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Re: "Tyrannosaurus was not strictly a predator"



 Something jumped out at me that seemed unusual in the latest on the
 Hell Creek fauna, Horner, Goodwin and My[hr]vold (2011):

 "This census suggests that *Tyrannosaurus* was not strictly a
 predator, but instead more of an opportunistic feeder, possibly
 selecting similar food choices under circumstances comparable to that
 of hyenas in extant ecosystems, a trend unrecognized in earlier
 census studies."

Wow. That's nothing short of a strawman that they're burning here.

Really, has anybody ever claimed that *Tyrannosaurus* was a pure predator that shunned free lunches? After all, and this has been repeatedly mentioned in the primary literature, there are no extant big vertebrates that behave this way. Cheetahs come close, but even they have been documented to scavenge in the rare instances that they think nobody will chase them away from the carcass too soon.

In the scientific literature, the debate has never been "pure predator vs. pure scavenger"; it has been "opportunistic predator vs. pure scavenger". To imply otherwise is flat-out dishonest; I cannot see how Horner et al. -- or for that matter the reviewers of their manuscript! -- could possibly plead ignorance on this point.

It's also a bit strange how Horner et al. don't make it explicit that they've changed their point of view: they used to be on the "pure scavenger" side of the debate, now they're on the "opportunistic predator" side... where everyone else is, so the debate is over, even though the quote above explicitly pretends otherwise.

By the way, how much scavenging hyenas do varies geographically. In some places, the scenario we're used to holds: the lions hunt, and the hyenas eat the remains. But there are also places where the hyenas do most of the hunting, and then the lions come, chase the hyenas away from the carcass, and scavenge -- so the hyenas hunt for themselves _and_ for the lions.