No offense to anybody, but as far as the paleontological community is concerned, this is a dead horse argument. Even Jack Horner, the paleontologist who publicized the hypothesis that
T. rex might have been an obligate scavenger, doesn't believe it anymore (if he ever did so in the first place). It was never a valid scientific theory; Horner never actually did the research on
T. rex remains to back up his hypothesis. More than likely, he popularized the idea just to get people to think outside the box about
T. rex's life habits, or even for the publicity (He has been quoted as stating that he sometimes broached the subject just to be contrary and to get his colleagues arguing). And for the record, another paleontologist eventually did do an evaluation of
T. rex's anatomy, and found that none of Horner's claims about
Tyrannosaurus being physically ill-suited for predation stacked up. In short, everyone agrees that our favorite sharptooth would have scavenged whenever palatable carrion was available, and hunted when it wasn't, just like any other terrestrial carnivore.
Again, forgive me if I sound annoyed, aggressive, or like I'm trying to censor the discussion (I promise I'm not). All I can say is, to anyone who's still wondering about this subject, read
this article. If it's anything to go by, paleontologists are tired of hearing the "
T. rex: hunter or scavenger" question, and very keen on spreading the word that it's not something people have to debate anymore.
Well, maybe the tall grass was taller back then! Maybe it would have worked if they hid!
There was no grass in the dinosaur age, though trees like redwoods dominated the planet, perhaps they could conceal a 20 foot tall, 40 feet long Tyrannosaur.
Actually, in 2005, paleontologists discovered phytolithsófragments of silica uniquely found in grassópreserved inside titanosaur dung from the late Cretaceous of India. So evidently grass of some form did exist at least at the end of the Mesozoic, though I don't know if there's any evidence that there were grassy fields like we have today, or if they were more like bamboo thickets (bamboo itself being a giant, woody grass). In any case, there surely must have been
some kind of plant that filled the role of grass back in the Mesozoic, so you're certainly right that there would have been
something for ambush predators to hide in.
Source:
http://www.newscientist.com/article/dn8336...ml#.UfeIqBZhung