[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Seasonal "Day Care" Hypothesis for Maiasaura (Speculation about speculation)

If anyone wants to comment or criticize it, feel free, as it is my first feeble attempt to dabble in dinosaur behavior.<
Ah, behavior. Something that I am really quite interested in, since these were, after all, living breathing animals, and had to have behaved in some way! But, much of behavior of extinct animals must be speculation. That being said, here's my take on the idea:
I personally don't see this as being too likely. This obviously does not mean it didn't happen, I just view it as unlikely. Here's my reasoning, which, no doubt, has some flaws.
I know of know modern animal that has this tactic for reproduction/infant survival. However, I don't think this itself is a strong argument. Most egg-laying animals don't migrate, and this itself mitigates the value of this observation. But I think it's an important one to make.
Secondly, from a "survival of the fittest" perspective, this would not make too much sense. If, for example, you are leaving mostly the elderly/sick animals behind, this would make the nest more vulnerable to raiding. Larger predators (Albertasaurus) in the area would presumably favor elderly/sick individuals in a normally diverse herd. Leaving these animals behind to guard the nests makes them more susceptible to attack from large carnivores. So if the guarding animals are decreased in number, this makes it easier for egg-raiding animals (like Troodon, presumably) to get into the nests. Of course, this argument assumes that the large predators wouldn't follow the herd in the first place. The day care scenario also makes assumtions about gestation periods for the eggs. The animals migrating would have to be on a fairly precise schedule (not too impossible to do, though), to return to the breeding site in time for the eggs to hatch. Otherwise, the day care parents would be forced to try to protect a lot of moving hatchlings, as opposed to large, unmoving nests.
Also, there is no direct proof (as far as I know) that Maiasaura migrated. I agree that it probably did, and the evidence from fossil trackways seems to show that groups of animals moved in herds, but until we find Maiasaura on the north slope of Alaska (there are some hadrosaurs from there, right?), we can't say for certain. I must say, the evidence for Maiasaura migrating is probably pretty good (Two Medicine Bone Bed), however, you must consider that the bone bed is in the same geographic area as the nests, so there's no direct proof that this group actually went anywhere.
Finally, there is the fossil evidence. The Maiasaura nests are not directly associated with many (any?) Maiasaura remains. The bone beds and the nests are in different (overlying) parts of the Two Medicine Formation.
Just some of my thoughts and my own speculation on what I find to be some of the most fascinating aspects of paleontology (behavior).

Student of Geology
Northern Arizona University
P.O. Box 20840
Flagstaff, Az. 86011
AIM: TarryAGoat
"A _Coelophysis_ with feathers?"

Get your FREE download of MSN Explorer at http://explorer.msn.com