Tag Archives: Kansas

Fossil tells a new tail

Mosasaurs lived in the world’s oceans during the Late Cretaceous, the last Period from the Age of Dinosaurs (see the geologic time scale). They are close relatives of modern snakes and lizards, and during the Cretaceous they become fully aquatic sea monsters, growing to tremendous sizes, and were the top predators of their environments.

Their fossil remains occur in great numbers in the marine chalk deposits of the Central Plains, and numerous specimens have been preserved in museums all over the world (see posts on the chalk formation and on rock formations in general). Yet despite the great numbers of specimens collected, we still have much to learn about these great beasts.

For example, examination of their bones shows that they are elongate animals, with enlarged tails for propelling their bodies through the water. Their limbs are modified into flippers, useful in controlling the direction and orientation of their bodies in the fluid medium. So, it is clear that they are primarily tail-swimmers.

Early restorations based upon this evidence imagined a tail sort of like a modern crocodile, a thick tail that was slightly compressed laterally, making it taller than thick, but remaining relatively snake-like. Early restorations of the skeleton articulated the tail as a long chain of vertebrate, continuous from base to tip without any remarkable difference along the way.

Here is an illustration of the skeleton of the mosasaur Platecarpus from a classic work on mosasaurs (Williston 1898). Note the rod-like straightness of the back.

Mosasaur Platecarpus from Williston

Mosasaur Platecarpus from Williston

And here is an artist’s illustration of Tylosaurus, the largest of the mosasaurs, from Mike Everhart’s Book, Oceans of Kansas, showing the tail with a slight thickening near the end, but mostly being straight (Everhart 2005, recommended in the Boneblogger store).

Mosasaur Tylosaurus

Mosasaur Tylosaurus from Oceans in Kansas by Mike Everhart

However, frequently the skeletons of mosasaurs were found preserved in the rock with the last third of the tail bent downward, away from the main axis of the base of the tail. And this was not just found in a few skeletons, but it was found frequently enough that scientists speculated, at least in conversations with each other, that perhaps the down turned tip was not an artifact of preservation, but maybe meant something.

Well, a newly described mosasaurs fossil, which has exceptional preservation, provides the answer. This specimen collected in Kansas and now at the L.A. County Museum, preserves not only the bones, but also impressions of skin, impressions of internal organs, and even some of the body outline. The bones of the tail are clearly down-turned, giving the authors of this new study enough confidence to state what has been quietly talked about before—mosasaurs had a bi-lobed tail fluke (Lindgren et al. 2010).

Mosasaur Platecarpus

Mosasaur Platecarpus showing revised body outline

It only takes a single fossil to help overturn past notions about prehistoric life. The next big discoveries are out there, in the rocks and sitting in the museum drawers, waiting to be examined in detail. What will we find next?

Everhart, M. J. 2005. Oceans of Kansas: A Natural History of the Western Interior Sea. Indiana University Press, Bloomington.

Lindgren, J., M. W. Caldwell, T. Konishi, and L. M. Chiappe. 2010. Convergent evolution in aquatic tetrapods: insights from an exceptional fossil mosasaur. PLoS ONE 5(8):e11998.

Williston, S. W. 1898. Mosasaurs. University of Kansas Geological Survey 4(1):81-347.

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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

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.

Related Posts:
Formations
Niobrara Chalk
My National Geographic moment

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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 in the Sternberg Museum of Natural History

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

Related Posts
Geologic Formations

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Fossil ‘discovery’ rewrites history

Originally published in the Hays Daily News 21 February 2010

By MIKE CORN
mcorn@dailynews.net

For nearly 40 years, it’s been tucked away in a storage room at the University of Kansas, little more than a bag of bones that at the time it was collected struck even the most experienced as unusual.

The late Marion Bonner was right: The discovery in 1971 by his son Chuck then 21, was indeed unusual.

On Thursday, scientists announced that it was deserving of its own genus, proving to be something of a missing link between the oceans of 100 million years ago and today.

The announcement was made Thursday in Science Magazine.

The fossil, representing a massive filter-feeder much like the blue whale of today, was named Bonnerichthys, in honor of the Bonner family — responsible for outstanding fossil discoveries in the chalk bluffs of northwest Kansas.

Several of those discoveries are on display at Sternberg Museum of Natural History, as well as other museums.

The Bonnerichthys discovery came not from a recent collection, but from one that Chuck Bonner discovered in 1971 in Logan County while on a fossil-collecting expedition with his family.

