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Re: Dinosaur Genera List corrections #98
On Thu, 5 Nov 1998, Allan Edels wrote:
> Bakker had a cast of the skull and the left lower jaw with him at
> DinoFest 1998. I was there when he first showed the skull to Jack McIntosh
> and Dong Zhiming. (In fact, I was holding the jaw for him while he was
> showing the braincase to Jack).
> Jack McIntosh's INITIAL view was that the braincase was _significantly_
> different than _Apatosaurus_. Bakker's initial idea was to resurrect
> _Brontosaurus_ based on this reconstructed skull (due to be so much
> different than _Apatosaurus_).
> One cautionary note, the skull was reconstructed using a wax casting of
> the original, which was then stretched to what was considered the proper
Having been on site when the skull was found, and present during much
of the preperatory and reconstruction process, I have a few choice words
about Eobrontosaurus. First of all, Eobrontosaursus was not created for
the skull that has been displayed. It is for the animal described
intially as Apatosaurus yanahpin (pronounced wah-nah-pae). By Filla et
al. I'll get back to that momentarilly. First, Bob still wants (as of
three months ago) to resurrect Apatosaurus for the skull that Allan is
refering to. The skull came from the Tate Museum's "nail" quarry. It's
not directly associated with any other material, although there is some
other unidentified diplodocid material from other parts of the quarry.
The presence of multiple ontogenetic stages for the diplodocids, as well
as 7+ other taxa in the quarry make association of the skull with
anything. Certainly there is no type Brontosaurus skull with which to
compare this new one to. To make things worse, the skull is
stratigraphically higher inthe ection than the original "Brontosaurs"
material. Brontosaurus is a fine generic name, but it's dead. AS to the
comment on wax reconstruction...
Melissa Connely of the Tate Museum was in charge of reconstructing
the skull. The skull is over 90 percent complete, and let me say that
when it is properly described, there will finally be some really good
cranial syanpomorphies we can use to identify apatosaurine diplodocids.
Due to diagenetic crushing, reconstruction of the maxillas was required in
order to produce a displayable (read: profitable) cast that was closer in
appearance to real life. Wax casts were made of the left maxilla
and the palatines. These were then heated, and while still
pliable, tweaked to match other specimens or, when available, the uncrushed
mirror element. Ignoring the protestations of myself and a few others,
Mrs. Connely has taken this version with her to professional conferences
(including SVP). While I believe this to a lapse in judegement, the
braincase has never been (to my knowledge) exposed to this type of
treatement, and the cast of that element shown to McIntosh was an accurate
representation of the skull. What is it? Possibly dimorphism. Heck,
maybe it's Barosaurus. It does look like a new taxa, although, as
mentioned above, certainly not Brontosaurus.
Back to Eobrontosaurus. As mentioned, this new generic name is to be
given to A. yahnahpin. Although skulless, this taxon is probably going to
be valid. It's much lower in the section, and has many primitive traits.
For those of you who have copies of Hunteria, look at the scapula again.
Now imagine similarily primitive features in the dorsal series, tibia
fibula comples, and sacrum.
A quick note to paleoartists who may want to restore
"Eobrontosaurus." Ignore the illustration in the Filla's paper that's
supposed to be a reconstruction of the animals dorsal series, ribs,
xiphisternum, and gartalia series. Although the illustrations of the
gastralia are accurate, the rest of the illustration was simply patterned
after a picture of Bob's. Most of the dorsal series hadn't even been
fully excavated at the time. Filla and Pat Redmen have both told me that
the illustration was supposed to be a diagramatic representation
demonstrating their interpretation of the relative postition of the
gastralia compared with the other elements. Regardless, the figure was
not labeled as such, and at least three artists I know haw based
reconstructions upon it.