Parasites wormed way into dino’s gut

Inside the blackened guts of a 77-million-year-old dinosaur, scientists have spotted a surprise: the once slimy traces of parasitic worms.

Needlelike burrows snaking through the stomach of a duck-billed dino offer the first hard evidence that gut parasites infected dinosaurs, paleontologist Justin Tweet and colleagues report online June 16 in the Journal of Paleontology.

“Maybe they’re right, maybe they’re not,” says paleontologist Anthony Fiorillo of the Perot Museum of Nature and Science in Dallas. “But they’re seeing something no one else has seen before, and that’s pretty awesome.”

Scientists had suspected that, like animals living today, dinosaurs probably hosted parasites and other microscopic organisms. “But that doesn’t mean that anybody ever expected to see them,” says Tweet, a former researcher at the University of Colorado Boulder who now consults for the National Park Service.

Eight years ago, Tweet and colleagues reported the probable stomach contents of a hadrosaur (Brachylophosaurus canadensis) nicknamed Leonardo. Leo’s guts held dark, fingernail-sized flakes that may have once been chewed leaves.

Now, Tweet and colleagues have examined squiggly white tracks amongst the flakes — 280 tracks in 19 samples of gut material. Closer inspection revealed that the tracks look like tunnels, some marked with thin lines, as if little hairs had once brushed by.

The team also found chemical clues that mucus lined the tunnels, leaving behind a fossilized trail of slime. Tweet thinks tiny, mucus-secreting worms with fine bristles might have once burrowed in Leonardo’s belly.

“Dinosaurs didn’t walk the planet alone,” Fiorillo says. “They were part of an engaged and complicated ecosystem.”

Reexamining old fossils could reveal if other dinosaurs had worms, too, he says. Tweet’s paper “illustrates the beauty of the fossil record and how much more we still have to learn from it — if we just keep our eyes open.”