RE: PARTICULAR sauropods aquatic?

["Thom Holmes" <tholmes@dolphinsoft.com>]

One of the most accessible volumes for the general and semi-technical reader
covering the problems of the underwater sauropod and other physiological
feats of dinosaurs is "Dynamics of Dinosaurs and Other Extinct Giants" by
R. McNeill Alexander / Paperback / Published 1991. He covers the dynamics of
speed, rearing-up of sauropods, and other matters that are often discussed
on this list. His citations will lead you to many of the original sources of
these ideas. This is the book that includes his famous formula for
calculating dinosaur speed from trackways.

--Thom Holmes
dinosaur author at large

-----Original Message-----
From: Matthew Bonnan [mailto:mbonnan@hotmail.com]
Sent: Thursday, September 02, 1999 12:29 PM
To: dinosaur@usc.edu
Subject: re: PARTICULAR sauropods aquatic?


Boy, you folks sure know how to set out the fly paper for me!  Feet and
sauropods: that bait works quite well! =)

I don't have much time right now, but let me throw a few things out there.
First, Riggs back in the early 1900s was the first paleontologist to put
down in writing the idea that sauropods were terrestrial, this based in part
on the morphology of feet which are more like those of terrestrial mammals
than aquatic or semi-aquatic mammals.  He also noted that some sauropods may
have reared up on their hind legs.  Later, Bakker (1971) and Coombs (1975)
recapitulated his ideas and revived the notion of terrestrial sauropods,
this coming quickly on the heals of Ostrom's observations that perhaps some
dinosaurs were endothermic.

I believe it was Kermac (195?) who showed that the pressure from water on
sauropod lungs would have caused problems for the animals if they habitually
were completely submerged.  Comparing sauropods to whales is very
problematic, not the least of which is the fact that whales habitually dive
to great depths and have many special adaptations for this that were
probably absent in sauropods.  I do not know how far the "blowhole" is from
the lungs in cetaceans, but my guess is that this is shorter than the head
to lung distance encountered in most sauropods.

Studies by Peter Dodson et al. in the 1980s and continued since by other
researchers have shown that sauropods are found in many different
environments ranging from dry, terrestrial to relatively moist.  Personally,
I have no problem with sauropods wading into water and even feeding there at
times.  However, completely submerged sauropods would seem to be impossible
based on the laws of physics as we understand them.

The huge morphological difference in the forefoot (manus) and hindfoot (pes)
of sauropods sets them apart from elephants which have feet both fore and
aft that are of similar construction.  The columnar, ring-like structure of
the metacarpals in sauropods is very interesting and bizarre, even when
compared to other saurischian dinosaurs.  The phalanges are pretty much an
after thought in the manus, and it has been suggested that their absence in
titanosaurs is real (Wilson and Sereno, 1998) and that they never ossified
in some sauropods.  The big pollex claw ... that's for when I have more time
to write!

Lastly, juvenile sauropods which were aquatic while they had terrestrial
parents would seem to be problematic.  Sauropods must have had big appetites
and may have migrated to satisfy their hunger.  How would the aquatic or
semi-aquatic juveniles have following the land-lubbing adults?

As I'm sure this thread will continue, more info when I have more time.

Alright, more sauropod feet!

Matt Bonnan

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