Author Archives: Greg

New evidence on the sizes of pterosaurs

The flying reptiles, pterosaurs, were an amazing successful group of prehistoric animals. They ranged from the Late Triassic through the end of the Cretaceous periods, a span of time of about 156 million years. That is over 2 times longer than the time since dinosaurs became extinct, and mammals have dominated the terrestrial landscape.

Pterosaurs were the first vertebrates to achieve powered flight, followed later by the birds and bats. However, during their hay-day, pterosaurs achieved an incredible range of diversity in form and size, and occupied countless niches within the Mesozoic world.

Interestingly enough, the first pterosaur remains to come from North America were found in Kansas. Flying reptiles had been known from Europe, but during an 1870 collecting trip through the western territories, O. C. Marsh stopped off in Kansas. Near the end of the trip he spotted a long, slender bone weathering out of the chalk formation, and collected what he could before heading back to Yale on the train. He thought the bone looked like the finger bone of the pterodactyls from Europe, but this bone was much larger. He estimated the wing-span to be 20 feet. The next year, he traveled back to collect the rest of the animal in the Kansas formation, and found that in fact his estimate of its giant size was correct. He named this new animal Pteranodon.

Greg dusts the life-sized models of Pteranodon sternbergii in the Sternberg Museum of Natural History

As more and more flying reptiles have been found in the fossil record, as basic question about them has puzzled scientists—how well could they fly? Estimating the body mass is a fundamental part of this inquiry. We can look at modern birds and see the constraints that flight dictates for body mass at least today. How do the pterosaurs compare?

In a recent publication, the question of body mass in pterosaurs is addressed (Henderson 2010). In the most detailed study yet of pterosaur body mass, Henderson set out to explore this question and to compare the results to birds. He created a model of body mass based on modern birds by creating digital, three-dimensional models of their bodies. His model was corrected for differences in density from different areas of the body. For example, the wings will have a different average density than the trunk, where the volume of the lungs greatly impacts its overall density.

Using birds, he refined his model to accurately calculate their masses and centers of gravity. Then, he turned to the pterosaurs. What he found was very interesting. The pterosaurs in his study ranged from less than an ounce for Anurognathus to an astonishing 1,200 pounds in mass for Quetzalcoatlus (more on this in a moment).

The giant pterosaur Hatzegopteryx compared to a modern giraffe. Illustration by Mark Witton.

The giant pterosaur Quetzalcoatlus northropi compared to a modern giraffe. Illustration by Mark Witton.

Excluding the giant Quetzalcoatlus for a moment, the other heaviest pterosaurs were Pteranodon at 41 pounds and Tupuxuara at 50 pounds. The estimates for the ancient fliers are not too far off the masses of the largest modern flying bird the Great Bustard, at 35 pounds. So, we know that it is at least possible for an animal of that weight to get airborne on a regular basis.

So, what about the giant Quetzalcoatlus? This animal is known from fragmentary remains from Texas where it was first found in 1971. While mostly known from fragmentary remains it is estimated that it had a wing span of 37 feet or more. Earlier estimates of the weight of this animal vary widely from 141 – 608 pounds. Henderson points out that many of the body mass estimates of the past were influenced by engineering constraints calculated for an animal with this great wing span to be able to fly. The thinking being that an animal evolved from flying animals most likely flew.

But, in an interesting twist, Henderson’s estimate is twice as much as previous estimates, so he turns the issue around and suggests the heresy that maybe giants like Quetzalcoatlus (and I would add Hatzegopteryx by extension) did not fly. Instead, it is perfectly reasonable to assume that a formerly flying species secondarily adapted to a fully terrestrial life style, growing to dramatic size as a protection from predation or for other similar advantage. We certainly can find examples of that in the modern birds too, in the flightless ratites, the emus and ostriches.

No doubt this issue will continue to be explored (for an alternative view see The largest pterosaurs have not been grounded yet) . That is the fun of science—keep probing and answers, and more questions, reveal themselves.

Henderson, D. M. 2010. Pterosaur body mass estimates from three-dimensional mathematical slicing. Journal of Vertebrate Paleontology 30(3):768-785.

Accurate Dinosaur Toys

If your kids are fascinated by dinosaurs, and many are, you might like a recommendation on some of the best dinosaur toys out there. Being a paleontologist and museum professional for many years I do have some experience with quality dinosaur models.

Without a doubt some of the best and most accurate models you can get for dinosaurs and other prehistoric animals are from the Carnegie Collection. A number of features of these models, produced by Safari, make them highly recommended.

