The Proboscis Hypothesis

By Lee Anna Sherman

Was the mighty dinosaur done in by a midge?

Very likely, argues OSU zoologist George Poinar in his new book, What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous. Midges, together with millions of other Cretaceous insect species, may well have landed the “final knockout blow” to the giant reptiles by infecting them with deadly parasites and pathogens, Poinar and coauthor Roberta Poinar explain in their richly descriptive narrative.

This “gradualist” theory on the dinosaurs’ mysterious demise contrasts with the “catastrophist” theories most in vogue. But the theories can be reconciled, according to Poinar. In the wake of an ancient global cataclysm — an asteroid strike, a volcanic eruption, a climate swing — even mega-lizards like the 12,000-pound T. rex would be weakened and stressed, he explains. Debilitated, the dinosaurs were vulnerable to bug-borne diseases such as malaria and leishmania.

The 100 million-year-old fossils Poinar studies are not mineralized bones unearthed in archaeological digs. Rather, they are specimens of ancient insects entombed for eons in chunks of golden resin, amber collected from Burma, Lebanon and Canada. Preserved perfectly in Poinar’s laboratory are the beetles, aphids, flies, gnats, termites, leafhoppers, grasshoppers, scorpions, ticks and midges that shared the Cretaceous landscape with stegosaurs, velociraptors and triceratops.

“The minute but mighty insects have exerted a tremendous impact on the entire ecology of the earth, certainly shaping the evolution and causing the extinction of terrestrial organisms,” Poinar writes. “The largest of the land animals, the dinosaurs, would have been locked in a life-or-death struggle with them for survival.”

The dinosaurs lost that struggle. But the mighty arthropod lives on.