[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: rampant speculation



I wrote:

<<There were no 15-20 feet ornithischians other than Maastrichtian 
*Rhabdodon*.>>

George Olshevsky (Dinogeorge@aol.com) wrote:

<What about Stegosaurus, Dacentrurus, Tenontosaurus, a number of ceratopians, 
and a number of
ankylosaurians? These would fall into this size range.>

  I was referring, as was the individual to whom I was replying (Justin Tweet) 
to latest
Cretaceous ornithopods, excluding EK, mid-K, or Jurassic species. However, 
George does bring up a
few Campanian taxa that can be included, such as the Dinosaur Park, Judith 
River, Belly River,
Milk River, and Two Medicine ceratopids like *Styracosaurus*, *Einiosaurus*, 
*Achelousaurus*,
*Centrosaurus*, *Monoclonius*, *Chasmosaurus*, etc.... These species are of a 
different paradigm
than the "small or medium-sized" taxa that Justin implies as in 
*Thescelosaurus* or *Dryosaurus*
in anatomical specialization [or generalization as used]. The skull of 
*Rhabdodon* is similarly
specialized as an iguanodont jaw is, with several levels of vertically stacked 
teeth forming the
hyper-herbivorous battery that defines this level of ornithopod evolution 
(Rhabdomorpha +
Iguanodon + Hadrosaurus may be a good way to state the node).

  This leaves very few generalized taxa at the end of the Cretaceous ... the 
only purported
omnivores in Campano-Maastrichtian time are oviraptorosaurs, ornithomimosaurs, 
troodontids, and
*Thescelosaurus.*


=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

__________________________________________________
Do You Yahoo!?
Make international calls for as low as $.04/minute with Yahoo! Messenger
http://phonecard.yahoo.com/