Re: Paronychodon-related questions

[bh162@scn.org (Phillip Bigelow)]

Sam Girouard <sampgir@premier1.net>, typing from a couple
blocks away from me, asked:

>6. Have baby plesiosaur teeth ever been found? Refs?>>


I don't know; however you might be interested to know that
some pterosaur teeth are found in marine facies rocks.
Some of these pterosaur teeth *vaguely* resemble plesiosaur teeth
(see my response and ref. to your #7, below).


>7. What theropods are known to have teeth adorned with vertical ridges,
>like in Paronychodon? I already know of Currie, Rigby, and Sloan's work
>with pathological small theropod teeth with similar ridges, and I've seen
>less prominent ridges on illustrations of Ceratosaurus teeth.>>

I am sure someone has already beat me to the punch on mentioning
Spinosaurids as possessing multiple longitudinal ridges on their
enamel (see a ref. below).
I don't know about Baryonyx. Perhaps someone else knows.

Many species of fossil crocs and 'gators also have
very strongly developed multiple longitudinal
ridges on their teeth, but the chances of confusing
these teeth with those from other taxa is quite low.


Also, be aware that some pterosaurs possess multiple
longitudinal ridges on their enamel.  See my response to your
#6 (above).
Also, check out a very useful (and accessable) reference at the bottom
of my post.


>8. Other than Paronychodon and Euronychodon, are there any small theropods
>known to have teeth without denticles (serrations) on either the anterior
>or posterior carinae, or both?>>


Spinosaurids often have extremely fine denticles, some so fine
in fact, that some teeth appear to be serration-less
without magnification. Kellner and Mader (1997) found a tooth with
(supposadly) no serrations.
The following is only speculation on my part, but I wonder if
there is a relationship between the evolution of
multiple longitudinal ridges on enamel and a general evolutionary
fining (or loss) of denticles on the carinae.


>9. Does anyone know of any isolated theropod teeth occurring in marine
>sediments?>>

Horner's (1979) census of the Dinosauria from the marine Bearpaw Shale
contained no theropod material.  I am not aware of any updates to
this now rather dated list.


References:

Kellner, A. and Mader, B.J. 1997.  Archosaur teeth from the
    Cretaceous of Morocco. Journal of Paleontology 71(3):525-527.


Horner, J. R. 1979. Upper Cretaceous dinosaurs from the Bearpaw
   shale (marine) of south-central Montana with a checklist
   of upper Cretaceous dinosaur remains from marine sediments in
   North America. Journal of Paleontology, volume 53(3):566-577.


                     <pb>


--
                 Phil Bigelow
                 bh162@scn.org