CIMARRON — Deep in the tropical jungle of Northern New Mexico, hiding under the 100-foot canopy of trees, the ancient giant predator left an unmistakable mark — when it got its foot stuck in the mud.

Tyrannosaurus rex, one of our state's most famous celebrities, roamed this part of the world around 66 million years ago, back when the now dry, sunny Land of Enchantment was a coastal jungle crossed with swampy, muddy rivers.

But while its toothy grin, massive legs and oddly tiny arms have made the animal an international superstar today, when it comes to digging up dirt on T. rex's mysterious past, the prehistoric paparazzi seem to have been sadly asleep at the switch.

Everything scientists know about the well-known predator stems from about 10 semi-complete skeletons, scattered handfuls of teeth and bone, and a confirmed footprint found at the Philmont Scout Ranch near Cimarron.

"This is the king of the tyrant lizards, the most famous dinosaur ever," said Spencer Lucas, paleontology curator at the New Mexico Museum of Natural History and Science. "And yet we know so little about him. We know he was here in New Mexico, but the sum of what we've found in the state is a jaw from Elephant Butte, some possible teeth and toe bones from near Farmington, and this footprint."

The print was discovered in 1983 by Charles Pillmore, a surveyor from the U.S. Geological Survey. While he suspected it might be from a T. rex, Pillmore didn't have the background to be sure.

So in 1993, Pillmore, who died in 2003, showed his discovery to Martin Lockley, a professor at the University of Colorado in Denver.

Lockley and Adrian Hunt, then a paleontologist at the New Mexico Museum of Natural History and Science, were able to verify the find and wrote a paper about it in 1994. To this date, the imprint remains the only confirmed T. rex track in the world.

"I was very excited when Pillmore showed it to me because I knew that a T. rex track had never been found," Lockley said. "T. rex is such an iconic animal. It was exhilarating to look at it."

What differentiates the Scout Ranch track from those of other animals that lived at the same time is that the imprint preserved an impression of three toes and what's called a dew claw — a small digit that was once a toe that, through evolution, had moved up T. rex's ankle.

The claw is a distinct feature of T. rex, and its impression was preserved when the animal's foot sunk deep in the mud of a river bed as it strolled around prehistoric New Mexico.

"All the other suspected tracks that have been found are a little ambiguous," Lockley said. "They're hard to tell from hadrosaur (duck-billed dinosaur) tracks. Large hadrosaurs and T. rex had similar sized feet. And they were padded, so any footprints, if they're slightly distorted, there's a lot of room for interpretation."

Duck-billed dinosaurs, though, don't have a dew claw. They only have three toes on their feet. So the discovery of the dew claw on the Scout Ranch track was a giveaway, Lockley said.

"It's the right size and in the right place to match a T. rex," Lockley said.

A scientific journey

Until this June, Lucas, who has spent nearly two decades hunting all sorts of prehistoric fossils across the state, had never seen the intriguing track. He made the six-hour trip from Albuquerque on June 29 with Jon Young, a retired National Forest Service archaeologist, to get the site's GPS location for the museum's database.

In the process, he was able to confirm a second T. rex track, which had previously been categorized as that of a duck-billed dinosaur, located about 12 feet from the original track. And he found the bumpy remains of what could be a third track, at the right spot in between the other two tracks, indicating the creature's massive 6-foot-long stride.

"These are cool," Lucas said, walking off the distance between the tracks. "I'm impressed. I'm really impressed. This is one of the most important sites ever found in New Mexico."

Bones can tell us a lot about the size and shape of a creature, but tracks provide a wealth of other information that bones can't, Lucas said.

"It shows you the foot structure of T. rex — the fleshy pad of the feet," Lucas said.

Footprints can also teach scientists about how an animal moved, how it stood upright and how big its gait was, Lucas said.

"One of the things that's debated still is, were these things hunters or were they scavengers?" Lucas said. "Most paleontologists think they were trackers and ambush predators, hunting sort of the same way big cats do today."

Ideas that T. rex was a scavenger come from looking at its small forelimbs. Scientists who support that notion think the animal grew large so it could scare other animals away from kills, and its size was enough so it didn't need slashing forelimbs to attack other animals.

Lucas doesn't agree with that notion, though.

"The argument I would use against that is why does it have these other structures — immense legs, a huge head, ripping teeth the size of bananas — if it was a scavenger," Lucas said. "It was a very fast, very powerful animal. It was a killing machine."

