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Re: teeth



fossils@redestb.es wrote:

>Please, can anyone tell me which are the anatomical differences among
>the teeth of crocodyles and dinosaurs?
>Are there information about it?
>Thanks in advance.
>Antoni Lacasa


Theropod teeth are (usually): slightly to strongly trenchant;
laterally-compressed (except in front-most teeth); distal cutting
edge usually serrated (exceptions in are some Mesozoic birds);
mesial cutting edge sometimes serrated; carina on mesial
surface often curves laterally moving toward base of tooth;
surface often slightly indented on lingual and labial sides
of tooth near base of tooth; pulp cavity (or resorbtion cavity)
usually deeper than similar cavities in crocs; pulp
cavity (or resorption cavity) sometimes laterally-compressed.

Croc teeth are (usually): straight to very slightly trenchant;
not laterally compressed (usually peg-like or conical);
usually two non-serrated carinae on opposite sides of
tooth; carinae commonly missing altogether;
carinae, if present, do not curve laterally moving toward
tooth base; pulp cavity (or resorbtion cavity) generally
shallow; pulp cavity circular to oval in cross-section;
croc teeth have greater width-at-base/length ratio than
theropod teeth (even in shed teeth).

North American theropod teeth possess very smooth
lingual and labial enameloid surfaces.
North American fossil crocs sometimes have fine longitudinal
ridges running all over their tooth surfaces.

Some South American theropods and some African
theropods had ridged or crenulated enameloid surfaces.
This may be a synapomorphy in those "southern groups",
for all I know....