This is a question I get asked a lot. The public seems enamored with this notion that T. rex didn't actually hunt. It's bizarre. They're all so very disappointed by the idea, and yet obsessed with it, almost as if they're actively looking for a reason to pout about scientists making T. rex ultra lame. "Gee, way to go and let us down again, science. Party poopers. Pluto killers."
Allow me to clear some things up. The hunter/scavenger debate is not a major point of controversy in paleontology. Not by a long shot. It was just a suggestion brought up by Jack Horner back in the early 90s, and no one in the paleontological community has flipped out over it (and if no one's flipped out over it, then it's not a big deal, because paleontologists enjoy flipping out over things).
"Okay, okay. So which is it already?!"
The answer to the question of if T. rex hunted or scavenged is basically...they did both. Just like any modern carnivore.
There's been some hubbub recently about a cool fossil find where a hadrosaur vertebrae has a T. rex tooth embedded and healed over, which implies the T. rex bit this dinosaur when it was still alive and had time to heal. Therefore, likely evidence of predatory behavior on the part of the T. rex. It's being touted as the "nail in the coffin" on the scavenging theory, which just kind of makes me roll my eyes. This is a neat find, to be sure, but doesn't do much other than to affirm what other evidence has already implied: T. rex could both hunt and scavenge.
Many modern carnivores hunt while also supplementing their diet to varying degrees with scavenged meat. That's really how most predators go about their lives. Does it make them less fearsome? Not really. They can still kill things.
So as far as my reaction to this particular piece of pop culture dinosaur news, I'm nodding along with basic interest, but not flabbergasted (as many people have expected me to be). Sorry if I've burst anyone's bubble. I wasn't even going to cover this story on my blog, but I've had enough people ask me about it that I felt like I probably should address the issue, and address why I wasn't more super-psyched about it.
Remember, just because a predator is eating something already dead doesn't mean it couldn't kill you.