Dinosaurs may ultimately have been killed off not by a huge asteroid but by tiny germs.
Evidence for this, says George Poinar of Oregon State University, can be found in amber mined from deposits in Lebanon, Canada, and Myanmar (Burma).
Amber is a semiprecious gemstone formed from fossilized tree sap. Sometimes the sap entombs ancient insects, preserving them in exquisite detail.
By examining such creatures—including mosquitoes, ticks, and other bloodsuckers—Poinar has found evidence that they carried the same deadly diseases that affect animals today.
(Related news: "Mastodons Driven to Extinction by Tuberculosis, Fossils Suggest" [October 3, 2006].)
For example, "some of them carry malaria," he said. "We also got parasitic protozoa and worms from dinosaur dung."
The rise of disease-carrying insects coupled with dramatic disasters such as asteroids or volcanoes would help explain why the dinosaurs died out relatively slow, possibly over the course of several million years.
"It was not just one disease but a number of diseases together which would have debilitated dinosaur populations," Poinar said.
He and his wife Roberta lay out their theory in a new book called What Bugged the Dinosaurs: Insects, Disease, and Death in the Cretaceous.
Microscopic Examination
Poinar believes that previous researchers overlooked bugs as a key culprit because they didn't have training in his original specialty: insect-borne diseases.
"It's very unusual for a parasitologist to become a paleontologist later in life," he said. "I knew what these disease pathogens looked like in insects."
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