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[firstname.lastname@example.org: Amphibious sauropod renaissance?]
More from Darren, who REALLY ought to be working on his dissertation
instead of trawling the DML archives :-)
For what it's worth, Matt Bonnan's dissertation concluded that
"Statistically significant differences in limb and foot bones of
Apatosaurus, Diplodocus, and Camarasaurus suggest these
contemporaneous sauropods had differing terrain preferences. In
particular, Apatosaurus and Diplodocus appear to have been better
suited to traversing wetter sediments than Camarasaurus." So if
anything was adapted to aquatic habitats, this suggested it would have
been diplodocids. But the evidence still overwhelmingly points to
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Date: Thu, 14 Jul 2005 22:02:36 +0100
From: "Toni" <email@example.com>
To: "Mike Taylor" <firstname.lastname@example.org>
Subject: Amphibious sauropod renaissance?
Me again, clearly desperate to waste what free time I have by pissing it away
on emails about sauropods, swans and other things unrelated to my research.
- - - - [should you feel that the following is useful or interesting, please do
post it to DML]
Saw on DML your request for refs on the assertion that some workers have
recently suggested amphibious/aquatic habits for some sauropods. I think the
person who made this assertion has been reading between the lines - no one (to
my knowledge) has suggested this recently, and of course all the evidence is
against it, but a few people have >intimated< that some sauropods might still
have associated with water. Two things in particular come to mind: firstly,
there were Matt Bonnan's musings on DML about flagellicaudatan hindfeet. He
noted, in informal emails, that feet and toes are apparently more flexible than
so often stated, and I think (though I can't find an email stating such) that
he implied that maybe, after all, some sauropods could have been quite capable
of traversing marshy substrates. In agreement with this, I suppose, is work
showing that some sauropods inhabited such places - _Paralititan_ comes to mind
(Smith et al. 2001), as do the sauropods of Guimarota and the
coal-bearing parts of the Morrison Formation. Dodson (1990) and Henderson
(2003) both pointed out an association of some sauropods with moist conditions.
None of this, of course, means however that the sauropods in question were
amphibious or aquatic. I can't help thinking of moose, which spend considerable
time during certain parts of the year wading, swimming and diving (even staying
submerged for up to 6 minutes or so) and feeding on aquatic vegetation - yet I
can't recall hearing this animal described as amphibious (Geist 1999).
Secondly, and rather more explicitly, Tim Pedley and colleagues have suggested,
as a result of their work on the cardiovascular system of giraffes (Pedley et
al. 1996), that sauropods fed from aquatic or amphibious vegetation. Thomas
(1997) writes 'Pedley argues that sauropod dinosaurs could not have browsed
from the treetops ... Instead, he believes that they used their long necks to
feed off weeds growing on the bottom and rivers and lakes'. Of course, we
shouldn't really talk of scientists 'believing' in anything, and the point of
view promoted here is hardly original - but it is, pretty much as far as I
know, the only recent published suggestion promoting this view of sauropods. As
is well known, and as is pointed out in the same article, the evidence from
tooth wear and so on indicates that the sauropod taxa that have been studied in
this context did not feed on aquatic vegetation.
Refs - -
Dodson, P. 1992. Sauropod paleoecology. In Weishampel, D. B., Dodson, P. &
Osmólska, H. (eds) _The Dinosauria_ (University of California Press, Berkeley),
Geist, V. 1999. _Deer of the World_. Swan Hill Press (Shrewsbury), pp. 421.
Henderson, D. M. 2003. Tipsy punters: sauropod dinosaur pneumaticity, buoyancy
and aquatic habits. Proceedings of the Royal Society of London B 271 (Supp. 4)
Pedley, T. J., Brook, B. S. & Seymour, R. S. 1996. Blood pressure and flow rate
in the giraffe jugular vein. _Philosophical Transactions of the Royal Society
of London B_ 351, 855-866.
Smith, J. B., Lamanna, M. C., Lacovara, K. J., Dodson, P., Smith, J. R., Poole,
J. C., Giegengack, R. & Attia, Y. 2001. A giant sauropod dinosaur from an Upper
Cretaceous mangrove deposit in Egypt. _Science_ 292, 1704-1706.
Thomas, J. 1997. A heart for heights. _New Scientist_ 155 (2100), 24.
School of Earth & Environmental Sciences
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