The Dinosaurs' Nemeses: Giant, Jurassic Fleas

Enlarge this image toggle caption Wang Cheng/Current Biology Wang Cheng/Current Biology

Fossil-hunting scientists are coming to grips with a new discovery that could change forever how we think of dinosaurs. What they've found is that dinosaurs may well have been tortured by large, flealike bloodsucking insects.

Yes, it appears that the greatest predators that ever roamed Earth suffered just as we mammals did — and as we still do. Fleas were thought to have evolved along with mammals — they like our soft skins and a diet of warm blood.

But now scientists in China have discovered Pseudopulex jurassicus and its equally tyrannical cousin, Pseudopulex magnus — magnus as in "great."

Indeed, they were big — several times as big as current fleas — and equipped to feed. "They have this large beak," says zoologist George Poinar Jr. "Oh, it looks horrible. It looks like a syringe when you go to the doctor to get a shot or something."

Poinar, an emeritus professor at Oregon State University, studies life forms preserved for millions of years in amber, or ancient tree sap.

He calls these insects pseudo-fleas. They were found by Chinese scientists, preserved in amber. Besides being bigger than modern fleas, their legs are unusually long. Poinar says the legs don't look like they're built for jumping, as with modern fleas, but perhaps for grabbing onto the bumplike scales on a dinosaur so they could jab that proboscis into the skin between them.

Let's face it: They're the only small creature that would attack a dinosaur. Anything else that was larger would definitely have been eliminated.

"Let's face it," he says, "they're the only small creature that would attack a dinosaur. Anything else that was larger would definitely have been eliminated."

It's been a veritable flea circus lately in the fossil-hunting business. Just last month Chinese scientists announced the discovery of another set of flealike insects preserved in amber. They're much like the new ones Poinar examined, which are described in the journal Current Biology. A team of scientists led by Tai-ping Gao at Capital Normal University in Beijing found them.

Poinar says the world about 150 million years ago apparently was getting increasingly buggy, and those insects were changing the dinosaurs' world. They did that in at least two ways. Because they were pollinators, insects probably encouraged the evolution of flowering plants rather than fernlike plants. Plant-eating dinosaurs that couldn't adapt to a new diet would've been in trouble.

And scientists who study dinosaur feces — yes, they do do that — say dinosaurs had diseases, parasites and worms. Poinar says they probably got some of them from insects like these pseudo-fleas. "To a lot of them, this was something brand new they hadn't been exposed to before," he says, "and it would have decimated the population. And it wasn't just one disease but a combination of diseases."

He says those diseases could have hastened the demise of dinosaurs.