Re: Judith/Two Med/Horseshoe fauna

["Nicholas J. Pharris" <pharrinj@PLU.edu>]

On Wed, 24 Jan 1996, Jeffrey Martz wrote:

Just to clear the record:

 
> Correct me about the following:

Gladly.
 
> ALBERTOSAURUS:  The once accepted species have been reassigned as follows:
> 
> Albertosaurus libratus: THE TYPE (AMNH, 5458 Judith River Formation) IS NOW 
> BACK TO GORGOSAURUS LIBRATUS, A LARGE TOOTHED ALBERTOSAURID LIKE 
> DASPLETOSAURUS.  
> ALL OTHER specimens attributed to A.libratus ARE ALSO LARGE TOOTHED 
> ALBERTOSAURS NOW FLOATING OUT IN TAXONIOMIC SPACE SOMEWHERE (Pharrinj 
> suggests assigning them to Dinotyrannus)

Hold on, there.  The type of the species _libratus_ (NMC 2120) does probably 
belong in its own genus, _Gorgosaurus_, ALONG WITH SEVERAL OTHER SPECIMENS, 
including TMP 85.62.1 and AMNH 5458.  

I didn't know much about _Dinotyrannus_ when I started this, but I now know 
that _megagracilis_ specimens are the only ones assignable to that genus.

      
> Albertosaurus sternbergi: (AMNH 5664, FMNH PR308) Considered a juvinile of 
> "A.libratus" be Paul (1988): NOW GORGOSAURUS STERNBERGI.

Quite likely a juvenile of "Albertogorgon," as mentioned below, but 
possibly a different species (including AMNH 5664 but NOT FMNH PR308).


> Albertosaurus arctunguis: (Horseshoe Canyon) ALSO DUMPED FROM 
> ALBERTOSAURUS AND NOT REASSIGNED? Pharrinj suggests assigning these to 
> Dinotyrannus as well.  Are these now under Gorgosaurus arctunguis 
> TMP 81.10.1?

Dinogeorge considers it referable to _Albertosaurus sarcophagus_.  

If the partial skull and skeleton TMP 81.10.1 is referable to this species as 
suggested by Paul (by no means certain) and if the skull is restored 
correctly in PDW, I consider it another species of _Gorgosaurus_.  
Philip Currie is considering the possibility that TMP 81.10.1 is 
referable to _Daspletosaurus_ (not impossible, but it looks rather long 
in the snout for this).  

One thing 81.10.1 is NOT is 
_Dinotyrannus_ (sorry for the confusion).  About the type specimen I know 
nothing except that it is poorly preserved and comes from Horseshoe Canyon.

The specific name is _arctunguis_:  Latin "arctus" = narrow, "unguis" = 
claw, hoof.
 

> Albertosaurus megagracilis: (Hell Creek Formation) Now assigned its own 
> genus, DINOTYRANNUS

This animal apparently belongs in its own genus, _Dinotyrannus_, and is 
apparently related to _Tyrannosaurus_ rather than _Albertosaurus_.


> "Gorgosaurus libratus". Alias: "Albertogorgon lambei" (a la Pharrinj), 
> "Big toothed gorgo" (a la Bakker).  Includes "Gorgosaurus" sternbergi 
> (according to Pharrinj).  Dinogeorge suggests affinities to Gorgosaurus 
> libratus:  A NEW GENUS OF TYRANNOSAUR?  A NEW 
> SPECIES OF ALBERTOSAURUS?  HOW MANY SPECIMENS?  WHERE DOES IT COME FROM?
> WAS THIS THING UNDER A. LIBRATUS? WHAT THE HELL IS THIS THING?
 
Philip Currie and Bob Bakker are working on a paper describing this 
thing, so it will undoubtedly be named something else by the time I am in 
any position to write anything on the subject.

It is a new genus, possibly a weird, primitive albertosaurin.  The 
species _sternbergi_ is definitely referable to this genus, although I am 
not completely sure whether it is the same species as the larger type.

Apparently, many tyrannosaur specimens were collected from Judith River 
and thrown together in _Gorgosaurus libratus_ without a very in-depth 
examination of their cranial architecture.

According to Paul (1988), referred specimens most likely include FMNH PR308, 
AMNH 5336 (adults), USNM 12814, AMNH 5664, ROM 1247 (probably juveniles).

> Albertosaurus sarcophagus:  STILL VALID 
> (Judith River Group &
>  Horseshoe Canyon Formation)

Valid, but difficult to diagnose due to poor preservation.  New material 
found in Horseshoe Canyon by Currie and co. will probably help clear 
things up.

BTW, only one specimen is definitely referable to this species as of this 
writing:  the type, NMC 6500, from the Horseshoe Canyon Formation.  No 
_sarcophagus_ in Judith River.

 
> DASPLETOSAURUS TOROSUS: STILL HUNKY-DORY?

Valid species, unless you're Tom Carr; also valid genus, unless you're 
Greg Paul.  The albertosaurin answer to _Tyrannosaurus_.

 
> BAKKER'S "STRETCH SNOUTED DASPLETOSAUR": What is  THIS?

Beats me.  I've been wondering, too.
 
> This is a big mess that I would like soemone to clear up for me, please.
> Has anyone published anything on this yet?  Could someone give me the 
> reference?  
>     I'm getting all this from the "Albertosaur Systematics" thing on Jeff 
> Polings Home Page.  
> 
> LN Jeff

Hope this helped.

Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447
(206)535-8204
PharriNJ@PLU.edu