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Re: PACHYRHINOSAUR LINEAGE



> Are _Einiosaurus_ and _Achelousaurus_ the two new centrosaurines 
> regarded as intermediate between _Styracosaurus_ and 
> _Pachyrhinosaurus_? 

     "Marine transgressions and the evolution of Cretaceous dinosaurs"
     Horner, Varrichio, & Goodwin
     Nature 358 (July, 1992) pp. 59-61

     "Two new horned dinosaurs from the Upper Cretaceous Two medicine 
     Formation of Montana; with a phylogenetic analysis of the 
     Centrosaurinae (Ornithischia: Ceratopsidae)"
     Scott Sampson
     Journal of Vertebrate Paleontology
     15(4), December 1995 pp. 743-760 

     The first article makes more or less that claim.  Sampson's article 
is a little more conservative and simply suggests very close ties between 
the genera.  
     I'm working on enties on _Acelousaurus_ and _Einiosaurus_ for the 
DinoPages web site right now, but it probably wont get done till the end 
of the month as I have other things I need to get done in a hurry.  For 
these two genera, I have the above references, the Natural History 
(July, 1995) article by Sampson, and a paper on the _Einiosaurus_ bone beds 
by R. Rogers (Palios, 1990).  Does anyone else have additional references?  
     Also, in the Nature paper, _Einiosaurus_ and _Achelousaurus_, not yet 
named, were referred to as "transitional taxa B & C".  What is 
"transitional taxa A"?  It has a _Styracosaurus_ like skull, but only two 
parietal spikes, like _Achelousaurus_ and _Einiosaurus_.    

LN Jeff