RE: "Baby"ramus and Age of the Barun Goyot, Djadoktha and Nemegt Formations

[Tim Williams <twilliams_alpha@hotmail.com>]

Gera Mirantsev wrote:

>    I do not think that it hands at the private collection. I saw
> Alioramus cervicals at the PIN collection. Some cervicals are attached
> to holotype.

Is this new 1m-long _Alioramus_ skull also in the PIN collection?  Or just 
the cervicals?

>   Faunal turnover e.g. Pinacosaurus-Saichania-Tarchia. The presence of 
> Saurolophus and a tyrannosaur closest to Tyrannosaurus in the Nemegt argues 
> for a younger age than that of the Djadokhta.

I could be missing something here, but... if two formations in different 
parts of the world show closely related species, why does this mean that the 
two formations must be contemporary?  Taxa are not just parachuted into two 
different continents.  If two species are sister taxa, then the lineage must 
have branched somewhere, with at least one of the two taxa originating in 
some place other than where it ended up.

I agree with Mickey &c: using dinosaurs for biostratigraphic dating is a 
very bad idea.  Just look at how similar _Brachiosaurus_ is to 
_Sonorasaurus_, even though the two are widely separated chronologically.

Cheers

Tim