Joe Here. Thanks for the update on Mosasaur bite marks. Some friends and I were
recently in Southeast Alberta. Found many ammonites (Placenticeras). I had an
eye out for 'bite' marks but no evidence.
 
      Interesting re comment on 'green' bite marks on dinos. Here in Alberta we
can collect almost unlimited amounts of dino bone. Bite marks, however, are
rare. Find maybe 2 or 3 a year after turning over several hundred bone pieces.
The ones we find are usually from small raptor(small predatory dinos). Part of
the reason is that fossil bones, when freshly exposed through weathering,  will
shatter and disintegrate via frost action  if they have large fractures such as
those from Tyrannosaurid bites.
 
        Re mollusca predation. A couple summers ago Nora and I were collecting
non-marine fossil mollusca in a Late Cretaceous deposit (mollusca are often
found in same deposits as dino bones). Mostly viviparidae. A few unios.  I
picked up an Unio with a small oval  hole in it. I thought it there was a piece
of chert in the hole. The fossil Unio was an 'iffy' specimen so I wacked it
with my rock hammer. Out popped a raptor (Dromaeosaurus) tooth. The piece of
chert was actually a raptor tooth left behind by a dining predator.  I suppose
little raptors munched on bivalves much in the same way as a coyote will today.
 
 
 
Andrew K. Rindsberg wrote:
 
> Some time ago, Nora Bryan wrote about the difficulty of distinguishing
> limpet scars from bite marks on fossil ammonites. Erle Kaufmann interpreted
> the holes as punctures made by mosasaurs in the 1960's. Recently, Kase and
> others (including Dolf Seilacher) convincingly showed that some holes on
> ammonites are limpet scars in:
>
> Kase, T., Johnston, P. A., Seilacher, A. & Boyce, J. B. 1998. Alleged
> mosasaur bite marks on Late Cretaceous ammonites are limpet
> (patellogastropod) home scars. Geology, 26(10): 947-950.
>
> What you have to realize is that the eminent researchers did not study the
> same ammonites, though they did work on specimens from the same age and
> formation. Seilacher wanted to examine Kaufmann's ammonite, but this
> specimen was lost several years ago, so it is no longer available for
> study. If it has mosasaur bite marks, no one can tell for sure now. It
> could be that they are both right in different cases. As Walt Whitman said
> (more or less), "And if I contradict myself, very well, I contradict
> myself. I am large; I contain multitudes." Nature might say the same.
>
> David Schwimmer (the REAL vertebrate paleontologist living in Columbus,
> Georgia, not the actor on "Friends") has documented bite marks of sharks in
> Cretaceous dinosaur bones. He can distinguish marks made in "green" bone
> (that is, fresh bone) and in old, brittle bone. As to whether sharks made
> the holes, he has excellent evidence: Some of the holes have shark teeth in
> them. Sharks shed their teeth frequently and they sometimes rip out while
> they are feeding.
>
> Andrew K. Rindsberg
> Geological Survey of Alabama
> Tuscaloosa, Alabama, USA