First, most of the models were sculpted to the same scale, 1:40. This means that almost all the models can be directly related to each other, so you can easily compare the size of a Brachiosaurus with an Apatosaurus, for example. Not every model is the same scale however, so you do have to watch that as it could be misleading.

Sauropod dinosaur models from the Carnegie Collection. Left to right are Camarasaurus, Diplodocus, Brachiosaurus, and Apatosaurus.

Another significant thing about the Carnegie dinosaur toys is that they are all hand painted, meaning that there are no two models that are identical. Each one is a bit different and special.

Finally, the models have been in production since 1989, and they add new species to the series almost every year. Some species from the series are retired from the line, meaning they are no longer available commercially, which might give them some collector appeal. And occasionally species already represented in the series are re-sculpted based upon new scientific evidence about their appearance or mode of life.

Various dinosaur models from the Carnegie Collection. Back row, left to right, Spinosaurus, Kronosaurus, Plesiosaurus, Deinosuchus, Tyrannosaurus. Front row, left to right, Allosaurus and Pteranodon.

The Carnegie models are some of the most accurate dinosaur toys on the market today, and we use them regularly in our museum education programs. If you are looking for some great models, these are hard to beat.

Pick yours up at the Boneblogger store. Look in the recommended section.

Advice on Installing Travertine Tiles

Tiles come in a wide variety of materials. No matter what material is chosen, installation has these basic steps. One of the first requirements is a solid and firm base. A mastic or mud bed is spread on the firm base to hold the tile in place. The tiles are then laid on the mud to form the desired pattern. The mud is allowed to dry before a grout is spread to fill the spaces between the tiles. A sealer is applied to the entire area to prevent discoloration of the grout and the tile.
The above statements apply to all forms of tiles. Installing travertine follows the regular rules plus a few that are specific to a natural stone and a veined material.

One of the considerations when working with travertine tile is the veining of the stone. A commonly used method of shaping man-made tiles is by using a “score and snap device”. This method does not work with travertine. The natural travertine is porous, and may have those pores filled with a special mixture of cement and epoxy. The combination of the stone and filler gives the tile an irregular density that requires a power tool to cut the tile. The veins that run through the travertine add another complication for the installer. The veins are a natural “weakness” lines in the stone. Cuts can be made across the veins, but experience working with travertine will help guide a installer to prevent unwanted breaks both at the time of setting and later.

Black Rock travertine

The tiles are cut from natural stone. The stone will vary from quarry to quarry and cutting results in some irregularities in the thickness and shape of the tiles. Most of the irregularities can be adjusted by the way the tile is laid. Again, an experienced tile setter will adjust the mud bed to compensate for variation in thickness, and can position the tiles to conceal the size differences.

Because the stone is a natural product and no two tiles will be the same, the coloration in the stone will vary a great deal. Some of the tiles will have many veins and others little or none. It is highly recommended that you open and inspect all the boxes of tiles to allow the installer and the homeowner to view the stone and lay out a pattern that is most pleasing. This will also allow the installer to select the best tiles to cut before the job is started. This could save time and money because fewer tiles are ruined. In many cases laying out the whole area will be well worth the time.

Most installers feel that sealing the tile is a must. Sealing the stone is a simple way to assure the tile will remain beautiful. Re-sealing the tile every few years is also recommended. The routine care and maintenance is best done with clear water.

Mild soaps can be used but harsh cleaners and acids should never be used. The calcium carbonate of the travertine will react with even weak acids and dissolve. This will cause the stone to etch and could cause significant and irreversible damage. If you are uncertain you can test any cleaner on a sample tile reserved for that purpose before you use anything on the installed tiles.

My National Geographic moment

“A photographer from National Geographic wants to talk to you.” These words, or words to those effect, met me as I came into the museum office one day back in 2001, and they definitely caught my attention.

It was 2001 and I was Assistant Director of the Sternberg Museum of Natural History. We had just reopened the museum in its new location in Hays, Kansas, a few years before in 1999. The museum had enjoyed some tremendous success at attracting visitors and media attention from across the state. And now someone from National Geographic wanted to talk to us? Wow. I returned Jonathan Blair’s call and began an unusual week of activity.

It turns out that the magazine was going to run a story on pterosaurs, the flying reptiles from the Mesozoic, and they hired Jonathan to get pictures to illustrate it. He had already traveled to some of the great museum collections for pterosaurs in Europe and the United States, but he wanted to visit Sternberg. The Sternberg’s collection of pterosaur material is about the third or fourth largest in the nation, and very significant.

