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RE: Ceratonykus braincase described



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> Date: Thu, 28 Apr 2011 12:37:31 +1000
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Ceratonykus braincase described
>
>
> So I can see why Alifanov and Saveliev would not want a "typical
> theropod" like _Haplocheirus_ to be ancestral to Late Cretaceous
> alvarezsaurs like _Ceratonykus_ and _Shuvuuia_: it destroys their
> arboreal hypothesis.

No, it is just as easy to imagine that alvarezsaurs passed through their 
hypothetical sloth-like arboreal phase in the Early Cretaceous, in forms more 
derived than *Haplocheirus*.

> Instead, _Haplocheirus_ is "tentatively" regarded by Alifanov and
> Saveliev as a relative of the Coeluridae or Compsognathidae.
> Personally, I would love to see compsognathids on the line leading to
> late Cretaceous alvarezsaurs: it would fill in the Late Jurassic -
> Early Cretaceous ghost lineage, and show key steps in the
> transformation of the forelimb. But, alas, a
> compsognathid-alvarezsaur clade is not what current phylogenetic
> analyses are showing (although certain phylogenies show
> Compsognathidae and Alvarezsauria as successive outgroups, which is
> interesting IMHO). In any case, a compsognathid-alvarezsaur link is
> not what Alifanov and Saveliev are arguing, because they remove
> Alvarezsauria from Theropoda altogether! Outside of the work on the
> _Ceratonykus_ brain cast, the ecomorphological component of the
> Alifanov and Saveliev paper is bad science. Linking alvarezsaurs to a
> hypothetical, arboreal, non-theropod ancestor reminds me of the
> efforts by Feduccia &c to link birds to a hypothetical, arboreal,
> non-theropod ancestor (presumably not the same imaginary ancestor).

Do they suggest any hypothesis of what alvarezsaurs ARE, if not theropods?