Re: Ceratonykus oculatus

["T. Michael Keesey" <keesey@gmail.com>]

On Mon, Jan 12, 2009 at 4:29 PM, Tim Williams <tijawi@yahoo.com> wrote:
>
> Alifanov, V.R. and Barsbold, R. (2009). _Ceratonykus oculatus_ gen. et sp. 
> nov., a new dinosaur (?Theropoda, Alvarezsauria) from the Late Cretaceous of 
> Mongolia.  Paleontol. Zh. (Russ.) 2009, 1: 86â99.
>
>
> Abstract: "A new dinosaur, _Ceratonykus oculatus_ gen. et sp. nov. 
> (Parvicursoridae, Alvarezsauria), from the Upper Cretaceous (Baruungoyot 
> Formation) of Mongolia is described based on a fragmentary skeleton.  It 
> differs from other alvarezsaurians in many characters, including the short 
> femora, long tarsometatarsals, and considerably reduced third metatarsals.  
> The carpometacarpals contain spikelike bones.  The natural endocast of the 
> new taxon shows large acoustic tubercles, the ventral position of the optic 
> lobes in the midbrain, and the absence of a vertical flexure at the brain 
> floor. The data obtained cast doubt on the taxonomic position of 
> alvarezsaurians in the Theropoda."
>
> The last sentence can be taken with a grain of salt; but it would be 
> interesting to know the rationale behind their claim.  It doesn't appear to 
> be "alvarezsaurs-are-birds/birds-are-not-dinosaurs" boilerplate (the title 
> implies that the authors believe them to be dinosaurs, at least).  Most of 
> the paper is in Russian, although the classification is in English (family 
> Parvicursoridae, subfamily Mononykinae).

As stated, it could also mean that alvarezsaurs are bizarre enough
that, in the authors' opinion, they warrant a new suborder. Or that
they are avians (sensu lato) and therefore not part of a paraphyletic
Theropoda. (It does say "taxonomic position", not "phylogenetic
position".)

I skimmed the text trying to find where they might be allying
alvarezsaurs to some other group. Seeing as I don't know Russian
(although I do know Cyrillic), I could certainly have missed
something, but it seems that they mostly just discuss coelurosaurian
taxa. One exception is a mention of Iguanodon on page 95, probably in
reference to its spiky thumb. (This paragraph does mention the
carpometacarpus.) There is also mention of Ornithischia on page 97,
but I have no idea what the context is.

-- 
T. Michael Keesey
Technical Consultant and Developer, Internet Technologies
Glendale, California