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Re: Acrocanthosaurus locomotion

<< If that very reasonably cautious attribution is correct,
the Paluxy River valley theropod trackways might be a good
place to attempt to evaluate and contrast Acrocanthosaurus
speed(s) as calculated using more traditional methods as
applied to trackways, with those recently calculated for T.
rex without using trackway evidence. Of course, it wouldn't
prove anything, but a comparison might be interesting for
the two animals whose sizes are reasonably constrained. The
largest theropod trackway there in Texas certainly provides
a pretty good indicator of overall size and approximate
weight of the trackmaker.>>

Well ... The closest _A.atokensis_ we have if we compair
Femur lenght is NCSM 14345 which, along with the _T.rex_ MOR
555, has a femur of about 1280 mm. The legs of the
Acrocanthosaurus are about 0.90 the lenght of MOR 555's
legs, but the overall animal is MUCH lighter. Anderson's
method gives 2.4 tonnes to NCSM 14345 and 4.16 tonnes to MOR
555. Vollumetric estimates will gives something along 3 for
the Allosaurid and 6 for the Tyrannosaurid. Both leg lenght
is similar, but Acro is half the weight of the rex. So no,
your right, that wouldn't prove anything.

On a side note, however, IF the 12.1 m/sec-1 (43.5 km/h or
27 mph) trackway really belongs to the Acrocanthosaurus
(With a 5.65 m stride), that would indicate a pace of 2.15
strides per second, so my take is that it way obviously
having an aerial phase ...

Thomas Miller

Boîte aux lettres - Caramail - http://www.caramail.com