[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: footprint fallacies (was "Large theropod speed record")



Title: footprint fallacies (was "Large theropod speed record
Let me re-phrase the question.  Yes,  trackways provide 'estimates' or 'inferences' rather than 'determinations.'
 
But I have seen inferences on dinosaur speeds made from the relative proportions of the limb bones.  (And opposite conclusions made when discussing the limbs of a rather famous large theropod).  I have also seen physics-based calculations used to infer speed limits based on ability to survive a crash. 
 
It seems to me that trackways, combined with physics-based calculations (that to me seem just as well-founded as the above), represent a step up in degree of confidence in the inferences one is able to draw.  After all, a track does provide a record a living animal;  and calibration of the calculations against living animals provides another step.    
 
Finally, it seems that a theropod as large as Acrocanthosaurus running at a calculated 36 km/hr should have some relevance to the question of how fast the large guys could run.  Trackways showing evidence of running are rare, not unexpectedly.  I am only aware of these 2.  I was just wondering if there were others, and when the same calculations are used, give similar or higher values.   I will add a further question:  what are the plus/minus values attached to these equations?  Even if the answer is a factor of 2, as shown in a figure from Bakker in Dinosaurs Past & Present Vol 1(1987), would not this still be useful?
 
 
----- Original Message -----
Sent: Thursday, February 14, 2002 1:53 PM
Subject: footprint fallacies (was "Large theropod speed record")

Reading the recent news on the new dinosaur tracks in the UK got me wondering.  What is the current trackway evidence for large theropods? 

er....there IS trackway evidence of large theropods :-)
which means they probably walked around, at least some of the time. (At least, trackways indicate that large theropods didn't all fly, or swing from treetop to treetop...)


 I am aware of only two trackways of running large theropods, this recent British study quotes 30 km/hour and Kuban, 1989, quotes 36 km/hr for a trackway in Glen Rose, Texas.  

Right. And as we all know,
speed = distance/time.

And of course, we know exactly how long it took for the dinosaur in question to cover the ground and make that trackway....
oh wait, no we don't. Darn, can someone invent time travel please?

Please please please - while dino tracks are really cool, and give us lots of interesting info, we can NOT - and never will be able to - tell the ACTUAL speed at which they were moving when they left a particular trackway. The figures given in various articles should be taken with a liberal sprinkling of salt. At best, we can estimate the "relative" speed - and say something along the lines of 'dino A was moving twice as fast as dino B'. But even then, you can only compare two critters of the same size and taxon.

emma