Killing a Legend (cont'd)

The most common professional objection to Horner's scavenger hypothesis is that most predators will scavenge if they stumble across a free meal, and many scavengers will kill prey when the opportunity presents itself. T. rex, this argument goes, was almost certainly an opportunist — both a scavenger and a predator as the situation dictated.

Horner gives no quarter on this issue. "It is," he says, "bad science. What's the evidence for hunting? Just opinion?" Is there any evidence at all that Tyrannosaurus rex ever hunted? "None whatsoever."

As fascinating and controversial as the T. rex hypothesis is, however, the Hell Creek Project is after much bigger scientific game: a comprehensive snapshot of an ecosystem that disappeared 65 million years ago. By the time the five-year project ends in two more years, Horner says, "we should have the data to reconstruct this ecosystem."

No paleontologist has ever attempted such a large system reconstruction. Until fairly recently, Horner says, dinosaur research had a great deal in common with butterfly collecting — basically digging up bones and putting them on display with too little thought given to the context in which the giants lived.

Hell Creek is an ideal place to start. The formation is relatively continuous, clearly bounded and easy to identify. The sediments span about 3 million years, roughly the estimated duration of a species — before it disappears or evolves into a new species. That should permit an evolutionary study of how dinosaur — and perhaps mammal, mollusk and plant — species changed over time and in response to their environment.

And the 3 million years of Hell Creek end at a critical moment — the KT Boundary that marks the extinction of the dinosaurs some 65 million years ago.