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PREDENTARIES IN SAURISCHIANS



Mike Keesey said that the predentary was totally unique to Ornithischia
(and that the name Predentata was therefore particularly appropriate
for the group).

It's worth pointing out (perhaps) that some saurischians evolved a
neomorphic predentary bone - it's present in hesperornithiforms,
ichthyornithiforms and teratornithids. Its presence in the former two is
one of the characters used by Martin to unite the two in a supposedly
monophyletic clade (can't recall if he calls this Odontornithes or
Odontognathae).

While on the subject of predentaries, there are some obscure mentions
here and there in the literature of ornithischian specimens
(predominantly ankylosaurs) that supposedly lack predentaries. IIRC
these were reviewed in Greg Paul's JVP paper on segnosaur affinities.
Seeing as the predentary can drop off during decay I would suspect its
absence to be taphonomical. I've seen ornithopod specimens that are
articulated but missing the predentary, plus I don't think in-situ
predentaries are known for any pachycephalosaur (except maybe the
new Triebold spiky Sandy Site specimen?).

"Where is that shuttle going?"

DARREN NAISH
PALAEOBIOLOGY RESEARCH GROUP
School of Earth & Environmental Sciences
UNIVERSITY OF PORTSMOUTH
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