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Re: Bakker's Brontosaurus and Late Cretaceous populations

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


-----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.