Dinosaur diversity (was Re: paleontologist, dinosaurs...)

["Tim Williams" <T.Williams@cclru.randwick.unsw.edu.au>]

George Olshevsky wrote:

> ... just hundreds and hundreds of
> garden-variety dinosaur genera missing from the fossil record. Among these
> are Jurassic marginocephalians,

_Chaoyangosaurus_ and a few others still in the _nomina nuda_ stage.

> Jurassic-Cretaceous thescelosaurids,

Got me there...

> sauropods intermediate between camarasaur-like and diplodocus-like forms,

..and here.  Assuming these actually existed.

> Jurassic titanosaurs,

_Janenschia_ and possibly _"Apatosaurus" minimus_

> a host of spinosaurians and megalosaurs,

Spinosaurians, sure.  Megalosaurs - I've got megalosaurs of one form
or another coming out of my ears.

> pre-_Alxasaurus_ segnosaurs,

If segnosaurs (therizinosauroids) are part of the great coelurosaur
radiation of the early Cretaceous, then pre-_Alxasaurus_ segnosaurs
may be very hard to find.

> Jurassic bullatosaurs,

_Koparion_, _Palaeopteryx_ - two highly dubious troodontids I must
confess.  But there's rumour of a possible ornithomimosaur from the
Morrison (not _Elaphrosaurus_, now in the Ceratosauria).

> loads of Jurassic hypsilophodontians,

_Agilisaurus_, _Yandusaurus_, _Othnielia_, _Drinker_, ?_Nanosaurus_

> early Cretaceous tyrannosaurids,

_Siamotyrannus_.  That _Tonouchisaurus_ I've heard so much (and so
little) about.

> Gondwana dinosaurs of
> all kinds,

Here here to that!

> you name it. Not to mention about 50 million years of
> pre-_Archaeopteryx_ avians.

Hmmmm.