to take down a target, or harrass and harry, but one
animal makes the kill, but each animal is in it for themselves. Sometimes
playing the numbers game increase chances of taking down a target. After
that, it's all for one.

  2) Cheetahs do not pack hunt. They, like hawks, will cooperatively take
down prey on occasion, especially if labored or inexperiences. A mother
cheetah with new cubs and earlier, two year offspring on the Serengeti
will occassionally team up to take down a gazelle ... she is just too
tired to do this on her own, the older cub will get easier food this way.
Two siblings will pair up in their first few years for largely the same
reason, and they share, but once they get a few kills under their
haunches, the share game ends. Cats are funny hunters. The mother takjes
the first nibbles, and after she's had hers, everyone else can get theirs.

  3) There is no proof *Deinonychus* ever hunted in packs. Pack hunting
does not fossilize, and the association of teeth with *Tenontosaurus*
remains does not prove anything other than feeding on carcasses, not the
manner in which the animal died. Maxwell and Ostrom reported on the find
of at least three *Deinonychus* animals (as determined by broken distal
halve of three tails) around one side of a partial *Tenontosaurus*
skeleton, in a fluviatile bedding plane. First warning is the environment,
second the disarticulated predator remains. One can draw at least two
scenarios using the data at hand, and one involves more data than the
others: a) the *Tenontosaurus* carcass was washed some distance where it
ended up on a bank somewhere and was subsequently fed upon (only evidence
of shed dromie teeth indicates feeding, and this could be tricky; they may
be dislodged or washed from elsewhere --- possible, but unlikely); or b)
both tenonto and dromies were washed in a single flash event, or the
dromies were subsequently washed in, but this would not explain the
accumulation of the teeth. Marks on bone as is found in several herbivores
of the Hell Creek fauna similarly do not indicate pack hunting, and
Currie's gregarious tyrannosaur model is only that, a gregarious model,
which he then applied an admittedly tenuous concept of juvenile--adult
two-pronged--attack strike force.

  There is no evidence that any dinosaur ever pack hunted, or even
cooperatively hunted. Brain size won't tell you, anatomy won't tell you,
and extant behavior won't tell you anything about something dead; fossil
accumulations might tell you how it died, but pack hunting generally
requires a chase, and tracks so far show only where a single large
theropod did a hop-skip after a sauropod in the Paluxy River Valley of
Texas some 100 odd mya. That in extant ecologies only communal, "priding"
or flocking animals feed on the same carcass at any one time, without
other animals interfering (one kind of vulture at one, lions, no jackals
or hyenas until the others have gone or been chased off, etc.) suggests
there may have been some communal structure in *Deinonychus* and this is
indeed what Currie suggests on his find of "communal" *Albertosaurus*. And
that, folks, is about all we can get out of the bones.

  And who said taphonomy isn't fun?


Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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