One hundred million years ago, a female sand fly settled on a sauropod for what turned out to be her final blood meal.

Something startled the dinosaur, causing the insect to flee, only to become trapped in the sticky resinous sap of an araucarian tree, where she became a meal for another creature. The resin preserved her remains for future scientists.

		"WHAT BUGGED THE DINOSAURS? INSECTS, DISEASE AND DEATH IN THE CRETACEOUS" By George and Roberta Poinar Princeton University Press ($29.95)

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This is one of the most significant dramas of Cretaceous life that Oregon State University zoology professor George Poinar and retired research scientist Roberta Poinar vividly recount in their new book.

When the Poinars studied that remarkably well-preserved ancient event in their laboratory, they discovered that the dinosaur blood was infected with a pathogenic microorganism.

Had the fly survived to bite another beast, it might well have passed the disease along. As it turned out, bugs had their beneficial traits as well. They were the "Sanitary Engineers of the Cretaceous," playing a major role in recycling the nutrients in dung and the vital chemicals in the bodies of dead animals and plants.

It is impossible to describe life in the Cretaceous Period without paying particular attention to insects, the Poinars say. Their book deftly guides readers through the science essential to that understanding.

When it comes time to analyze delicate evidence in the Poinars' lab, magnificent color images place the readers beside the researchers, lab coats and all. Finally comes time for interpreting findings and drawing conclusions.

While acknowledging that an asteroid impact brought a catastrophic end to the Cretaceous and the dinosaurs (at least the non-avian ones), the Poinars question whether the great reptiles may have already been in serious decline.

Had disease, parasitic infestation, and competition with insects already set them on a path toward extinction?

That is not a new question, but it remains an important one in paleontology. It is the kind of question that continues to inspire scientists and readers alike.

And just as scientists are thrilled by unexpected discoveries like the unfortunate insect in the Poinars' amber sample, readers who love paleontology will savor the discovery of this remarkable book and its fascinating trove of quests and knowledge.