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Re: Sauropod necks????
Other reasons for "liking" a retro hypothesis:
1. Alligators can stay under water for 2 hours.
Achievable dive time increases with body mass. Perhaps
sauropods couldn't breath while mostly submerged like
hippos, but they may have only needed to "surface" 3
or 4 times a day. Another positive selective vector
relative to size.
2. A sauropod standing in water at a depth such that
the base of the neck is at the surface of the water
could be able to (at least) partially inflate it's
lungs. If the neck is then "floated", a large arc of
water column could be foraged at low cost and the
nostril position is (finally!) clearly advantageous.
3. Given the length of their legs, and their
presumable power, they may have been difficult to bog
down, even when fully emerged from water. Given mud
overlain by shallow water, they may have gained some
locomotive advantage from the long neck and tail
(rocking side-to-side, increased "flotation", and
forward momentum from the tail).
--- don ohmes <email@example.com> wrote:
> Finally someone responds to this (thanks, David):
> You are in line with concensus thought on this.
> However, current research indicates an earlier
> for angiosperms (as early as ~340 mys BP, in my
> readings), and there is literature discussing an
> aquatic origin of same. So as an old farm boy who
> spent many hot days acquiring biomass, I am willing
> reconsider a retro hypothesis, even though it might
> a stretch.
> You see, I, like the individual who supposedly
> invented the hypothetical shell-less molluscs (from
> Colbert, if memory serves) have a hard time squaring
> the probable daily amounts of forage the largest
> sauropods required (assuming mass specific
> values have not changed) with the physical equipment
> they had to work with.
> "Facts"? In os veritas. The rest is best guesses,
> --- David Marjanovic <firstname.lastname@example.org>
> > ----- Original Message -----
> > From: "don ohmes" <email@example.com>
> > Sent: Sunday, May 22, 2005 12:13 AM
> > > I like the idea of hydrilla or some aquatic weed
> > with
> > > similar interwined growth habit as a primary
> > > source. [...]
> > >
> > > Hydrilla seems to grow best in water 1-2 m deep,
> > and
> > > will utilize every cc of water column. So no
> > to
> > > move tree to tree, hold the head up, pull back
> > > strip leaves, or separate/swallow twigs, just
> > > through it like a teenager sucking up a giant
> > plate of
> > > spagetti. Only practical way I see to obtain the
> > truly
> > > incredible bulk the biggest probably needed. Any
> > > thoughts?
> > Several.
> > - *Hydrilla* and most other water weeds are
> > angiosperms, and thus
> > unavailable in the Jurassic. I don't know enough
> > about ferns like
> > *Salvinia*, but AFAIK they don't get this
> > productive...
> > - So much water may not have been available in,
> > example, the Morrison Fm
> > environment.
> > - The neck length of *Dicraeosaurus* should
> > for this lifestyle. So
> > why do sauropods vary so much in neck length?
> > Beautiful hypothesis, ugly facts... :-]