Another indication that T. rex fought for its food is the number of scars and healed fractures in the bones of skeletons found so far. Scavengers wouldn't have fought that much, Lucas said.

"It probably killed with a head blow," Lucas said. "It would have hit one of these 20-foot-long duck-billed dinosaurs with that huge head, maybe slashed at it with its teeth. It's a pretty horrific vision."

The purpose of the almost comically short forelimbs on such a massively powerful animal will likely always remain a mystery, Lucas said.

It's something that's been the subject of a lot of speculation. Some have suggested the limbs were used in mating, others suggested the animal used them as some kind of meat hooks to hold on to flesh after a kill, and a few have even suggested the animal used them for balance when it leaned over, Lucas said.

"Probably they're a vestigial structure, like the human appendix," Lucas said. "It didn't really need them."

Casting a net

The museum hasn't yet tried to collect the tracks because the rock slabs they're on weigh several tons, Lucas said.

To remove them would require some heavy equipment, but getting that equipment up the bumpy dirt road and across a stream to the site would be close to impossible, he said.

"That's not to say we'll never collect it," Lucas said. "But it doesn't seem necessary right now."

The site is fairly remote, and only the Boy Scouts who come to the Philmont Scout Ranch have limited access to the area, which is cordoned off with locked gates and fences.

At some point, between Lockley's last visit several years ago and Lucas' visit last month, the Scouts put a covered barrier over the tracks to protect them from both weather and unwanted visitors.

"God, I'm so proud of this stuff," Young said of the tracks. "And I'm so proud of the Scouts for protecting it like this."

As a retired Forest Service archaeologist, and a dabbler in paleontology, Young said he thinks the site is in good hands.

Both Young and Lucas are former Boy Scouts themselves.

And although the public doesn't have access to the site, the museum has a full cast of the track on display next to the T. rex skeleton replica of Stan, the name given to one of the two most complete specimens ever found. The other well-known T. rex skeleton is named Sue.

The museum bought the cast of Stan in 2008, and it is on permanent display in the atrium.

Looking at the track, Lucas said it appears the animal that made it was about the same size as Stan, so museum visitors can get a good idea of how T. rex looked 66 million years ago when it was roaming our state.

"Stan's foot seems to be a pretty good fit for the track," Lucas said, adding that Stan is about 42 feet long from head to tail.

3-D preservation

The track itself looks different from many other preserved tracks around New Mexico.

At other sites, prehistoric animal tracks often appear as indentations in rocks, but the one from T. rex was formed in a different manner, making the imprint look three-dimensional.

What happened after the massive predator stepped in the sticky mud of a river, is that the footprint remained under the water, and over time the imprint gathered rocky sediment that currents had moved downstream.

The sediment filled in the imprint and solidified, leaving a structure made of a different material than the surrounding rock. Then, millions of years later, the rock around it broke away, leaving the track exposed.

Pillmore wouldn't have discovered it, either, if the rock the track was on hadn't fallen off of a nearby cliff and flipped over, making the track visible, Lucas said.

Another interesting thing about the track's location is how close in the rock record it is to the layer that represents the extinction of the dinosaurs. That layer is about 65 million years old, and the track was found only a few feet below it, Lucas said.

The generally accepted theory is that a giant meteor impact killed off the dinosaurs, either instantly through the blast or by removing food supplies so that they all eventually starved.

Scientists have found debris that likely came from a meteorite in that clay layer, Lucas said.

Finding the track so close to that means T. rex probably saw exactly what happened in that event, he added.

"Tyrannosaurus rex is one of the last dinosaurs that lived," Lucas said. "It may have witnessed the end."

Contact Sue Vorenberg at svorenberg@sfnewmexican.com.

T. REX NUMBERS

A full-sized cast of Stan, one of two nearly complete T. rex skeletons, is displayed in the New Mexico Museum of Natural History and Science atrium, next to a cast of a confirmed T. rex footprint found in Northern New Mexico.

Here are some of Stan's vital stats:

Height: 12 feet at the hips

Length: 42 feet

Stride: 6 feet between steps

Arm length: About 3 feet, similar size to its entire foot

Lived: During the Cretaceous Period, 85 million to 65 million years ago

Environment: Coastal swamplands, tropical forests and jungles

Weight when alive: About 6 tons

Tooth size: Each about the size of a banana

Number of teeth: 50-60

Diet: Other large dinosaurs, including 20-foot-long duck-billed dinosaurs

Stan's skeleton: 70 percent complete

Videos: What we can learn from a track
T. rex stride