Back in the days of Tyrannosaurus Rex, bugs didn't pick on critters their own size.
Dinosaurs would do just as well, and an upcoming book by two Corvallis scientists say bugs with diseases and parasites may have led to the undoing of Rex and his reptilian pals.
The book by George Poinar Jr. and Roberta Poinar, whose research served as the inspiration for "Jurassic Park," says insects may have diminished plant food sources as well.
"What Bugged the Dinosaurs," published by Princeton University Press, comes out in January.
"We think insects played an important role in determining the fate of the dinosaurs, and a lot of people haven't considered that yet," said George Poinar, a zoology researcher at Oregon State University, and a leading expert on insects trapped in amber.
Poinar, 71, is a courtesy professor at Oregon State University. He isn't paid but he is a member of the zoology department and gets to use OSU facilities for his research. ,
John Ruben, chairman of OSU's zoology department, said he wasn't sure his colleague was on the right track, but didn't discount his suggestion entirely.
"I don't know of any particular evidence that would point to a link," said Ruben who teaches dinosaur biology. "It was probably a lot of things working together to cause their extinction. ... Extinctions are very complicated.
"We don't know why animals that lived at the same time people lived went extinct. Dinosaur extinction, we're talking about 65 million years ago."
George Poinar said bugs likely were just one factor.
Climate change, ocean regressions and volcanic activity may have contributed, he said.
Even 100 million years ago, bugs were pests. Poinar studied bugs trapped in amber that bore diseases and even pathogens from cold-blooded vertebrates, some of them probably dinosaurs, he said.
He said insects also would have competed for the same plant food and led to the rise of flowering plants, which pushed aside species such as ferns that some dinosaurs relied on.
Ruben said many dinosaurs flourished after the rise of flowering plants, however.
"There's no evidence that dinosaurs were dying from disease based on the bones," he said.
Poinar has been studying amber for about 30 years, and he and his wife have worked on two books about it.
In a separate development, Poinar and OSU researchers recently identified a soldier beetle, preserved almost perfectly in amber, that was using chemical repellents to fight off an attacker when an oozing flow of sap engulfed it.
"This was a really interesting find, because it not only doubled the age of this particular group of beetles, but it showed that insects had already developed chemical warfare 100 million years ago," Poinar said.
The findings were just published in the Journal of Chemical Ecology.
"''We're investigating the ancient life, what the ancient ecosystem was like, by looking at various bugs and flowers from various parts of the world," Poinar said.
OSU scientists say bugs could have helped doomed dinosaurs