Re: Fastovsky vs Archibald

[Tim Donovan <uwrk2@yahoo.com>]

--- GUY LEAHY <xrciseguy@prodigy.net> wrote:

> Assuming the identification of
> Hypacrosaurus from the lower Hell Creek is correct,
> this may have no more significance than does the
> absence of Edmontosaurus from the upper Horseshoe
> Canyon Formation, 


  But what about the lower Scollard, equivalent to the
upper Hell Creek? Lambeosaurs may have been excluded
from the upper Hell Creek, preferring drier habitats
but why aren't they known from the Scollard, farther
inland? I think that was at least as far inland as the
upper Horseshoe Canyon but it has no known
lambeosaurs.



>due to the Signor-Lipps effect. 


  Or a change from the near coastal habitat
represented by unit 1 to the farther inland habitat of
unit 4?


> In the Lance/Hell Creek, specimens of Anatotitan
> appear to be restricted to the upper part of the
> unit.

 As the most derived hadrosaurine, could it have only
evolved by then?




                
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