Re: How would Tyrannosaurus approach a Triceratops?

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

John Hunt (john.bass@ntlworld.com) wrote:

<The evidence for T rex having some binocular vision comes from the cranial
remains that seem to suggest that the back of the skull was relatively broad
and the snout relatively narrow.  However, as skulls are normally crushed this
may be reconstruction bias.  Other large therapods appear to have broader
snouts.  Think croc vs. gator.>

  Actually, while this is partly true, the breadth of the rear of the skull is
only a corrollary to the relative condition in rex skulls, as in other
theropods. The reason that *T. rex* is said to have such binocular vision is
that the jugal, which is normally straight in ventral view in theropods, has a
particular kink in it in *T. rex* (and to a lesser degree in *T. baatar* and
*D. torosus*), which causes the orbit to face roughly 45 degrees to the
midline. Distortions of the skull and crushing (and thus widening) of the rear
of the skull can be used to explain a lot of things, but the shape and
articulation of the jugal, maxilla, quadrates, occiput, and further bones
indicate that reconstructions of the skull which are currently popular,
including those of Thomas Carr and Greg Paul, are correct in assuming this
skull is wide in the rear and narrower more anterior to the orbit.

<The evidence from CT scans of the braincase suggests the optic nerve was
substantial but the olfactory bulbs were enormous.  Some have interpreted this
to suggest the sight was not good, but this seems wrong to me - because the
sense of smell was extraordinary does not reduce the visual acuity.> This is at
the heart of the predator vs scavenger debate.  Seems to me that vast herds of
large herbivorous dinosaurs would have a significant smell with all that dung,
and a good sense of smell would be an advantage in tracking said herds.>

  This sounds like Horner's argument: Ignore the sight, it's unimportant;
instead, focus your attention on the nose, it superceeds sight. Of course, he's
never said that, he simply bends the argument towards the huge size of the
olfactory bulbs and wants you to forget the eyes of the turkey vulture are the
key to SPOTTING dead prey, even if the nose tells you there's something there.
*T. rex* likely used both senses, and ignoring one for the other is to build a
strawman.

<It does not make sense for T rex to attack the pointy end of a Triceratops and
perhaps we should turn the question round, how does a T rex defend itself from
a charging Triceratops?  Perhaps T rex bit the horns to stop being turned into
a kebab.>

  Apparently rex-rendered jaw marks on healed-over trike skulls may indicate
otherwise, but so far the only verified feeding on *Triceratops* data seems to
be anchored on a pelvis with gouges and tooth puncture marks on the underside,
which would, of course, probably only occur after the animal was dead. No one
is arguing a *T. rex* ate off of living animals, leaving them to live for
another chunk, and thus eschewed the corpses of animals it killed or found
lying in the dirt. Sometimes, there _is_ such a thing as a free lunch. It's
unlikely there were enough to sustain rexes indefinately in an ecological
sense.

  Cheers,

Jaime A. Headden

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

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