Re: einiosaurus, achelousaurus?

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>>If so, can anyone provide some basic details such as age,
>>classification, locale of findings, basic description of any distinguishing
>>features?
>

Sampson, Scott D.  1994.  Two new horned dinosaurs (Ornithischia:
Ceratopsidae) from the Upper Cretaceous Two Medicine Formation, Montana,
USA.  Journal of Vertebrate Paleontology, 14 (Supplement to 3), 44A.

They are from the late Campanian (= Judithian) stage, and from Montana.
Einiosaurus has two spikes projecting from the frill, low rounded
brow-horns, and (in some individuals) a narrow hooked "can-opener" nose
horn.  Achelousaurus also has two large spikes on the frill, and adults
have lumpy mounds for both brow and nose horns.

They are members of the Centrosaurinae (subfamily of Ceratopsidae).
Sampson, Horner, and others have suggested that
Einiosaurus-Achelousaurus-Pachyrhinosaurus represent an ancestor-descendant
series.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.