Re: [dinosaur] Fwd: Re: T. rex hunting Alamosaurus

[Dann Pigdon <dannj@alphalink.com.au>]

I'm struggling to think of a modern R-strategist that makes a highly visible 
and recognisable nest that 
doesn't protect it in some way, even if they abandon the hatchlings soon after 
birth. Those species that 
abandon their eggs as soon as they're laid tend to go to great pains to hide 
the nest, making the location 
of the eggs as inconspicuous as possible. Somehow I can't see a sauropod being 
able to do that. It's not 
like they had the luxury of flying to remote predator-free islands.

Dr Paul makes an excellent point though, about what would have happened to 
surrounding vegetation if a 
large colony of sauropods remained in one area for any length of time. Perhaps 
adult sauropods built up 
extra fat before breeding, and fasted while guarding their nests? Or perhaps 
only a few sauropods 
remained behind to protect the nest colony, while most of them moved on? Creche 
behaviour is known in 
both ostriches and caimans (albeit towards hatchlings rather than nests), which 
is a pretty good extant 
phylogenetic bracket for dinosaurs. :-)

--
Dann Pigdon

On Tue, Jul 2nd, 2019 at 11:45 PM, John Bois <mjohn.bois@gmail.com> wrote:

> We don't know how the sauropods managed their reproductive effort. Strong
> arguments benefit both sides: did they lay and leave, like sea turtles; or,
> did they at least guard their nests like gators?
> I think that if you come from stock who apply parental advantage to their
> offspring, and that your offspring are delectable to many predators, that
> you also would want to intervene in that direction. Certainly, your qualms
> are valid. Just as a thought experiment, let us say that they _did_ guard
> their nests, how could they do that without either starving or destroying
> the surrounding habitat.
> Penguin model: send off your parental partner to feed while you guard. When
> your partner returns, you go off and your significant other guards your
> babies.
> Emu model: store energy and water and go into extended, low-energy mode.
> Don't eat for weeks at a time. Pee crystalized uric acid to conserve your
> water!
> Cicada model: don't reproduce every year. This will give the producers time
> to recover and trick your predators.
> The problem for you as a sauropod, is that your eggs represent a
> concentrated resource to your predators. If you are colonial (check), you
> return to the same nest sites (check), and you cannot hide or lay remotely
> (check, check), you are in a bind. When your babies hatch, they can
> disburse, hide, etc. and enjoy some relative security.
> Re predation on adults: I agree with Dr. Habib on this. Perhaps ostriches
> are a good model...predation on adults is rare, predation on eggs and
> chicks is excessive. Suffice it to say that the majority of an organisms
> life is spent in adulthood. This then is the period where defense against
> predators should be strongest. Speed for ostriches, a mean kick for zebras,
> communal defense for water buffalo (e.g., Battle at Serengeti), stealth for
> squirrels, whatever it is, no doubt sauropods were likely able to defend
> themselves (with exceptions of course).