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Re: Diplodocus: Return to the Swamps????
--- On Mon, 12/14/09, David Marjanovic <firstname.lastname@example.org> wrote:
> From: David Marjanovic <email@example.com>
> Subject: Re: Diplodocus: Return to the Swamps????
> To: "DML" <firstname.lastname@example.org>
> Date: Monday, December 14, 2009, 6:23 AM
> > Sounds like a buffet for
> Exactly. If you're in a swamp and can't move quickly, the
> crocodiles will eat you alive. Goniopholidids had cutting
> edges on their teeth. None of this death roll business --
> they could just come in and take a bite.
Obviously, hippos will be extinct soon. Elephants in swampy areas, too. Oh well
, easy come, easy go...
Anyhow, the croc aspect of swamp living having been largely dealt with
previously, I will post an answer now (see below). Relative vs absolute power
(also previously covered) will be combined w/ thoughts about the appearance in
the geo-record of vertical limb elements and dry-land sauropod death at a later
time . This is another (very) long post, so chopped text will be "repaired" in
a subsequent post...
The image of a lone mud-constrained giant covered by ant-like swarms of
knife-toothed croc-types isn't likely a realistic scenario in a swamp. Crocs
are ambush predators, and therefore do not populate the homogenous areas
covered by swamps as densely as they do natural nick-points like those sections
of rivers and lakes used as waterholes by the denizens of large swathes of
terrestrial habitat. Scenes of lone sauropods attacked on slippery waterhole
approaches by ant-like swarms of highly cursorial bipedal saw-toothed
land-sharks equipped w/ claws that might be useful for climbing columnar legs
and flanks seem more compelling. Not to mention attacks by packs of allosaurids
w/ great balance and traction :)...
Assuming an adult sauropod is in mud so deep that the base of the neck at the
water/mud surface, they would be quite vulnerable to croc attack, especially if
the head was also at that level. In shallower situations, it is the croc that
is tactically vulnerable, mostly to stomping, especial
here groups* of sauropods are involved. Obviously, there is an advantage to
tallness and therefore size in this case, and therefore another potential
vector for directional selection to giant-ism.
Note that putative swampy refugia are likely to be tree-free in areas
(particularly after thorough tromping by generations of sauropods), and
therefore ideal for the much-dreaded surface-skimming tail-sweeps**, as opposed
to terrestrial environments, where serious injury to hypothetically super-sonic
tail-parts seems near-certain.
Also, a well-trodden bottom laced w/ the bones of over-bold predators and
compacted vegetative material would offer the hind legs an excellent platform
from which to launch a counter-attack w/ the relatively compact front feet. In
the case where a bottom cannot be touched by the would-be predator, and the
long neck is hard to ambush due to elevation, the tactical advantage of the
sauropod would be overwhelming, even in the crocodile case.
Areas where even the long legs of sauropods cannot find a bottom might be
avoided by sauropods, and therefore controlled by croc-types, but even that
does not seem like a sure thing, given sauropod size, and their ability to
alter the environment to their advantage. I think a 'sauropods move in, crocs
move out' scenario or 'live and let live' would be the better guesses in most
Watching the familiar video of the gigantic croc(s) attacking the flanks of
migrating wildebeests gives the impression that even w/ those relatively small
herbivores, attack success is hardly guaranteed. Further, breaking a sauropod
into bite-size chunks might prove to be somewhat troublesome, even for
Deinosuchus. Smaller saw-toothed predators might have trouble w/ sauro-hide. No
doubt those are possibilities, though.
In other words, rather than certain croc-related sauropod death, I think the
croc/sauropod relationship could be assumed to follow the modern hippo/elephant
vs croc model, wherein the large herbivores apparently access croc-infested
arily (any references to the contrary appreciated).
*herds? gaggles? flocks? I like 'gaggle' relative to sauropods...
**perhaps even a downward-directed modified overhead smash? Again, a maneuver
that seems certain to cause tail injury in terrestrial environments.