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. :-)
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).