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RE: Making Lip of It


     I'm glad you posted this article. My girlfriend is a science 
illustrator and she has been motivating me to start drawing with more 
frequency. I've started drawing dinosaurs again, but I've 
been growing frustrated with this lip issue. It's not exactly a small 
problem, as it has a dramatic effect on the way a dinosaur looks. I've read 
through your article a few times and I have some things I'm hoping to 
discuss with people more knowledgeable than myself.

     In your article you state that the placement of the foramina seem to 
indicate lizard-like tendenous 'lips' similar to those found on lizards. I 
often found this somewhat convincing in the past, but after spending the last 
few days looking at dozens of pictures of crocodilian and squamate skulls, 
while at the same time reading arguments from others on this list, I'm leaning 
more and more to the lipless side of this debate. Though I do have problems 
with some of the arguments being put forward by both sides. For example, in old 
post on this list Tracy Ford argues that the presence of an overbite strongly 
suggests a lipless morphology, since lizards tend to have interlocking teeth 
and no overbite. However, from what I can tell, geckos have an overbite rather 
similar to that of some dinosaurs.


Now on the other hand, so do some crocodilians. So, I don't find the presence 
or lack of an overbite very convincing either way. What it does suggest, to me 
at least, is that they would have been able to at least partially seal their 
mouths without the aid of lips. 

     Arguments that revolve around foramina don't seem to help much. If they 
are diagnostic of anything, it seems to be degrees of sensitivity and 
vascularity of the skin around the jaws. The nutrient foramina found around the 
jaws of spinosaurids follow a single channel until they reach the tip of the 
snout, where they begin spread out or form several rows. This suggests to me 
that the foramina had more to do with sensitivity of the mouth than to the 
presence of lips. Deinonychus has a double row of foramina on the maxilla while 
they seem (to me) to be lacking on the rostrum. So perhaps they lacked lips 
altogether and possessed a keritanous proto-beak? I know you do not like this 
idea, but splitting the lip tendon/ligament seems only to be a problem if you 
assume they had lips in the first place. 


    If you look at the jaws of a dwarf crocodile, you will notice that they are 
practically covered in foramina. I know some have argued that the liplessness 
of crocs is probably due to their aquatic nature, but then I have to ask why 
this did not present a problem for terrestrial crocs such as Kaprosuchus or 
Simosuchus, both of which were fully terrestrial, with one likely an herbivore. 


    In the case of Simosuchus, the placement of foramina does not seem to 
differ greatly from what we see in some dinosaurs such as Deinonychus. You may 
notice that there is a cluster of foramen located on the maxilla, while they 
are lacking on the rostrum. Perhaps the tip of the snout was covered with a 
hard keritanous covering, perhaps a sort of proto-beak? This leads me to my 
next point: I suspect that most, if not all ornithodiran archosaurs were 
'lipless' and this may have been why so many lineages tended to evolve a beak 
of one form or another. Maybe a lipless mouth is a necessary precursor to a 
beak. I suspect that a beak may have often started out has a hard covering on 
the snout that gradually worked its way back along the jaws, replacing the 
teeth in the process. But as you point out, a beak of this nature may not have 
been able to coexist with lizard like lips. This seems to present an argument 
against dinosaurs having lips since we know that many archosaur lineages 
evolved beaks independently. 

    So, when I consider these points, I am inclined to depict most, if not all 
dinosaurs without lizard like lips and I suspect the beaked, lipless depictions 
of dromaeosaurids is the most probable. Of course, I am by no means an expert 
on this subject, but since there is so much disagreement, I am forced to pick 
one option or the other unless I intend to draw them with blank mouths. 

Simeon Koning.

> Date: Sun, 18 Sep 2011 02:19:13 -0600
> From: qi_leong@hotmail.com
> To: dinosaur@usc.edu; Vert.Paleo.Mailing.List@listproc.usc.edu
> Subject: Making Lip of It
>   I'm going out on a limb and posting my (sometimes) controversial opinion in 
> regards to that perennial problem of dinosaur lips. In this, I will 
> temporarily gush over Larry Witmer's biology work while at the same time 
> taking an aim at a cherished childhood icon, "Crash" McCreery's 
> "velociraptors" from _Jurassic Park_. The conclusions are anything but, but I 
> had a lot of fun making the art. Check it out at my blog, or follow the 
> direct link: http://qilong.wordpress.com/2011/09/18/making-lip-of-it/ . At 
> over 3,500 words, it's my largest single piece written exclusively online, 
> and represents the culmination of a few lines of data regarding jaw structure 
> and soft-tissue analogies. As I state in the post, I'm an amateur and would 
> appreciate positive criticism.
> Cheers,
> Jaime A. Headden
> The Bite Stuff (site v2)
> http://qilong.wordpress.com/
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
> "Ever since man first left his cave and met a stranger with a
> different language and a new way of looking at things, the human race
> has had a dream: to kill him, so we don't have to learn his language or
> his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
> Backs)