Scientists Put Alligators on a Treadmill

When humans and mammals breathe, the ribs lift upward and outward, expanding the chest volume. Simultaneously, the diaphragm contracts and moves down, further increasing the volume.

Carrier and Farmer found that when alligators inhale, certain muscles pull the pubic bone downward to expand the abdominal cavity.

"We stumbled into a mechanism that was actually quite surprising," Carrier says. "The pelvic girdle was playing a role in lung ventilation."

So what does that have to do with dinosaurs?

"Dinosaurs have an extra set of ribs that run along the belly, and the function of those ribs has remained an enigma," Farmer says. "Some people think they were to protect the belly and other people have speculated that maybe they played some role in breathing. Our work shed some light on that. They probably were actively employed in breathing."

The belly ribs were long and thin, and thus unlikely to have been part of the animal's protective armament, she adds. The ribs probably were attached to a rocking pelvic bone that moved, thus expanding the breathing cavity and allowing the animals to run and breathe at the same time.

Of course, a lot has changed since dinosaurs took their last breaths.

Alligators have opted for the simple life, preferring to lie in mucky water and wait for prey to come by instead of chasing it down. As "sit and wait predators," they don't really need that rocking pubic bone any more, but they still have it.

As for those five gators in Utah, they have to earn their daily ration of mice, goldfish and eggs by running on a treadmill for awhile longer. After the research project is over, they will be returned to the refuge in Florida to retire and bask in the sun.

Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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