Re: feather tracts (and spiny tails?)

["Jaime A. Headden" <qilongia@yahoo.com>]

Ken Kinman (kinman@hotmail.com) wrote:

<As I said before, better to be a theropod with a balancing
problem than a dead theropod.>

  Heh ... a theropod with a balancing problem is a dead
theropod.
It;s not like a quadruped who can walk on three legs if need be.
If a theropod was tripping over, or couldn't run properly, or
escape fast enough, then it's not likely to survive really well.
Thus, pressure NOT to have such a tail adaptation, irrelevant of
how glass snakes and *Uromastix* can do this, as they either hug
the ground, or are quadrupedal, and do not require the tail to
keep them from toppling over.

<The small forms which developed early protofeathers wouldn't
necessarily have been obligate bipeds in the first place, and
even if they were, the animal could often compensate enough to
get by if the section of tail lost wasn't too massive.>

  Based on what evidence? This is speculationb rampant to
suggest that there were feathered quadrupedal dinosaurs before
there were bipedal animals. This has been discussed _to death_,
and whole herds of dead horses have been whipped.

<Since the vast majority of the mass is in the proximal part of
the tail, the loss of 20 or 30% of the distal tail length would
not be a huge loss in mass (5-10% or less, maybe a lot less if
the animal tail was long and skinny distally, but still "meaty"
proximally).>

  Okay, make a mechanical model to support how loosing 5-10% of
the tail will make an animal like *Velociraptor* or *Oviraptor*
_not_ topple over. The shortening of the tail is always
correlated with a shift in the form of the hip and mass between
the knees, so any abrupt shortening of the tail _will_ be
demonstrable.

<And finally, why would they have to necessarily be herbivores,
as opposed to insectivores or even meat-eaters.>

  Insectivores (possibly, troodontids) tend to have effective
defense strategies in the form of large claws, sickle-claws on
the feet, great capability for speed, etc.; *Microraptor* may be
another insectivore with arboreal capabilities, thus staying
away from the likely predators (only true birds now may be
effective competition). We're not talking mammals here. Other
carnivores are evenly defensive, or smaller and swifter, and
have various other means of evasion. Only the larger, slower
animals would need a defense strategy for one on one encounters
with an animal that could kill it. Herbivores either develop
armor, great size, speed, small size, social groups, or unique
defences to retard predator effectiveness. Only hadrosaurs seem
to be utterly without anatomical defenses, but have the social
group which may have been year-round.

<There is no rule that a bigger meat-eater can't pursue smaller
meat-eaters.>

  No, there's not, and I was replying to this assumption. The
statement here is that the only known "fuzzy" theropods are all
possible small carnivores or larger herbivores, omnivores,
insectivores. The majority have no indication that any form of
integument was quilly (see *Sinornithosaurus,* *Microraptor,*
*Beipiaosaurus*) or that there were feathers on the tail
(*Caudipteryx,* *Protarchaopteryx,* birds) that suggest if
quills were anywhere along the line, it was ill-supported
sideline. We need more data to support the theory.

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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