RE: Lack of Running Giant Theropod Tracks

[Sim Koning <simkoning@msn.com>]

Augusto Haro wrote:
 
> I think that the solid contact of the functionally one-piece that is
> the skull with horns and snout indicates that if flexibility in the
> neck is to protect the snout, by thrusting it forwards limitedly, it
> would also limit the horns of entering too much into the body of the
> predator. However, there are triceratops skulls were the horns direct
> more dorsally from the skull (at a 90º angle from the skull long
> axis), and which would make this problem unexistent for those
> individuals.

 
   This is going to sound silly, but bear with me, because I just noticed 
something. Grab you scale dinosaur models that you have sitting around (you got 
to have some) and hold the Triceratops's horns up to the Tyrannosaur's torso. 
If a Triceratops, or similar ceratopsid charged a T. rex, its rostrum would 
-pass under- the Tyrannosaur's thorax, while the full length of the orbital 
horns would be driven into the body, potentially rupturing the heart or lungs. 
Once the full length of the horns were plunged in to the body, the rostral horn 
may have further lacerated the underbelly. What I see is a set of horns very 
well "designed" to kill a large Tyrannosaurus. In fact this is now my next art 
project: a charging Triceratops killing a T. rex : ) I'll get it scanned into 
deviant art when I'm done and send you a link. 
 
 
> Maybe, but in this case, as a problem for the Triceratops snout, you
> still have the close to the midline hindlimbs, which are largely made
> in bone and very massive. Being that the torso may have been nearly
> horizontal in Tyrannosaurus, perhaps in a frontal attack horns may
> first found the chest, and perhaps here the snout is less of a
> problem.

 
Exactly what I was thinking. In a face off, a T. rex would be taking a massive 
risk if it tried to turn to escape, as it would expose its flank and the above 
scenario would be nearly perfect provided the Triceratops was careful to miss 
the legs in the charge. 
 
> Well, how erect you are is not necessarily related to velocity.
> Sprawling lizards can be faster than mice or birds in their same size
> league. Perhaps even large lizards can be as fast as or faster than
> semi-erect crocodilians of their same size.
 
Yes, but how many lizards can actually 'gallop'? As far as I know Crocs are the 
only (so called) reptiles that can and they have a more erect posture. Now I 
don't want to take that too far, since my statement about galloping crocs was 
more a comment on credulity than actual animal morphology, which is hardly 
scientific (or even good philosophy) for that I apologize.
 
 
> However, I think a problem in comparing crocodilians with Triceratops
> is that the former have saddle-shaped shoulder joints which permit to
> protract the humerus by rotating it laterally, so as to direct
> cranioventrally the forelimb to lessen the impact of the fall after a
> jump. In ceratopsians, the glenoid is not saddle shaped and directs
> caudally, precluding the lateral excursion of crocodylians to direct
> the humerus cranioventrally. The most protraction the humerus can
> perform is the vertical, as far as I can check, along its limits in
> the glenoid, assuming the scapulocoracoid to direct obliquely
> (caudodorsally). For the humerus to be directed cranioventrally, it
> seems to me that the scapulocoracoid should be set close to the
> horizontal, which is unlikely anatomically. If Triceratops did not
> have its humerus cranioventrally directed, it would be more difficult
> for it to receive the impact with the ground after a jump of those
> that trotting implies.
 
  I was reading through Greg Paul's paper on ceratopsians and how they are most 
analogous to rhinos in morphology, and I noticed that in rhinos the humerus 
doesn't seem to pass the vertical in a gallop

http://www.youtube.com/watch?v=0J0Xq0X_7lU
 
However, the palms of the ceratopsid manus seem to be rotated somewhat 
medially. How much do you think that may have impacted their capacity to gallop 
at high speeds?
 
> The long horns can also be lethal in many antelopes and bovids in
> general. There are cases of them impalling predators, yet this does
> not preclude predators of making a living of these animals. Tigers
> regularly feed on boar and warthogs are at least occassionally prey of
> many predators
 
I concede your point.
 
> That may well be, but I do not know much modern cases of archosaurs
> hunting grupally, although crocs are gregarious and there seem to be a
> few birds with social hunting strategies.
 
I really don't like that argument at all. Imagine if there was another mass 
extinction and bats were the only mammals that survived; now imagine some 
future paleontologist decided that it was silly to think of Lions hunting in 
prides all because they do not observe pack hunting among extant "neobats". I 
think it's more helpful to ask *why* animals hunt in packs. 
 
Simeon Koning