Re: Extinction - specific info

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

>Great list of latest Maastrichtian dinosaurs.  This will be helpful (now
>Norm needs some ranges in esp. Hell Creek).

Hopefully someone can get those ranges together.  Most of the biostrat-type
research on dinosaurs is currently in the Judith River, but maybe we can
convince them to get further up in the section.

>I would be very interested in your opinion of the following (especially
>the genera) which are listed by Weishampel 1992(in Weishampel a.o. The
>Dinosauria) as being of late Maastrichtian of North America but not in
>your list.  (Page of citation given.)
>
>cf. Chirosenotes sp.  p. 115

This is the "Elmisaurid indet." of my listing.  Elmisaurid systematics are
a little problematic at the moment, so hopefully Hans-Dieter Sues can sort
this out.

>?Caenagnathus sp.  p. 115

Caenagnathids are known only from jaws, and I know of none from the Lancian
(all the North Ameican ones are from the Judith River).  But, caenagnathids
(known only from dentaries) may be elmisaurids (this is Sues' project I
just mentioned above).

>Sauornitholestes sp.  p115

This is my "Velociraptorine indet."  Saurornitholestes may be the same
genus as the Asian Velociraptor.

>Montanoceratops cerorhynchus  p. 117

Last I heard, Montanoceratops was Edmontonian.  I'll check on this.

>Avisaurus archibaldi  p. 117

Avisaurus is an enantiornithine bird (Chiappe, L. M.  1992.  JVP 12(3):
344-350.)

>?Dryptosaurus sp. p 119
>?Lambeosaurus sp.  p. 119
>cf. Struthiomimus sp. p 121
>?Gryposaurus sp.  p. 123

I don't have my copy of Weishampel et al. with me at the moment (nor can I
find the library's copy), but these sound like they may be East Coast
specimens by their page numbers.  The East Coast dinosaurs are poorly
constrained taxonomically (only Dryptosaurus aquilunguis is defintely
distinct from any western taxon).  Furthermore, many of these specimens are
poorly constrained stratigraphically, although they have the potential to
be very well dated, given a pretty-well understood Coastal Plain
stratigraphy.  The best East Coast Late K dinosaur fossils are probably
late Campanian.

>I realize many of these are probably = to some of the genera you
>recognize, but I would be interested if any of these 9 genera might
>increase the number of genera recognized.

Hmm, let's see... Even if you lump as far as you can (put both
dromaeosaurids as one genus, all the tyrannosaurids as one, take out
Dyslocosaurus, put all the Triceratops line [D. hatcheri, T. horridus, and
T. sp. 2] as one, both Thescelosaurus forms together, and Anatotitan into
Edmontosaurus [although it is clearly a very derived form]), you've still
got 17 valid genera.  And that's just North America...

                                
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.