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RE: Rauhut and Xu on Tugulusaurus and Phaedrolosaurus



Jaime Headden wrote:

The authors consider the leg to be
diagnostic and comparable to other species, establishing the new taxon
*Xinjiangovenator parvus*. There are some problems I am having with this,
however, including the establishment of taxa based on a single autapomorphy, so
I am taking a closer, critical look.

To play devil's advocate: What is wrong with establishing a taxon upon a single autapomorphy? As long as a genus or species has ONE character that can be used to distinguish it from any other genus or species, it is valid in my book. _Archaeopteryx_ has precious few autapomorphies (maybe only one), but it is indisputably a valid genus.


I would go further and say that, even in the apparent absence of autapomorphies, a unique combination of characters is enough to validate a genus or species. For example, Rauhut recently upheld _Genyodectes_ as a valid genus based upon the unique combination of characters displayed by the jaw material, even though it had no autapomorphies.

BTW, I enjoyed these summaries of _Tugulusaurus_ and _Xinjiangovenator_ - thanks Jaime. I don't have much confidence that _Xinjiangovenator_ and _Bagaraatan_ form a separate clade of maniraptorans. I wonder how both _Tugulusaurus_ and _Xinjiangovenator_ compare to _Yixianosaurus_?


Tim