This is a story about 10-million-year-old bones. But it starts in the 1930s.

That's when the federal government launched the Works Progress Administration, or WPA. The Depression-era program paid unemployed people to do things like build roads and paint murals.

In Texas, it also paid people to dig up bones.

The idea was that these bones would be brought back to the University of Texas for study, but it didn’t work out that way.

“World War II happened and that put an end to the research that was going to happen," says Chris Sagebiel, the collections manager at UT’s Texas Vertebrate Paleontology Collection, where the bones now reside.

KUT's Mose Buchele reports

The UT building is a World War II era warehouse that used to be part of a magnesium mine. Inside sit row after row of shelves and cabinets – all full of bones.

“These are pieces of a mammoth,” says Sagebiel, stopping at a shelf stacked with enormous jawbones. “Looking at that number, I know that’s one of our WPA specimens that was collected, probably [around] 1939.”

Many of these bones are still in the burlap and plaster packaging, or “jackets,” they were wrapped in by those WPA workers. But more are now being opened, and they are telling a story of geologic upheaval, climate change and mass extinctions.

“It’s incredibly exciting,” says UT researcher Steven May, who recently published a paper on the WPA bones. “You’re opening one of these jackets that was collected 80 years ago … and you’re pulling off pieces of newspaper from 1939 that they used to cover the fossil with.”

May says he may have already found two new species of ancient animals in the collection: one is a kind of gomphothere, an ancient elephant-like creature with a massive drooping lower jaw; the other is a dog-like creature May says could be an early ancestor to modern canines.

But beyond new species, he says, what’s interesting about the WPA fossils is their sheer diversity. The collection paints a detailed picture of what lived in South Texas about 10 million years ago – long after the dinosaurs, but long before the arrival of humans.

“We have elephant-like creatures; a camel with a very long neck, so it’s sort of giraffe-like; horses,” May says. “We have this rhino, which had a hippopotamus-like lifestyle; they were semiaquatic, we think.”

The fossil record shows such diversity, May calls the environment at this time “the Texas Serengeti.”

“You start thinking about that composition of fauna ... and it sounds very much like some of the modern African-type faunas today,” he says.

But that leads to a simple question: What happened to the animals?

Experts say a bunch of things probably wiped out most of these animals; theories range from asteroids to over-hunting when humans arrived.

But, Sagebiel says, climate change is his "preferred" answer to the question.

“There were large changes in the climate at the same time," he says. "All the large mammals in North America went extinct."

By the time the bones were pulled from the ground in the 1930s, the earth was experiencing a new change in climate – this one caused by humans. The effects of that global warming are now accelerating, which is why Sagebiel thinks this research could be more important today than it was even back then.

By looking at the fossils, he says, “we can see what we might expect in the future, how quickly those effects can trickle down to the animals. This is the laboratory where we study those things.”

There's plenty more to study. Dozens of fossil packages at the collection haven’t even been opened. They could hold anything from a previously unknown animal – to a new clue in a great extinction.

Got a tip? Email Mose at mbuchele@kut.org. Follow him on Twitter @MoseBuchele