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

RE: Deinonychus claw use...

  This is certainly something that _I_ would love to do, as I've mentioned on 
this list before. Take all the boring little teeth and quantify the **** out of 
them. The problem lies in that (as currently described) there is but one 
dentary with _in situ_ dentition for North American troodontids (and I am 
unfamiliar with the MOR collections which aver more material than described), 
and there are only four teeth in it. Denticle size relative to crown size, at 
least, changes drastically in this, where posterior teeth have well over 10 
distal denticles, while mesial teeth have but 3-4. Denticle variation is 
perhaps a broader untouched region than assessing strictly denticle number 
along the tooth row, and accounting for the tooth row's length to denticle 
size. I think this shouldn't matter. It is problematic to some degree at least 
because the mesial dentition in Late Cretaceous troodontids is arrayed on a 
mesial curve, meaning that in a lateral view, they become so "clustered" the 
mesial-most first three or four crowns will obscure one another. I touch on 
this in part here: 
http://qilong.wordpress.com/2010/06/19/tooth-denticles-wp5-update/ . It should 
be noted that denticle hooking, mentioned by Fowler et al., does not always 
occur in dromaeosaur teeth, and *Saurornitholestes langstoni* has had some 
teeth referred to it with weak to no hooking. This degree of hooking may be 
positionally relevant along the tooth row, and that may have a greater 
influence on the processing ability of the jaws that mere denticle density.


  Jaime A. Headden
  The Bite Stuff (site v2)

"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 

> Date: Thu, 15 Dec 2011 09:56:08 -0500
> From: tholtz@umd.edu
> To: brushes2@juno.com; DINOSAUR@usc.edu
> Subject: RE: Deinonychus claw use...
> > From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]
> > On Behalf Of brushes2@juno.com
> >
> > John Ostrom would have loved this paper!
> > Alan
> He would have, indeed!!
> By the way, any enterprising student (or other!) with access to advanced 
> troodontid jaws with teeth in them, I offer the following
> short project:
> The authors state:
> "The teeth of troodontids are similar to those of dromaeosaurids in that 
> denticles are reduced or absent on the anterior carina,
> with large hooked denticles on the posterior carina [66], [67]. Troodontid 
> denticles appear proportionally much larger than those of
> dromaeosaurids, and compared to the crown height this is true. However, 
> troodontids possessed many more teeth in their jaws than
> would have a similarly sized dromaeosaurid [67]. For a given fixed jaw 
> length, troodontid teeth are comparatively much reduced in
> size; the crown height of troodontid teeth would have been only about half as 
> much as those of a dromaeosaurid. Therefore it is
> probably more accurate to say that troodontids do not have large denticles; 
> rather, they have short crowns, with similarly sized
> denticles as might be expected for a dromaeosaurid of similar body mass. This 
> makes sense if denticles have a size below which they
> are no longer able to function effectively."
> So, a test of this:
> Measure denticle size in troodontid teeth (and dromaeosaurid teeth, and a 
> couple other basal groups for comparison) AND the length
> of the tooth row of the same individual. Plot the two against each other.
> If the Fowler et al. hypothesis is correct, the troodontid and dromaeosaurid 
> data will plot with each other. Alternatively, it may
> be that the the enlarged denticle size in Troodon et al. will continue to 
> scale above that of dromaeosaurids even when plotted
> against tooth row length rather than a measure of tooth size.
> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu Phone: 301-405-4084
> Office: Centreville 1216
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661
> Faculty Director, Science & Global Change Program, College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
> Mailing Address: Thomas R. Holtz, Jr.
> Department of Geology
> Building 237, Room 1117
> University of Maryland
> College Park, MD 20742 USA