Re: Fwd: RE: T. rex Predation

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

Tim Donovan (uwrk@yahoo.com) wrote:

<I suspect even big dromies attacked sauropods-note that Achillobator co
occurs with a sauropod at Burkhant, and there were sauropods in the
Utahraptor environment.>

  *Achillobator* is no bigger than *Deinonychus*, it is no super
dromaeosaurid. The sauropod is uncorroborated, and undescribed.
*Deinonychus* co-occurs with some titanosaur and brachiosaur material,
such as a possible specimen of *Sauroposeidon*, but one would think a
wolf-sized animal would have trouble taking down a three-times
elephant-sized animal. 

<The Amargasaurus spines probably reflect a theropod preference for
sriking the neck, although there were other ways to protect it->

  Like having the spines project radially from the sagittal plane, which
theyt do not. This is the case with such obvious protective armor as in
ankylosaurians, but in *Amergasaurus* the spines are straight and
vertical, and very slender and would likely have suffered considerable
damage if used defensively.

<the stiffened tails of titanosaurs>

  Pray what? 

<may have evolved in part to keep the neck elevated out of reach for the
duration of an attack, as the titanosaur assumed a tripodal stance.>

  This would best be explained by a flexible tail, not a rigid one. The
tail must be flexible. Similarly, no one has been able to examine the
possible stresses and mechanics behind tail use in "tripoding" in
sauropods and how one would actually be able to support it using only a
tail.

<Sauropod survival strategies undoutedly influenced theropod evolution.
Why did Acrocanthosaurus have a stronger bite than Jurassic theropods?>

  The stronger lower jaw of *Acrocanthosaurus* only involves the power of
the bit itself ... This says nothing much for the effect of the jaw on the
prey item, but rather effectiveness in processing flesh. In *Carnotaurus*
and *Allosaurus*, the head was hatchet-like in the upper skull having a
weaker jaw (relatively) and a strong head-neck system with reinforced
upper jaw used to ram down onto something. Bakker describes this well in
his GAIA 15 paper, as in the *Carnotaurus* paper.

<Were stronger jaws selected for because EK sauropods often fled whereas
bigger Jurassic ones stood their ground?>

  We are forgetting strong-jawed *Ceratosaurus*. And the plentitude of
Morrison sauropods throughout all members and time.

<I suspect Abelisaurs attacked juvenile titanosaurs in which armor wasn't
yet expressed.>

  At least one abelisaurid used the head-hatchet method of engaging prey,
as did *Allosaurus*. *Abelisaurus* is suspect for having a longer snout
with small teeth, but *Majungatholus* has a skull proportioned and shaped
more similar to *Carnotaurus*, and may have used this method as well.
Abelisaurids have large epipophyses on their cervicals which wouild have
served to strengthen the epaxial deflexing (straigtening) tendons of the
neck.

  Cheers,

=====
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.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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