The Sternberg Museum, on the campus of Fort Hays State University, was managed for many years by George F. Sternberg, famed fossil collector. He spent his free time out in the chalk, the Niobrara Formation of western Kansas, collecting the fish and swimming and flying reptiles that left their remains millions of years ago. Sternberg supplemented his salary at the museum by selling specimens to other museums, but if he collected something really nice it went into “his” museum. Over the years, the museum’s collection grew in size and quality.

Besides our amazing collection of fossils, Jonathan had heard about our life-sized pterosaur models we had just installed in our walk-through Cretaceous exhibit. And he had a crazy idea—let’s take a life model of the beast and “fly” it over the very rocks where its remains can be found. He wanted to take one of our life-sized model and photograph it over the chalk beds.

Well, I can bend over backwards for National Geographic, but taking one of our brand new models down from the ceiling, which had not been easy to install in the first place, and which since had walls built up around them, and truck them 70 miles to hang from a crane in the chalk sounded a bit risky to me.

But I did offer to help in any way we could, so I did the next best thing—I found him another pterosaur model.

Over the next several days we made plans and preparations for the big event. We needed to get the model that I was able to find shipped to the museum. It had been kept in storage and was a little beaten up, but the company that supplied it sent a staff member to clean, fix it, and touch up the paint for its big moment. The model, being life-sized, had a twenty foot wing span, flimsy neck with a large head at the end, and feet that stuck out the back, giving the whole thing a cross shape, making it too long in any direction. Not exactly the easiest thing to get into a truck and ship!

We scouted a location for the big photo shoot. I took Jonathan to the Castle Rock area, a well-known outcropping of the chalk that has easy access and grand vistas. We needed to secure special permission as we were going to bring in a crane and another truck to transport the pterosaur model.

We needed to arrange for a crane to make the 70 mile one-way trip from Hays to the chalk beds. On this, and on so many other occasions, I marveled at the “can do” spirit of western Kansas people. You want something done just ask a former farm kid. While he might look at you funny, he will get it done.

In between all this activity, I remember some spectacular meals shared with Jonathan, listening to his many adventures from around the world while taking photographs. He also shot pictures around the museum, and he took a couple of photos of me that I have cherished ever since.

Greg dusts the life-sized models of Pteranodon sternbergii at the Sternberg Museum of Natural History. Photograph by Jonathan Blair.

The big day arrived and all was going well. The weather cooperated, the truck was loaded with its ungainly cargo, and the crane made it to the site. We had also brought along a number of crew members to help hold the model. We wanted to lift it into the air for the photograph, but if you know anything about western Kansas, you know it is windy. I was not sure what would happen when you lifted such a thing into the gusty winds, and how hard it might be to control. The only control we had were guy-wires coming down from the wing tips to hold it against unruly behavior.

With trepidation we gave the signal to the crane operator to lift, and the hundred pound model took to the air. And in the end, the wind was no issue—the model, like the animal it represented, was built for the air. It found a comfortable equilibrium and settled into the wind easily. Jonathan snapped his pictures, and just like that we had what he had come after.

Life-sized model of a pterosaur, an ancient flying reptile, soars onces again over western Kansas

Life-sized model of a pterosaur, an ancient flying reptile, soars once again over western Kansas

We took more photos at a few other locations, all of which could have made fantastic desktop images, but he knew he was done. We packed up and came home, and all those days preparation resulted in the lead image for the story. It was all Jonathan’s photo and idea, and I enjoyed the part I played in making it happen—one of the perks for working at a museum.

See the National Geographic story.

Jonathan Blair’s web page

Spending time in Purgatoire

One of the many places that I have been fortunate to spend time in is Purgatoire. Perhaps not the same thing you are thinking, but I am referring to the Purgatoire River Canyon in southeastern Colorado. Located south of La Junta, this area is an often-overlooked gem. The scenic vistas could be used for your desktop wallpaper!

Purgatoire River Canyon in southeastern Colorado

The many names applied to the region can be confusing. The Purgatoire River has cut a dramatic canyon in this part of the plains, and with the Rocky Mountain Front Range far to the west, it can be almost startling to come upon the deep canyon in an otherwise rolling plains landscape. Anglo settlers bastardized the name of the river, and instead of the eloquent Purgatoire, ended up calling the area Picket Wire, so both names alternately apply.

The area is managed predominately by two federal agencies, the United States Department of Agriculture’s Forest Service and the Department of Defense through the Army. The military uses their lands for maneuver practice, as I understand it, tanks and other mechanized equipment. Some years ago the Army carved off some of their land and gave it to the Forest Service to manage as part of the Comanche National Grassland. The Forest Service land is used for recreation and also the preservation of significant historic and prehistoric resources.

