Re: Berlin Brachiosaurus

[don ohmes <d_ohmes@yahoo.com>]

Mike wrote: "By the way, I've always been puzzled by Henderson's conclusion that
floating sauropods would be unstable, since all the pneumatic
structures are concentrated along the (dorsally positioned) axial
skeleton while the appendicular skeleton is good and solid.  Naively,
they look to be perfectly built for stability in water."

What Mike said... states my feelings well, and very diplomatically, which is 
good. In the animation (there is a link in Kent Steven's post), the virtual 
beast is shown as head held high. Perhaps if it were to lower its head like a 
sensible thing, CG might move lower, and it would no longer be an obligate side 
or back stroker... no information on the assumptions re lung inflation. I guess 
that is in Proc B.

Also; as large as they were, sauro's could probably hold their breath for a 
_LONG_ time, even w/out diving adaptations (or lungs inflated to maximum). Add 
in assumptions about pneumaticity and metabolism, and they may be in whale 
territory or (way) beyond, dive time wise. There are obvious implications for 
long necks and resource acquisition. I point this out once again because as far 
as I know, it has never been taken into account in the now "resolved" aquatic 
vs terrestrial lifestyle debate.

Personally, I find the 'if you weighed a gazillion tons you wouldn't get out of 
the tub much either' model resonates.

Don

----- Original Message ----
From: Mike Taylor <mike@indexdata.com>
To: marksabercat@yahoo.com
Cc: Danvarner@aol.com; dinosaur@usc.edu
Sent: Monday, April 2, 2007 5:36:03 AM
Subject: Re: Berlin Brachiosaurus

Mark Hallett writes:
 > A nice short article, but where did the author get the
 > pronouncement that brachiosaurids couldn't swim? 

My best guess would be that this idea comes from the observation that
the _B. brancai_ holotype HMN SII was found in an unusual position,
its legs vertical, indiating that it died when it became mired.

Dann Pigdon writes:
 > A paper a few years ago attempted to look at brachiosaur bouyancy,
 > and concluded that their relatively narrow bodies and their
 > top-heaviness may have made them too unstable (and prone to
 > capsizing) for them to swim in open water.

Actually, there were two independent studies on sauropod buoyancy,
which happened to come out very close together:

    Henderson, Donald M.  2003.  Tipsy punters: sauropod
    dinosaur pneumaticity, bouyancy and aquatic habits.
    Proceedings of the Royal Society of London, B
    (Supplement) 271: 180-183.  DOI
    10.10998/rsbl.2003.01.36

    Wilson, Jeffrey A, and Daniel Fisher. 2003.  Are
    manus-only sauropod trackways evidence of swimming,
    sinking, or wading?  Journal of Vertebrate
    Paleontology 23(3): 111A.

Of these, Wilson and Fisher's work is still available only as that
abstract, so far as I know.  Henderson's abstract in the same volume
("Sauropod dinosaurs were the colossal corks of the Mesozoic") is
superseded by the Proc. B paper.

By the way, I've always been puzzled by Henderson's conclusion that
floating sauropods would be unstable, since all the pneumatic
structures are concentrated along the (dorsally positioned) axial
skeleton while the appendicular skeleton is good and solid.  Naively,
they look to be perfectly built for stability in water.

 _/|_     ___________________________________________________________________
/o ) \/  Mike Taylor    <mike@indexdata.com>    http://www.miketaylor.org.uk
)_v__/\  If two decades of commercial programming have taught me anything,
     it's NEVER to trust dual CPUs, "uninterruptible" power supplies
     or RAID disks.