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Re: Globidentines

Richard Ellis cited (12/4/99; 8:16am) this passage:

>SEILACHER, A. 1998. Mosasaurs, limpets, or diagenesis. Geowissenschaftliche

In the German journal Geowissenschaftliche Reihe, Adolf Seilacher (1999)
wrote, "The claimed 'mosasaur bites' are probably all caused by limpets
rasping on necroplanktonic Placenticeras shells, compactual puncturing of
the pits and diagnostic beveling of the rims." In other words, the ammonites
were already dead and lying on the bottom when they were colonized by the
limpets. Furthermore, the experimenters built a machine fitted with
artifical mosasaur teeth, and when they applied it to freshly-caught
nautilus shells with the equivalent pressure of mosasaur bites, it shattered
the shells instead of puncturing them. <

I am having trouble with the lining up of the punctures if they are limpet
holes, and also with the smooth increase in separation of the lines of
puncture marks, if they are indeed limpet borings.  I am also having trouble
with the same pattern showing up on more than one ammonite specimen, and
matching the size range of mosasaur jaws.

Why would limpets rasp or bore holes into empty shells, and why in linear

How do we know that when mosasaurs caught ammonites, they bit into the
shells with full force?  Would ammonite shells react the same way to such
bites as Nautilus shells, with the extremely complex suture pattern of
Placenticeras compared to the straight sutures of Nautilus?  Did the
Nautilus shells have living Nautilus in them when they were bit by the
machine?  Was the experiment performed under water?  

Maybe the reason we haven't found Nautilus shells with mosasaur bites is
because when mosasaurs bit Nautilus shells they shattered them, just as the
above results predict.

I don't have access to that journal except by interlibrary loan.  Maybe
Seilacher addressed some of these points, but I don't think the issue is
settled yet.