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Re: Tyrannosauroids Imploding Further

Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<I wouldn't be so quick to judge.  This paper itself describes apomorphic
dental characters of different tyrannosaurid taxa (mesial carina reaches
crown base in Daspletosaurus; "in Daspletosaurus torosus and Tyrannosaurus
rex, the lingual surface of each of the third left and right maxillary
crowns in LACM 28471 bear a prominent apicobasal ridge that creates a
crease adjacent to the mesial carina"; etc.).  So once horridus,
periculosus and such are studied, it may be possible to refer them to
known taxa.>

  I have no place to judge. I assess based on the given data, but my
assessment is prone to change given more or less data. If anyone can
demonstrate whether the type crowns of these species are second, third,
fifth, or eigth maxillary, left and right, or even dentary positions, I
would be amazed at their ability to put isolated teeth in non-existent
jaws, and determine that such teeth went to such distinct species, binding
these taxa by their positional dental morphology, rather than varied
between them; if so, I'll buy them a cigar. It should be clear there have
been a good deal of issues placed on what isolated teeth are. Finding a
non-dinosaurian skull with *Revueltosaurus*-type teeth in it is, I'm sure,
a shock to those thinking it was an ornithischian (one of the posters at
SVP). Such can happen across species, as well, especially when these
species are primarily similar in tooth form (Morrison lateral theropod
teeth tend to differ only in a few cross-sectional details [tear-shaped,
lozenge-shaped, or ovate with apices] and are usually differentiated upper
from lower only in relative curvature, root length, and size ... unless
it's a large posterior maxillary teeth that is the same size and shaped as
a mid-dentary tooth of a smaller individual). Hopefully, assessing
tooth-based taxonomy will allow the shocking 114 tooth-based dinosaur taxa
(that I know of) to be worked on more in keeping with their more
indeterminate nature.

  Have I mentioned how (and extensively, why) I dislike tooth-based
taxonomy? Does anyone think it is really possible to take an isolated
little ziphodont tooth and tell me where in the skull it belongs, and thus
to which taxon? If the closest oneu can get is cf. Velociraptorinae, then
it's a failed experiment, since it puts us no further near the goal of
identifying isolated teeth to _species_. If you've put it even nearer, I'd
like to know how one was able to determine this tooth did not belong to a 
species, similar yet distinct, from that which it's been applied to. This
is an important issue that has NOT been addressed yet. Yes, I'm getting to
it. Can one also separate ontogenetic variation, or deciduous versus
permanent morphologies, from one another, adequately, and still get
through the above issues?

  Incidentally, can someone name whoever may have published the phrase
"the tooth, the whole tooth, and nothing but the tooth?" as well as the
statement about teeth having sex with teeth and giving birth to more
teeth? I am just looking for some cute anecdotes with sources (pagination


Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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