regarding the discussion on pack hunting strategies in extant animals, i think an extreme (at least on land) is the case reported in the november issue of National Geographic , about the unusual (dangerously unusual i'd say) hunting behavior reported for the lions of the Chobe National Park(Botswana): they hunt elephants.
I've seen it before , but those were isolated episodes and usually occured when some lions were "lucky" enough to find weak individuals , old ones or really young ones and were able to isolate them; in this case, however, it seems like they have begun assaulting not only those kinds of elephatnts but also young adults (perhaps sometimes unsuccesfully, but it isn't so important).
This unusual choice of the targets, is said(in the article) to have been taken place because of the extreme conditions in that area, where big groups of pachiderms are packed together with lions and other animals near to the rare water pools present .
The result is that ,put in the need of drinking, lions can't escape every time elephants get close;
from this condition to the opposite one, the step should not be too big......
I think this could also be a possible explanation of the causes that could have led to that mono-specific(is it correct?) association; some theropods (perhaps members of the same group) could have had some problem of comprehension with some big animals near a water pool, much deeper than wide on its surface.
Given the possibility of a similar enviroment , where and when those theropods died, and a modality of deposition that could be interpreted as the result of this fact( theropods fallen in a deep and somewhat muddy water pool), would it be so unlikely to have happened in reality?...i really don't know and surely there are out there many people knowing this kind of thing much better than me, so i hope someone will have something to say.