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RE: Triceratops running speed



Ville Sinkkonen (ville_sinkkonen@artic.net) wrote:

<I have readen the book "the dinosaur heresies" and there was
wery good proof that ceratopsian have full erect posture. If the
ceratopid is warm-blooded and fully erect posture then i think
that the runing speed is 30-40 Km/h . T-rex runing speed is also
speculated to be same numbers. But this is only my oppinion and
i'm not expert.>

  There is a good deal to consider in measure of the forelimb
posture and general carriage (and thus gait and speed) in any
ceratopian, especially the ceratopid *Triceratops.* Rohlf
Johnston argues (in 1990) that the forelimb of *Torosaurus* was
completely incapable of an erect, strait-legged posture as seen
in elephants. Paul and Christiansen (1999) show that, which
Bakker (1986, Dino Heresies) did not consider, the rhinoceros
(Bakker's main comparison) does not have an erect-legged
forelimb, unlike an elephant.

  Most of Bakker's (1986) stems from the apparent similar
ecology he assigns to the Hell Creek and the modern (Recent)
Kenyan savannah.

  That the high speed of a ostrich-legged animal like
*Tyrannosaurus* must have meant it chased its prey and thus the
prey must also be high-speed runners, is a viscious cycle that
needs to be broken.

  The forelimb in ceratopids is held constantly flexed at the
elbow, and even Paul and Christiansen show that the elbow at
this point was slightly bowed outward. Tracks (Thulborn and
Lockely have both described these, also represented by Paul and
Christiansen) show that the forelimbs were held in the same line
as the hindlimbs, if not just a slight bit outside them, and
turned slightly inward, so that the forefeet were slightly
pigeon-toed. The alternative model, offered by Johnston,
suggests that the forelimb was bowed and held out at the elbow,
but this places too much space between the forefeet; Paul and
Christiansen offer that the solution lies not in the joints of
the forelimb, but in the shoulder's position and the
articulation of the anterior dorsal ribs and slope of the
veretbrae at the front of the trunk. The configuration they
offer (there have been several posts on this paper, from
_Paleobiology_, some time back, check the archives under "Paul
and Christiansen" and "stance") pulls the glenoid into a
horizontal position, the shoulders closer together, and the
forelimbs very nearly perfectly match the tracks of
*Ceratopsipes*, thus leading to the concept of perhaps the most
accurate model yet of the forelimb, drawing from Rohlf's work
and thus not contradicting him for the most part. The lack of
any pronation of the arm must be taken into context, Paul and
Christiansen warn: the contact between ulna and radius is a pair
of flat facets that would have prevented any rotation of the
radius about the ulnar axis, thus pronation was restricted
completely.

  The forelimb has the ability to swing back and forth, and this
lengthens the stride, but it is unlikely, given the hindlimb
morphology, that the animal could have attained cursorial speeds
of more than 30mph. While a speed for the animal would need to
be carefully calculated (not the same set of equations used for
bipedal animals) the longer femur to tibia, the shortness of the
forelimb and the relative effective forelimb length (sensu peri
Farlow), the form of the ilium and lateral relocation of some
propulsive muscles, short cnemial crest and reduction of
long-arm levers in the limbs, argue that the speed of a
ceratopid was not as great as that even of a rhinoceros;
especially given the mass of the animal was greater by degrees
of magnitude.

  Thus, it is unlikely in this person's opinion that the speed
of *Triceratops* was not any better than that of a full 7-ton
*Tyrannosaurus* who couldn't run faster than 30mph for fear of
tripping to death (Farlow et al., 1995, _JVP_ 15).

=====
Jaime A. Headden

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

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