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So you can order your own fries instead of eating everyone else's.

Trains, now on Uber. T's and C's apply. Check the Uber app. This is a scientific American 62nd science. I'm a lien organ bran.

Fossil footprints help tell us how ancient people lived, but such physical impressions are hard to find.

You get all of these footprints from different species in the same time period interacting,

and you can't see them all the time and some of them you can

never see with the eye that is but we can still detect them with geophysical

sensors. Cornell University archaeologist Thomas Urban, he and colleagues used ground penetrating radar,

GPR, to detect invisible traces of footsteps in White Sands National Monument in New Mexico.

Their GPR device goes back and forth over an area in a grid pattern, which ultimately creates

a 2D radar gram.

The technique detects subtle differences in ground density.

Speaking about one set of otherwise imperceptible animals footprints, he says.

These were caused by compression of sediment beneath the animal's track and they relate to the weight and

momentum of the animal.

Twelve thousand years ago, the White Sands area was a large muddy flat, which was covered

with footprints from various species.

Urban is excited about the story so many footsteps suggest.

For example, the researchers found no evidence of shoes or sandals. They did find human and animal tracks crossing each other,

which suggests the prints were left during a hunt. The findings are reported in the journal Scientific Reports.

This sort of unique setting, you know,

has recorded all of the daily movements of people

...