NASA and dinosaurs, together at last.

The space agency, better known for blowing our minds with announcements about black holes or potentially habitable star systems, surprised everyone with big news that hits much closer to home: the discovery of an exceedingly rare sandstone slab of dinosaur and mammal footprints.

Unlike the agency's other discoveries regarding celestial objects millions of miles or even light-years away, this one conveniently happened behind NASA's Goddard Space Flight Center in Greenbelt, Maryland.

It all started with a stroll

Amateur Paleontologist Ray Stanford in 2012, pointing out the exposed edge of a giant sandstone slab of rare mammal and dinosaur footprints. Amateur paleontologist Ray Stanford in 2012, pointing out the exposed edge of a giant sandstone slab of rare mammal and dinosaur footprints. (Photo: Rebecca Roth/NASA/GSFC)

Back in 2012, amateur paleontologist Ray Stanford was dropping his wife Sheila off for work at Goddard when he decided to take a stroll of the grounds behind the building. There, on an exposed hillside, he spied what appeared to be the weathered 12-inch-wide print of a nodosaur, a kind of "four-footed tank." Further examination and subsequent excavation of the site revealed a sandstone slab 8 feet by 3 feet and embedded with nearly 70 footprints from eight species of mammals and dinosaurs.

According to paleontologists, the tracks were likely imprinted in the mud over only a few hours. A flood then swept through the area, preserving the moment until Stanford's chance discovery more than 100 million years later.

'The mother lode of Cretaceous mammal tracks'

Detail of some of the mammal tracks included on the 100-million-year-old sandstone slab. Detail of some of the mammal tracks included on the 100-million-year-old sandstone slab. (Photo: Rebecca Roth/NASA/GSFC)

"The concentration of mammal tracks on this site is orders of magnitude higher than any other site in the world," Martin Lockley, paleontologist with the University of Colorado, Denver and co-author on a new paper on the discovery, told NASA. "I don't think I've ever seen a slab this size, which is a couple of square meters, where you have over 70 footprints of so many different types. This is the mother lode of Cretaceous mammal tracks."

In addition to the nodosaur print (which features a smaller, baby nodosaur print beside it), the slab also includes the dinosaur tracks of long-neck, plant-eating sauropods, carnivorous theropods, and even those of flying pterosaurs. It's the mammals, however, that are most intriguing, with some 26 prints attributed to small species the size of squirrels or prairie dogs.

"This is a big deal," Lockley added to Fox 5 DC. "We have more and better mammal footprints that really have been found anywhere in the world from this time period."

A NASA volunteer works to excavate the slab containing the fossil footprints in January 2013. A NASA volunteer works to excavate the slab containing the fossil footprints in January 2013. (Photo: Rebecca Roth/NASA/GSFC)

Lockley and Stanford believe the density and wide diversity of the tracks suggest that the different species were all actively feeding in the area, even perhaps on each other.

“One could literally make a movie about everything going on in this slab,” Stanford told the Washington Post.

Goddard will now display a fiberglass copy of the slab on a wall in its Earth Science building. The original, for now, will remain in a warehouse in Maryland for further study.

You can see a video of Stanford and Lockley discussing the rare slab in detail in the video below.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Ancient slab of dinosaur tracks discovered behind NASA Space Flight Center
The 100-million-year-old sandstone slab of 70 mammal and dinosaur tracks from the Cretaceous period is one of the rarest ever discovered.