Sauropods like Brachiosaurus and Diplodocus were the biggest beasts to ever roam the Earth. And these dinosaurs had enormously long necks. Which poses an anatomical problem: they needed to move their necks side to side and up and down to graze, but that requires lots of muscles. And muscles are heavy. So how did they keep their heads from dragging on the ground?

It looked like their secret was thin riblike bones—some up to 10 feet long—that ran the length of the sauropods' necks. Because when researchers examined slices of those bones under the microscope, they found that they aren't normal bone at all—they're ossified tendons. That’s according to a study in the journal Biology Letters. [Nicole Klein, Andreas Christian and P. Martin Sander, Histology shows that elongated neck ribs in sauropod dinosaurs are ossified tendons]

The researchers think those long tendons may have allowed the dinos to shift muscle mass from their necks onto their bodies—giving them a sort of "remote control" over their necks, while making the neck lighter and more flexible. Not too different, in fact, from how herons do it today.

And that, the authors say, may have been the sauropods' key innovation. Helping them to graze more efficiently, and stay neck and neck with other dinos.

—Christopher Intagliata

[The above text is a transcript of this podcast.]