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Re: Theropod Teeth/Lizard lips



>        There may have been room for a little variety here.  Some modern
>crocodilians have exposed teeth when their mouths are closed, others do
>not.

All crocodilian have exposed teeth wehn their mouths are closed. Some
crocodilians (alligaotors and caimen) have some teeth hidden when their
mouth is closed. None have lips to conceal their teeth.

>Since predatory
>dinos had dentition that more closely resembles crocodilians' than it does
>other modern predators', as far as natural selection goes the overbite may
>not have been a big deal.

In crocodilians and predatory dinosaurs with an overbite dentition, the two
sets of teeth work against each other like a pair of scissors. The
"cooky-cutter" analogy would more appropriately be expressed as a "pair of
cooky-cutters", one slightly smaller than the other. Where an overbite is
present, it is a big deal: the slicing action of the jaw can not function
if there is no overbite. It is probably also important that the action of a
double cookie-cutter gob not be impeded by the presence of superfulous
lips.

Cheers, Paul


Dr Paul M.A. Willis
Consulting Vertebrate Palaeontologist
Quinkana Pty Ltd
pwillis@ozemail.com.au