Re: ANKYLOSAURS THE MOVIE

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

D.W., thank you for your concise summary.

>3) Minmi paravertebra is restored in Dave Lambert's 'The Ultimate Dinosaur
>Book' AND it's been given lateral caudal spikes... I said that these were
>unique to polacanthids. Three options;
>i) Minmi is polacanthid (unlikely me thinks)
>ii) The restoration is innaccurate (I haven't seen any good specimens of the
>type or the paper describing it)
>iii) Big, lateral, caudal spikes are not unique to polacanthids

The latter, I think, although the other two are certainly possible.
Polacanthids also have sacral shields, and a few other characters I can't
remember at the moment.

>I am unaware of the study proving that Hylaeosaurus and Polacanthus are
>distinct. I thought that the consensus was that both were known from different
>parts of the skeletons, and thus couldn't be adequately compared. As I said, I
>have heard suspicions that the shoulder spines were orientated differently in
>the two though...

William Blow and Javier (now Xabier) Pereda-Suberbiola both have published
papers to this effect.  I'll try and find the refs.  Also, from what I know
of the new Polacanthus specimen(s), there is enough to show that
Polacanthus and Hylaeosaurus are distinct.  (Incidentally, the synonomy of
Dyoplosaurus and Euoplocephalus is not as set as it has seemed in recent
decades, or so some anky wokers tell me...)

>If they were the same (and we seem to be agreeing that they're not) then
>Hylaeosaurus would have priority as it was named by Mantell in 1833.

An aside - Hylaeosaurus is, of course, the often forgotten third member of
Owen's original 1842 Dinosauria (the others being Iguanodon and
Megalosaurus).

>On an interesting
>diversion, the family Tyrannosauridae should really be called Deinodontidae for
>the same reason, and likewise Dinosauria should be called Pachypoda. But
>there's
>some rule stating that when a name becomes so forgotten and superseded by a
>more
>popular term, it can be forgotten. Who knows what the rule is?

In the case of Tyrannosauridae-Deinodontidae: a) the former is a much
cooler name, and b) Deindon cannot be confidentally associated with either
Albertosaurus/Gorgosaurus or Daspletosaurus (the two Judith River
tyrannosaurids known from skeletons, so we don't really know what
"Deinodon" is.

In the case of Pachypoda: the rules of priority are much less strict for
suprafamilial taxa.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.