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Re: What ever happened to Deinodon?
Gadzooks, where do I start...?
Well, these are my views on the subjects you raised.
The reclassification of _Tyrannosaurus_, _Ornithosuchus_, and the
redefinition of Coelurosauria and Carnosauria occurred simply because
the methods of classification changed. Instead of basing
classifications around the overall size and shape of dinosaurs,
paleontologists began looking at the more subtle details of dinosaur
anatomy - arrangement of the bones that make up the braincase, shape
of the limb and hip bones, position and number of fossae in the
cranial elements, things like that. Most of these characters are
extremely esoteric, and are little perplexing to amateur
paleontologists (like me - I've only just worked out what an
obturator notch is). And, I suspect, they're a headache for serious
paleos too. But they give a much more accurate view of dinosaur
Hence, _Ornithosuchus_ was shown not to be a dinosaur at all. But
it lies somewhere not too far from the origin of the Dinosauria. A
group was created to accommodate ornithosuchids, "lagosuchids",
dinosaurs and pterosaurs, and this group was called the
Ornithosuchia. The Ornithosuchia did not replace the Pseudosuchia;
both were just redefined. Same goes for the Coelurosauria and
So too, a closer look at tyrannosaur anatomy led many paleontologists
to believe that they were really more closely related to groups like
the troodontids and ornithomimids, not to other big theropods like the
megalosaurids and allosaurids.
_Deinodon_ is a pretty shoddy genus since it's based on lousy
material (a few teeth I believe). It was not possible to define
_Deinodon_ as a distinct genus, since (from what is know of it),
_Deinodon_ has no unique features that could distinguish it from
genera like _Albertosaurus_ or _Gorgosaurus_. Hence, _Deinodon
horridus_ is best regarded as a _Nomen dubium_ (dubious name). And,
since you cannot name families after _nomina dubia_, the name
Deinodontidae is defunct. Tyrannosauridae wins out.
(Yes, yes, I know the Ceratopsidae, Hadrosauridae, and possibly the
Titanosauridae are all named after genera based on indeterminate
material, but that's another can of worms I don't really want to
Some generic names replace other generic names (like the
_Apatosaurus_ and _Brontosaurus_ story), because when two genera are
found to be the same (like when the material on which genus is based
is found to be more-or-less identical), the genus that was named
first takes priority, and the other genus is relegated to a junior
synonym. _Brontosaurus_ (alas) was sunk as a junior synonym of
_Antrodemus_ was named before _Allosaurus_, but the former is a
_nomen dubium_. _Antrodemus valens_ was based on an incomplete
tailbone which could belong to _Allosaurus_, but it could also belong
to a number of other big theropods. Hence, _Antrodemus_ gets
consigned to the taxonomic wastebasket. Here it can join
_Deinodon_, _Trachodon_, _Ceratops_, and a host of other dinosaur
genera based on indeterminate remains.
Hope that helps.