Re: Bakker's Brontosaurus and Late Cretaceous populations

[dinoboygraphics@aol.com]

I was at the Tate at the time these shenanigans were going on; Tim's 
summary of the of Bakker's 1998 paper basically sums up the story 
correctly, but I thought I'd throw in a few insider details. A skull 
was found by a Dinamantion customer at Nail Quarry at Como Bluff in the 
mid 9i0's. It was prepped out by Melissa Connely at the Tate, who then 
molded it and made wax casts. Those casts were heated, manipulated, and 
then remolded to make a display cast of the skull that looked less like 
it had been run over by a steam roller. Unfortunately, subsequent 
studies (a poster at Snowbird and Bob's reference in the 1998 paper) 
appear to have been done on the reconstructed cast, rather than on the 
original deformed pieces.

As many of you are probably aware, Bob has been advocating the use of 
Brontosaurus for some time now, and in the late 90's he decided that 
"Brian" (the name applied to the Tate skull) was significantly 
different from the original Apatosaurus skull to warrant generic 
separation. Without even touching on the salient issues that HP Holtz 
brought up about the capriciousness of generic distinction, this issue 
should be dead on taphonomic and systematic grounds. The skull was 
found in a quarry that contained at least 9 different individuals, and 
multiple diplodocid species. It was not articulated, or even well 
associated with any postcranial remains in the quarry (I'm pretty sure, 
as I was sitting 2 meters away when the skull was found...). The skull 
is certainly referrable to Apatosaurus sp. on morphological grounds, 
but given the dearth of comparative skull material and the lack of 
unambiguously assignable vertebrae, there is no way to confidently say 
the skull belongs to A. excelsus.  And if it can't be shown to belong 
to A. excelsus, it can't be used to resurrect Brontosaurus, even if it 
glows in the dark and has the words "I am not Apatosaurus" tattooed on 
it.

Back to work, have a great day everyone!

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(408) 483-9284

www.skeletaldrawing.com

-----Original Message-----
From: Tim Williams <twilliams_alpha@hotmail.com>
To: dinosaur@usc.edu
Sent: Tue, 02 Aug 2005 09:03:18 -0500
Subject: RE: Bakker's Brontosaurus and Late Cretaceous populations

Mike Lima wrote:

> A couple years back I had heard that Bakker considered Brontosaurus a 
valid >genus separate from Apatosaurus and had tried to find out what 
anatomical >differences he noted between the two genera but couldn't 
find anything >beyond statements to the effect of "Dr. Bakker is 
finding evidence to >support his claim that Brontosaurus is a valid 
genus." Now a couple years >later, I tried to find more on the subject 
but I'm still only finding >similar vague statements. Has Bakker ever 
published or even stated on what >grounds he distinguishes between the 
two?

In 1998, Bakker did publish a study that mentioned a skull (TATE 099) 
that he referred to _A. excelsus_. (This was in his "Dinosaur Mid-Life 
Crisis" paper, which also erected the new genus _Eobrontosaurus_ for 
_A. yahnahpin_)  He argued that the differences between TATE 099 and 
the skull of _A. ajax_ (CM 11162) were sufficient to justify generic 
separation; thus, he revived the genus _Brontosaurus_ for _excelsus_. 
However, Bakker did not actually describe the new skull, nor give 
reasons why it should be referred to _A. excelsus_ (= Bakker's 
_Brontosaurus excelsus_). I haven't seen or heard anything more on 
this.

Cheers

Tim