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Dinosaur Lips (For now, Not Noses)

Although some anatomical (and functional) linkage may have been going on, I 
for one will be following Jon Wagner's fair-minded suggestion to stay away 
for now from commenting on the nose issue until Larry Witmer's paper is out. 
Lips, however, are still an appropriate subject. Some List Members have 
already pointed out the old bugaboo in vertebrate paleontology regarding 
this, re: what can we (or can't we) know without the osteological evidence? 
You're always taking a theoretical  "risk" when speculating about soft-tissue 
anatomy, and in light of this the sensible approach is the parsimonious one: 
to base as much as you safely can from close dinosaur relatives (crocs and 
birds), but not to be a slave to their limitations, while at the same time 
drawing conclusions from the biological needs of living tetrapods. Extinct 
and living crocs have much valuable light to cast on dino anatomy and 
behavior, but living forms are moderately specialized, and evolved away from, 
mainstream archosaur evolution; this is a shorthand, but by no means flip, 
answer to Chris Brochu's comment on 8/08, "But the simplest prediction for 
now is that lips were lacking." The osteology of dinosaur premaxillaries, 
maxillaries and dentaries to me are different enough from those of 
crocodylomorphs to suggest that there was a possibility of a very different 
overlaying morphology of soft tissue. Mike Skrepnick's comments, based on his 
and Phil Currie's tyrannosaurid studies, which refer to the perceived gap 
between the "V" shape formed by the shape of the mandibular symphysis (and 
its tooth row) and the "U" shape of the premax & maxillaries, are I believe 
astute observations, which also support the idea of space for moist, fleshy 
inner mouth tissue and, by implication, the need to conserve this from 
moisture loss. As artists and paleontologists, we have to speculate to some 
extent if we want to in some way depict dinosaurs graphically as the living 
beings they once were, subject to the same biological constraints as living 
forms and yet having in all probability unique adaptations that were unique 
to themselves, and quite different from other tetrapods. We must first ground 
our anatomical interpretations on the osteology we have at hand, but we must 
also employ what I would call "parsimonious creativity" in attempting to 
bring to life what the bones alone cannot us. 

Mark Hallett