1. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
virtual
FIELD TRIP
We’re going on a Friday Field Trip! Pay close attention to the presentation and then we’ll finish up the class with some fun activities.

2. Virtual Field Trip A Day in the Desert Digging Dinosaurs
In June 1997, I was lucky enough to join a research team on one of their dinosaur digs in Big Bend National Park, Texas. The trip was part of a summer class at the University of Texas at Dallas, led by Dr. Homer Montgomery.
This presentation is actually part of the project I turned in for my grade! I thought you might enjoy seeing some of my ‘homework’ and have fun on this one-of-a-kind “Friday Field Trip”.
with Dr. Homer Montgomery, The University of Texas at Dallas

3. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
The “Bend” in the River
Big Bend is just what it sounds like – where the Rio Grande Wild & Scenic River makes a big bend or curve! Big Bend National Park is located in West Texas, approximately 70 miles south of Marathon, Texas. It includes a few small ghost towns, several visitor centers, campsites, and a lodge.

4. Geologic Map Big Bend National Park
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Geologic Map
Big Bend National Park
Big Bend is 97% Chihuahuan Desert, bordered on three sides by mountains that block the rain.
Remember what age the green formations usually indicate? (Cretaceous.) The red spots are later Tertiary volcanics and conglomerates.
The exact location of the dig site is confidential, really. Dinosaur bones are a hot item these days and some people will literally destroy an area looking for sites to steal protected artifacts. The Federal Government has granted Dr. Montgomery complete control of this particular dig site. He decides who goes to it and what is done with it. That in itself is a big responsibility.
After this presentation, I hope you’ll appreciate the hard work of paleontologists and respect the value and importance of such discovery sites and the scientific process.
Geologic map scanned from the Geology of Texas, The Bureau of Economic Geology, The University of Texas at Austin, 1992.

5. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Breaking Camp
Field work starts early… We were up at 5:00am, ate breakfast, and hit the road by 6:30 most mornings.
The weather has a lot to do with how much work you can get done during field research. In the desert you really have to worry about the extreme heat. Temperatures have been recorded up to 180° at mid-day in the summer.
That’s hot – and it feels even hotter when you’re carrying all your gear, water, tools, and eventually, huge dinosaur bones with you!
We took a van most of the way; however, no vehicles are allowed off-road in the National Park, so…

6. Hiking across the Desert
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Hiking across the Desert
You’d better bring a good pair of boots to hike almost 2 miles out to the dig site! It took us about 45 minutes at a good, steady pace.
The scenery was beautiful in its own way. Most people think the desert’s a dead, desolate place, but we saw a lot of life along the way…

7. Lots of Cactus! What animals would you expect to find in the desert?
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Lots of Cactus!
What animals would you expect to find in the desert?
Well, in addition to lots of sunshine and the prickly cactus scattered all over the place, we happened to see:

8. Roadrunner … a quick-moving roadrunner who blazed the trail at first;
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Roadrunner
… a quick-moving roadrunner who blazed the trail at first;

9. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Millipede
… lots of millipedes climbing the bushes in search of their breakfast;

10. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Lizard
… a colorful lizard whose thick skin helps keep him from burning;

11. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Jack Rabbit
… a friendly jack rabbit whose big ears help keep him cool by radiating heat;

12. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
More cactus…
… some more prickly cactus with thick, fleshy stems to hold water;

13. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Snail?
… a bunch of desert snails whose shells were bleached by the sun;

14. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Rattlesnake!
… and even a rattlesnake who gave us fair warning of his whereabouts! We stayed out of his way and just kept hiking toward the dig site…

15. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Narrowing the Field
In this entire expanse, how do paleontologists know where to start digging for dinosaurs? They have to do some detective work.
What age would the rocks need to be to contain dinosaur bones? (Cretaceous-Jurassic.)
What type of rocks would successfully preserve dinosaur bones? (Sedimentary – mudstone, siltstone, sandstone.)
Trained, experienced geologists search certain potential areas that have rocks of the right age in the right setting.

16. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Bone Scatter
The first clue of a possible site is a bunch of bone scatter. These bone fragments were piled on top of a nearby hill. Fossil bone looks quite different from the surrounding rock - if you know what you’re looking for!
What differences might you notice to identify a bone fragment? (Color, texture, symmetry, etc.)
Is this where the bone was originally deposited or has it been moved by animals, water, or other events? Hmmm.

17. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Marking the Site
Once a significant site has been found, it is extremely important to record all the details of the site, especially its location. Pages of notes and measurements will help put all the pieces together back in the lab.

18. Global Positioning System
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Global Positioning System
Mapping is a lot easier to do now with electronic Global Positioning Systems, or GPS. This hand-held device uses 3-10 satellites to determine the position by calculating time differences. It’s accurate to within 10 meters! After waypoints are entered, navigation screens automatically update the distance, speed and bearing between locations. This model is a “Magellan”.
It would be too easy to get lost in this vast, hot desert.

19. GPS - How it works Satellite Vehicle Orbit Diagram Satellite Launch
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
GPS - How it works
Satellite Vehicle
Orbit Diagram
This will help give you an idea of how electronic Global Positioning works.
Satellite Launch
"Global Positioning System” is a network of 24 satellites which orbit the earth, lauched by NASA, and maintained by the U.S. Air Force. Originally designed for military use, the GPS system is now used for civilian navigation through the use of inexpensive, hand-held portable GPS receivers.
Captured from the Telson Communications, Inc. web site (

20. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Exposed Bone
After days of digging out the overlying sediments - called overburden - that have protected the bones all these years, larger, better preserved bones start to be discovered. For example, this rib is shown in place, as it was uncovered.

21. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
The Alamosaurus
After almost 2 years of work at this dig site, scientists believe that these bones belong to the largest dinosaur ever found in Big Bend, the Alamosaurus.
Dana, the geologist who discovered the site, drew this sketch. It shows a cutaway of the first femur, a leg bone, the team discovered.
Adult alamosaurids may measure up to 22 meters long and may have weighed almost 28 tons. These were the plant eaters. They had huge bodies and really long necks. It appears that there are one adult and three juveniles at this site.
What do you think they might have been doing? (Babysitting, triplets, birthday party, group mother, etc.)
Sketch by Dana, captured from the UT- Dallas Dinosaur web site (

22. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Petrified Trees
What clues could help us figure out what the environment might have been like when the dinosaurs roamed this area? (Rocks, fossils, etc.)
The surrounding sedimentary rocks are primarily siltstones, mudstones, and sandstones. Just up the hill, there are several large petrified tree remains. (Notice the yellowish fragments on the surface.) It’s estimated that they grew to around 100 meters tall. There are also several types of fern fossils in the pit.

23. Depositional Environment
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Depositional Environment
About 67 million years ago this area was not a desert, but rather the muddy margin of a small river. The paleoenvironment of this area suggests that we are working on the inside curve of the river. The tree fossils are piled up like there was a log jam. The dinosaur bones are scattered in piles on the point bar. (This view is from the top, center area of the ancient river at petrified log jam, looking toward the curved point bar where the dinosaur bones are being excavated.)
There aren’t many scratches on the bones. What does that imply? (Not much transport before burial).
One of the larger leg bones was discovered sticking straight up - maybe they got stuck trying to cross the soupy, muddy point bar. Maybe they got caught in a deluge, like a monsoon rain. What are your theories?

24. Late Cretaceous Diorama
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Late Cretaceous Diorama
This drawing shows one artist’s idea of how the area might have looked in the Late Cretaceous. It sure is different from the desert scene we see right now!
Captured from the National Museum of Natural History, Smithsonian Institution web site (

25. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Collecting the Data
The goal of this trip was to remove the fragile fossil bones from the field site to a safe environment where they can be studied. This pit had two rib bones, a vertebra, and a sacrum, part of the hip.
Again, the first step is to record the details of the how and where the bone was discovered. Why would that be important? (Reconstruction, paleoenvironment, etc.) We used the GPS to locate our position on the map and then took photographs of the bone in place, using a grid to show the size and orientation.

26. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Intact Samples
Sometimes the bones are in pretty good shape. In the case of this rib, we just cleaned out around the bone, identified each section with a marker, and placed the pieces in labeled bags.

27. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Fragile Samples
Unfortunately however, the bones are not always in such great condition.
What factors might damage the fossils over such a long period of time? (Ants, water, roots, decay, scavengers, etc.)
In order to get these bones out with as little additional damage as possible, we used plaster to “jacket” the bones. It’s just like putting a cast on the broken bones!
Here’s how we did it:

28. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Mixing the Plaster
… First, we mixed the plaster in a big bucket with the water we hauled in from camp.

29. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Preparing the Bone
… Then we dusted and sprayed it with water to get it clean and wet.

30. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Protecting the Bone
… The next step was to cover the wet bone with toilet paper - yes, plain old TP - to keep the plaster from getting on the actual sample.

31. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Plastering the Bone
… This part was really a bit fun. We dipped burlap strips into the plaster and pressed them all around the bone to form the hard, protective cast.
It didn’t take long for the top side to dry in the desert air, so we gently flipped the bone over and repeated the process on the bottom side.

32. Carrying it out of the Pit
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Carrying it out of the Pit
… Now the bone is ready to take out of the pit and into the lab for study. (This is a picture of Dr. Montgomery carrying the plastered rib out of the pit which was about 5’ deep.)

33. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Striking the Site
Since this was the last trip to dig this season, we had to “strike the site” before we headed home. All of the tools and equipment - even bottles of water - were collected and buried in the main pit. We covered the ground and made sure it would not be conspicuous; able to be plundered by unauthorized, uninformed personnel.
It was kind of sad, but we’ll be back soon and a few more months won’t bother the bones!

34. Carrying it back to Camp
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Carrying it back to Camp
… Then comes the real work! It’s really exciting at first, but it also gets really hard to carry all the bone samples across the desert to the van. All that plaster adds a lot of weight. But, it’s worth it in the end…

35. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Piecing it Together
All that is just the beginning of the business of digging dinosaurs.
Later, back at the camp, Dana emptied all the bags and started putting the puzzle together again. This is the rib we bagged. It looks a lot bigger on the camp table!

36. Consolidating the Sample
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Consolidating the Sample
To prepare these samples for the longer ride back to Dallas, she coated the pieces with a type of glue that would hold grouped sections together. This is called “consolidating the sample”.

37. Reassembled for Display
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Reassembled for Display
Dr. Montgomery had a special “sneak preview” of what they found this trip. You can see the large sacrum and another rib in the plaster case, in addition to the rib Dana consolidated.
A lot of time and detailed effort goes into creating the final museum displays. It may take over a year to thoroughly clean some of these samples. Skilled and patient specialists use smaller and smaller tools to pick off the debris. The last step is to blast them with very fine bursts of compressed air - kind of like the tools at the dentist’s office. Imagine how tedious all that detailed work would be to complete a skeleton the size of this room!

38. Reconstruction & Display
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Reconstruction & Display
Dinosaur Hall
This picture shows Dinosaur Hall in the National Museum of Natural History at the Smithsonian Institute in Washington, D.C. These bones have been cleaned and restored and researched to allow reconstruction of some amazing dinosaur skeletons.
The Dallas Museum of Natural History is preparing the bones from our dig. If you get a chance, stop by there. It’s the only working paleontology lab in this region. The museum has scientists and researchers on staff who excavate and put together all the pieces of the past. Located in the basement, the lab is in full view and provides a valuable learning tool for students and would-be dinosaur hunters of all ages!
The Dallas Museum’s Vertebrate Paleontology Collection houses approximately 7500 cataloged specimens that focuses on the south-central part of the United States. Specimens range in age from the Ordovician to the Pleistocene. The strength of the collection is in the later Mesozoic, particularly with respect to marine reptiles. See what you can discover right here in Dallas!
Captured from the National Museum of Natural History, Smithsonian Institution web site (

39. Speculating on Theories
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Speculating on Theories
There’s still a lot to be learned about our Alamosaurus and his life in the ancient Big Bend. After the day’s samples are prepared, Dr. Montgomery and museum workers discuss their theories in light of today’s discoveries and share ideas as a major part of the scientific process.
What do you think they might talk about? (Other finds, weather, next step, etc.)

40. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Dinner - finally!
Needless to say, we worked up quite an appetite that day and it was good to relax at camp. One of the greater rewards of field work is dinner… Everything tastes just a little bit better in the wild! (This is a picture of Chef Montgomery tending to a grill full of steaks!)

41. Rainbow over the Desert
Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Rainbow over the Desert
So ends another day in Big Bend country…
I hope you will each be able to experience the magic of this native land for yourself soon. If not, at least you have an understanding of what’s out there and hopefully an appreciation of what’s being done about it.

42. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
Sunset over the Desert
The desert is an interesting and exciting place full of life and adventure.

43. Virtual Field Trip:
A Day in the Desert Digging Dinosaurs
The End!