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RE: Bird vs. theropod dinosaur tracks/trackways



Question,
        Its not clear from the email whether all birds today use the
same walking stance that (probable) cretaceous shorebirds used.
How about the rattites? 
        The question is of interest if the walking stance of modern birds 
is an accidental result of an evolutionary bottleneck rather than an
adaptation to flight. 
G. Derkits
> ----------
> From:         Darren Tanke[SMTP:dtanke@dns.magtech.ab.ca]
> Reply To:     dtanke@dns.magtech.ab.ca
> Sent:         Sunday, April 11, 1999 9:55 PM
> To:   dinosaur@usc.edu
> Subject:      Bird vs. theropod dinosaur tracks/trackways
> 
>  We recently had a guest speaker at Tyrrell and he had both Middle
> Cretaceous shorebird footprints/trackways and theropod (large and small)
> tracks/trackways. How to tell them apart? It was shown that birds show a
> greater angle apart between the outside toes; walk pigeon-toed (with the
> toes turned in towards the midline) and a straight line can be drawn
> inside
> (in between the tracks) a straight bird trackway and not touch any of the
> footprints. For theropods? Trackways are in a nice straight line and the
> toes pointed more or less forward.
> 
>  Birds and theropods are widely accepted as being very closely related
> yet,
> by the middle Cretaceous, birds were already walking like birds today, and
> unlike their theropod relatives. Which raised some questions at the talk
> and
> subsequently, for which I could not get clear answers. So, I thought I'd
> raise them here for discussion.
> 
>  1). Why do birds "waddle" (and thus turn their toes inwards) and
> theropods
> apparently did not (as manifested by the trackway evidence)? Someone
> thought
> theropods did "waddle", but due to their greater height the direct effect
> of
> this was somehow "lost" by the time the foot touched the ground (whatever
> that meant!).
>  2). What skeletal or other morphological feature(s) cause a bird to walk
> pigeon-toed and theropods not?
>  3). Could the difference be related to behavior? A suggestion was that
> "waddling" bird tracks were of feeding birds while those of theropods were
> simply walking from point A to B.
>  4). Theropods are able to put one foot directly in front of the other,
> birds apparently not. True? If so why? I'm not a bird footprint expert,
> but
> if memory serves, I think I have seen some rather straight trackways with
> the middle toe pointing more or less forward.
> 
>  Given the close relationships between both groups (one group?!), I find
> the
> difference in their walking capabilities/strategies quite striking. Ideas
> anyone?
> 
>  Darren
> 
>  
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> FAEVUS QUAESITOR SCIENTIA                                  FODERE AUT
> CADERE
> 
> DARREN TANKE, Technician I, Dinosaur Research Program, ROYAL TYRRELL
> MUSEUM
> OF PALAEONTOLOGY, Box 7500, Drumheller, Alberta, CANADA  T0J 0Y0 and:
> 
> Senior editor of: Annotated Bibliography of Paleopathology,
> Dento-Osteopathy
> and Related Topics. 12,702 citations as of January 28, 1999.
> For details, visit the bibliography homepage at:
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