- Associated Press - Tuesday, July 5, 2016

SNYDER, Texas (AP) - Long ago, herds of wild beasts roamed this area. Their bodies rose from the tall grass, lumbering along as they lived out their lives on the plains.

It wasn’t shaggy fur covering these animals, however, but hard shells.

“We have tortoises in North America today, but they’re gopher tortoises in the desert southwest, into Texas and Florida, and they’re about this big,” John Moretti told the Abilene Reporter-News (http://bit.ly/296JPLZ), using his hands to suggest something about the size of a football.

“They’re coldblooded, so if it gets too hot or too cold, they’ll burrow to get out of the extreme weather.”

Moretti is a graduate student with the Museum of Texas Tech University and the supervisor of a paleontological dig just east of town on the Roland Springs Ranch. This marks the 11th year of the excavation of a former streambed on the privately owned property.

The ancient tortoises, known as Hesperotestudo, lived near Snyder more than 2 million years ago, the time period of the excavation, and were quite a bit larger than a football. Like the Galapagos tortoises you might find in a zoo, these were more the size of a coffee table.

“A tortoise this big, they can’t burrow because their legs are pretty much columns, they have to be to hold that shell up,” Moretti said. “So you have to presume from that evidence that there weren’t long-term cold periods. We didn’t have winters with a week of 20-something temperatures like we can have now.”

At about that time, the ice age was just beginning to start. The glaciers eventually would reach as far south as Nebraska. The resulting climate change with that much ice so near to this area made it milder than it is today.

“The summer was probably not getting up to 100 degrees, so that helped the grassland to be a wetter place,” Moretti said. “Maybe there’s not too much more rain, but if we don’t have high rates of evaporation, the effective moisture is greater and it makes a wetter habitat.”

Tortoises aren’t the only animals to be found in the dig, more than 50 different species have been documented.

“Birds, reptiles, amphibians, fishes and mammals of all body sizes,” Moretti said.

Each June, Moretti has led a team of other students and volunteers back to the ranch. When excavation ends for the year, the site is covered with layers of plastic and dirt, so researchers’ first few days always are spent restoring the dig to a workable state.

Once excavation resumes, a grid is outlined across the entire site to allow for documentation of every action.

Workers use small trowels and dustpans to scrape millimeters of dirt away, then bag the specimens for later inspection. Every couple of layers, a new reading is made of that particular spot’s height, which is noted on the bag.

If you think that sounds incredibly tedious, then you haven’t seen what they do with the dirt from the bags. It’s taken to a fine sifting screen, where water is washed over it to separate the tiny bones of ancient rats and mice from the pebbles and other sediment that trapped them.

“Some of the mice we find, their teeth are so small they can actually slip through holes in the screen. They’re really minuscule,” Moretti said.

Why search for mouse teeth?

“Teeth are very durable, they’ll last a lot longer than the jaws themselves,” he said.

It takes a special kind of person to do this sort of work. I’ll tell you right now that I’m not that kind of person.

But this is how the scientific method works. Collecting this data will allow Moretti to build a three-dimensional model of the dig.

“Then we’ll use the spatial information to throw those bone points in on top of that model,” he said. Placing the locations of the excavated bones in the computer model will be an incredibly valuable research tool as the excavation progresses.

This year’s dig is scheduled to wrap in mid-July. Each Saturday the Scurry County Museum has been sponsoring tours to the site.

Children attending the museum’s Dino Camp visited the dig earlier this week.

Dinosaurs died out 63 million years before the animals being found in this dig, so there might have been some disappointment at not seeing a T. rex. But giant tortoises do run a close second, and Moretti was able to convey the idea of how long ago in time this stream existed.

“I was trying to impress on them a few things, that this is paleontology and this was 2 million years old,” he said. “One of the kids raised his hands and asked, ‘So next year, it’s going to be 3 million years?’”

No, Moretti said. Next year, it will be 2 million-and-one years old.

“Wow, that’s a really long time!”

Yep, even for a tortoise. Not so much if you’re sifting mouse teeth, though.

___

Information from: Abilene Reporter-News, http://www.reporternews.com

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