RE: Chinese dromaeosaur tracks

[Tim Williams <twilliams_alpha@hotmail.com>]

Dan varner wrote:

> I don't have access to the paper at the moment, but I would like to know why
> troodonts were not considered as the track makers. 

The authors do not dismiss the possibility that the track maker was a 
troodontid.  They are certainly confident that it was a deinonychosaur, as 
reflected in the paper's title: "Behavioral and faunal implications of Early 
Cretaceous deinonychosaur trackways from China."  The track macker's putative 
identity as a dromaeosaurid is based essentially on size and provenance...

"The Deinonychosauria comprises two clades, the Troodontidae
and Dromaeosauridae.  Basal members of both lineages
are remarkably small animals (Makovicky et al. 2005; Xu and
Norell 2004; Xu et al. 2002), but large dromaeosaurids, with
body lengths in excess of 3 m, are known from the Early
Cretaceous of North America (Kirkland et al. 1993) and
from the early Late Cretaceous of Mongolia (Perle et al.
1999), whereas large bodied troodontids only occur in Campanian–
Maastrichtian sediments on either continent, and even
then are not known to attain dimensions necessary to qualify as
potential _Dromaeopodus_ track makers (Makovicky and
Norell 2004).  Therefore, the _Dromaeopodus_ track maker
was most parsimoniously a large dromaeosaurid as inferred
from both phylogenetic understanding of body size evolution
(Turner et al. 2007b) and consideration of geological age and
paleobiogeography."



Cheers

Tim





  



_________________________________________________________________
Climb to the top of the charts!  Play Star Shuffle:  the word scramble 
challenge with star power.
http://club.live.com/star_shuffle.aspx?icid=starshuffle_wlmailtextlink_oct