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Las Cruces Sun-News, Norm Dettlaff, Associated Press
In this photo taken March 1, 2011, Jerry MacDonald touches one of the fossilized trees he discovered in the Robledo Mountains near Las Cruces, N.M. Smithsonian scientists were at the Prehistoric Trackways National Monument along with MacDonald, who discovered the trackways of prehistoric animals, to learn more and study the geological formations that give hints about what the area was like toward the end of what’s known as the Permian Period.

LAS CRUCES, N.M. — Rock picks clinked musically against solid, gray stone, as two researchers from the Smithsonian's natural history museum in Washington, D.C., chipped away at a hillside, looking for signs of the ancient past.

And voila — pay dirt! Or pay rock, rather.

Dan Chaney, a Smithsonian research assistant and one of the pick-wielders, showed off his find: a hefty rectangular chunk of rock, marked by dark lines running the length.

"This is the piece of a trunk of a tree," he said. "This one was smashed flat. We're interested in these fossils because they help us answer the questions we're interested in."

That tree remnant, found in the Prehistoric Trackways National Monument northwest of Las Cruces, was alive some 290 million years ago.

A handful of fossil and geology experts visited Las Cruces this month to tour the monument in the Robledo Mountains, looking for fossilized plants and studying the geological formations that give hints about what the area was like toward the end of what's known as the Permian period.

At that time, a massive, single continent, Pangaea, existed on Earth, and the world's climate was shifting out of an ice age, said Bill DiMichele, paleobotanist with the Smithsonian's National Museum of Natural History.

The Robledo site sits at what was once the farthest western edge of the continent and is different from fossils of the same age that are found in other parts of the world, he said.

DiMichele, who visited the Robledos once before, said the site gives new insight.

"This is intrinsically very interesting by itself, and it's interesting in the large picture, as well," he said.

For instance, DiMichele said, a conifer specimen found in the monument has been shipped to a colleague in California, who indicated it was previously unknown.

Piecing together what the environment was like millions of years ago and how the fossils were formed is akin to looking at the broken bits of a vehicle collision and trying to figure out how it happened, said Scott Elrick, a geologist with the University of Illinois, who also was visiting.

"We're reconstructing the accident," he said.

On one day, the scientists, along with 13 Onate High School students and a teacher, explored a fossil bed running the length of an arroyo beneath a rock ledge. The researchers theorize it formed after a mudslide sent plant material and charcoal into a broad channel. It was mixed with saltwater.

The students, members of an Advanced Placement biology class, asked questions and checked out petrified logs that protrude from the arroyo. Alan Hernandez, 19, a senior student, found a fossil himself.

Hernandez said he's often wondered about geology during outdoor excursions with family.

"Now when I go on hikes, I'll look at things a little more intellectually," he said. "It's something really neat; I'll definitely look into it in college."

The students were there on a field trip and also part of a grant project awarded to DiMichele from the U.S. Bureau of Land Management, which oversees the monument.

The project entails not only researching fossils in the park, but also creating scientific illustrations about what the area might have looked like in the past as well as video podcasts that will be posted online, said Lori Allen, BLM planner for the monument. The grant totaled about $23,000, she said.

"Obviously, (the researchers) are getting their own information," she said. "Then, we'll take that information and get it out to the public."

Filming footage for the podcasts was a crew of students from New Mexico State University's Creative Media Institute.

"We love the project," said Philip Lewis, director of the institute. "Literally generations will be able to view these podcasts, which feature what are the top experts in their fields."

Acting as a tour guide of sorts for the visiting scientists is Jerry MacDonald of Las Cruces, an amateur paleontologist who's credited with uncovering many of the fossilized animal footprints that give the monument its name. MacDonald said other researchers who specialize in vertebrate animals and insects have visited the park. He said about 125 significant fossil beds have been identified so far within the monument's 12-square-mile area.

MacDonald said he's been exploring the mountains for 27 years, cataloging fossil sites. Witnessing other researchers tour the discoveries is rewarding, he said.

"Just as gratifying, if not more gratifying, than finding the things is to see these guys explain what in the world was going on at that time," he said. "What we're finding here is just phenomenal on a number of different avenues."