Petroglyph of human and horse figures

Rourke Ranch house in the Purgatoire Canyon

The historic resources include Native American petroglyphs and other archeological sites, early Spanish homestead sites and churches, early American homesteads. The prehistoric resources include dinosaurs and other prehistoric animals, both body fossils and trace fossils. I was very fortunate to have been involved in the documentation of some of the first dinosaur fossils from the region (Schumacher and Liggett 2004).

Dinosaur trace fossils, in particular dinosaur tracks, are well preserved in one section of the Morrison Formation in the bottom of the canyon. These tracks were discovered in 1935 by a young girl as can be seen in this newspaper clipping from the Topeka Capital Journal. However, the tracks are most definitely not those of a Tyrannosaurus rex (mentioned in the clipping) as that beast did not stalk the Earth for at least 90 million years after the track-makers walked here. This track site is the largest continuous track site of dinosaurs known from North America, and contains over 1,400 prints.

Newspaper clipping announcing the discovery of the Purgatoire track site

However, because of the remoteness of the site, scientists turned their attention to other dinosaur tracks found in Texas, and the Colorado tracks were essentially forgotten for many decades. However, a newer generation of scientists have re-examined the track site. Of interest is the fact that the site shows five parallel sauropod tracks, suggesting that at least in this case, the animals walked along together spread out, not walking in a line (Lockley 1991).

There are actually several track layers in the rocks. Also preserved are several three-toed theropod, or meat-eating dinosaur. While it is difficult to exactly match the track to the species of dinosaur that made them, the large sauropod tracks were made by an animal like Apatosaurus (Brontosaurus of old) and the meat-eating tracks are similar to what an Allosaurus would make.

A well-preserved theropod dinosaur track in the Purgatoire Canyon

View of the Purgatoire River track site using low altitude photography

In addition to the tracks, the canyon is also now yielding body fossils of dinosaurs. It is really no surprise since the Morrison Formation is extensively exposed along the river canyons. The Morrison is the name given to a wide-spread formation that is the most prolific producer of Jurassic dinosaurs in North America. The formation outcrops in North Dakota, South Dakota, Montana, Wyoming, Colorado, Oklahoma, Texas, New Mexico, Arizona, Utah, and Idaho. Every Jurassic dinosaur you have ever heard of comes from the Morrison; animals such as Allosaurus, Apatosaurus, Diplodocus, Stegosaurus, and Camarasaurus all come from this formation. (See Formations for information about what that means.)

Stratigraphic section of the Purgatoire River Canyon showing the geologic formations that outcrop

Given the Purgatoire River’s remoteness, and the fact that it was controlled for many years by the Army, few people were able to explore the region until more recent decades. Thus, now it is one of the last areas of the Morrison Formation exposures to be explored. And it is proving to be as rich as expected.

Over the last decade, the Forest Service has been conducting Passport in Time (PIT) programs in the canyons, looking for new dinosaur sites, and excavating sites. Many people, scientists, graduate students, and the lay public have enjoyed excavating dinosaurs in this beautiful and remote canyon. And several significant specimens have come out of the area. The Forest Service has partnered with many museums from the region to study this treasure-trove and to allow people to enjoy this amazing region.

Volunteers excavate dinosaur fossils from the Woody site

Dinosaur vertebra from the Woody Site being prepared at the Sternberg Museum of Natural History

Plastered dinosaur bone being carried out of the LC Site

Volunteers excavate dinosaur bones from the Morrison Formation at the LC site

The Forest Service offers tours of the canyon and track site. If you are interested contact the Forest Service Office at 1420 East 3^rd, La Junta, CO 81050, 719-384-2181. If you plan to visit the area on your own, be aware of a couple of things. You cannot drive into the canyon without prior authorization. You can hike in on your own, but it is several miles in and out, and the summer temperatures can be brutal, so bring plenty of water and plan accordingly.

A large section of Dakota Formation slumping away from the main block provides a dramatic hiking experience

Lockley, M. G. 1991. Tracking Dinosaurs: A New Look at an Ancient World. Cambridge University Press, New York.

Schumacher, B. A., and G. A. Liggett. 2004. The dinosaurs of Picketwire Canyonlands, a glimpse into the Morrison Basin of southeastern Colorado. Journal of Vertebrate Paleontology 24(Supplement to 3):110A. (Poster page 1 and page 2).

Many other dinosaur facts can be found here at Boneblogger. Just search or select the category.

Boneblogger: Science and the outdoors

Exploring the natural world