An undated photo at Grand Canyon National Park shows the fossilized tracks of an unidentified creature that researchers believe lived about 315 million years ago.

Grand Canyon has been a national park for a century—but we’re still learning its many secrets. Recently, a rock fall revealed the oldest fossilized tracks ever recorded in the Canyon. They’re the footprints of a reptilian creature that walked through wet sand 310 million years ago.

Quicksand may not be as common as adventure movies might lead one to believe, but that doesn't mean that getting stuck in the stuff is entirely inconceivable.

When you’re out hiking in the Grand Canyon, you never know what you might see. You could cross paths with lizards, tarantulas or maybe even something bigger like a javelina. More likely, you’ll also come across the tracks of these critters.

Fossilized reptile prints older than any dinosaur were recently discovered in the Grand Canyon.

When you’re out hiking, you never know what you might see. You could cross paths with lizards, tarantulas or maybe even something bigger like a javelina. More likely, you’ll also come across the tracks of these critters.

When you’re out hiking, you never know what you might see. You could cross paths with lizards, tarantulas or maybe even something bigger like a javelina. More likely, you’ll also come across the tracks of these critters.

Long before the Grand Canyon formed, a primitive reptile the size of a baby alligator skittered sideways across the wet sand of an impossibly ancient coastal plain.