[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: sauropod necks-buckaroobwana is back! ha ha ha ha ha !!
Matthew Bonnan wrote:
> Buckaroobwana said:
> >This has probably been discussed before, but could sauropods raise their
> >necks up into a vertical position?
Scan the archives for: "DIGITIZED SAUROPODS" (Sept. '97), NECKS AND REARING"
(Oct. '97), "Mamenchisaurus neck" (Jan. '98), "Sauropod Neck Motion" (Sept.
'98), "Sauropod neck positions" (Feb. '98), "Bipedal apatosaurs and stegosaurs"
(Oct. '96), "Re: Lost World sauropod" (May '97). There has been a lot of
discussion on this subject. See also November '97 _Discover_ and see
<www.nationalgeographic.com/dinorama> and associated links.
> ... the
> downward flexibility of the neck in diplodocids is extraordinary. This
> suggested to Parrish and Stevens that diplodocids may have been grazers.
... although this downward flexibility is also compatible with the "tripodal
feeding posture" hypothesis for sauropods, which would explain why diplodocid
teeth don't show the wear expected of grit munching cows. (See archives for
> Brachiosaurus did have a relatively vertical neck, but not as tightly kinked
> a one as you see in most illustrations (e.g., Greg Paul's Brachio herd or
> muscle restoration pics show the neck much too vertical -- in those
> positions, the vertebrae are literally disarticulated from one another --
> just an example, not to pick on Greg Paul who, in my opinion, is a fantastic
> dinosaur artist).
If you've seen Bob Morales' _Brachiosaurus_ sculpture, or the _Brachiosaurus_
restoration by Gregory S. Paul which served as a model for Morales' piece, you
will see that Paul has changed his interpretation of the neck. Paul (and
Morales) portray a high neck, which is less than vertical, something like a
giraffe's neck, considerably higher than the restoration on page 132 in Czerkas'
and Czerkas' _Dinosaurs: A Global View_. The neck is for the most part
straight, in contrast to Paul's earlier s-curved "swan" necks. The illustration
and drawing have been seen in _Prehistoric Times_ and, I believe, can be seen at
the "Dinosaur Art and Modeling" web site. I have the model, which I have yet to
assemble, and, in my unbiased opinion, it is a marvelous piece of work.
> As far as endothermy/ectothermy in sauropods, well, who knows?
Very controversial, and not a settled question at all. Would an endothermic
sauropod self-immolate? ;^) Sauropods may have shed body heat via the long
tail and neck, which were relatively high in surface area and low in volume, as
others have pointed out. A problem with the lifelong ectothermic sauropod model
is that it would take years for the tiny hatchling to develop great size,
especially if it grew at a slow rate! Mass homeothermy thus would not be
operational at the outset, and a slow growth rate would imply an incredibly long
life span. It is probable that different dinosaurs had different metabolic
levels and regimes, and that these levels varied through the life span,
especially in the giants. At the risk of stating the obvious, I would point out
that there is much variety in the physiologies of extant animals. R. McNeill
Alexander's _Dynamics of Dinosaurs and other Extinct Giants_ discusses some of
-- Ralph W. Miller III firstname.lastname@example.org