“That was pretty nice,” Bonner said Friday. “Pretty nice to have a genus named after us.”

Several individual species have been named for Marion Bonner, who collected fossils alongside George Sternberg, founder of the Sternberg Museum.

While it was discovered by Chuck Bonner, the excavation work fell to his father.

“Dad knew when he was digging on it, it was something different,” Bonner said.

“I tell you what, I wasn’t too excited that day. Actually, I was more excited about Dana finding a turtle up above me.”

While the Bonner discovery — once it was cleaned up — was responsible for the naming of a new genus, there’s another and more complete specimen being prepared.

That discovery, coming from land owned by Mahlon and Carolyn Tuttle, has been donated to Sternberg and will provide even richer detail about the fish.

The Gove County specimen was discovered by Kenshu Shimada, an FHSU alumnus now at DePaul University in Chicago, and excavated by Mike Everhart, adjunct curator of paleontology at Sternberg.

Everhart has been thrilled with the credit given to the Bonner family, as well as the fossil that was collected in Gove County.

The trouble with plankton feeders is they are too much like sharks, in that they have little skeletal structure to fossilize. Much of it is cartilage and tissue.

Bones in the skull, for example, were connected by cartilage.

That made it big, but difficult to find, 100 million years later.

“It is the biggest bony fish feeding in the Cretaceous sea,” Everhart said. Generally, the Kansas variety, which makes up the largest percentage, would have been about 30 feet long.

The discovery, that it was a huge fish that fed on plankton, “filled in the blanks.”

Early on, the fish had been classed as a swordfish, but neither sword nor skull had been found.
Everhart said they have now determined that the fish lived from 170 million to 85 million years ago, dying out at the same time the dinosaurs.

“At the end of the Cretaceous, for some reason, the plankton died off,” Everhart said. That spelled doom for the filter feeders as well.

The chain of events have thrilled Everhart and Bonner.

“It’s very exciting to me,” Everhart said of the discovery and its publication in Science Magazine. “It’s not everyday you get a chance to be published in Science. It’s a pretty prestigious publication.”

Determining the fish was a filter feeder was just as significant.

“It was just an ‘aha’ moment,” he said. “We figured out what was going on.”

“He would have been swelling with pride,” Bonner said of his father.

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What is paleontology

What questions fall within the purview of “Paleontology”?

Quite a wide variety, it turns out, because paleontology is the study of prehistoric life – the exploration of the entire history of life. Since 99.9% of all species that existed are now extinct, that is a lot of biodiversity. The science is multifaceted and diverse because the topic is equally diverse.

Because of the connections with geologic time and rock formations as the context of fossils, most paleontology classes are offered through geology programs at universities. I LIKE teaching introductory courses in geology because I find that people frequently end up taking geology in college as a last resort. Students generally are required to take a science class with a laboratory and they too frequently review their options without much enthusiasm. They took biology in high school and did not like it then, so want to stay away from that now. Chemistry and physics sound like a lot of math, so that leaves geology, they reason.

Fossil collecting in western Kansas. A partial mosasaur skeleton is visable in the middle foreground.

Fossil collecting in western Kansas. A partial mosasaur skeleton is visible in the middle foreground.

On the first day of geology class I like to point out that the study of the Earth and its history involves biology, chemistry, and physics, so we will cover them all. There is usually a little moan from the class at this, and I enjoy my moment of sadism. Paleontology in particular incorporates biology and geology to a very high degree, because to study fossils you have to fully understand the animals as well as the history that you can read from the rock record.

So could we come up with a classification, not of fossils, but of paleontologists?

Since the topic is so multifaceted the science falls naturally into several key areas. For example, individual paleontologists tend to be more oriented toward either geology or biology. The first group might be more interested in the animals themselves: how did they live; how did they move and capture prey; how did they relate to other organisms in their environment.

The second group might be more interested in what the animals can tell them about the Earth’s history: what do the fossils tell us about the movement of plates over the Earth’s surface through time; when did different animals live in geologic time so we can estimate the age of rocks; that sort of thing.

Of course, this is an over simplification.

Paleontologists can also be classified by which group of organisms they work with. Is it plants (maybe fossil forests made of ferns), or invertebrates animals — marine or terrestrial – ranging from the largest squid ever known to fossil spiders, or maybe vertebrate animals.

A lot of the people I know are paleontologists, and they tend to be people with diverse interests, often ending up doing a bit of all of it. For example, many years ago I worked on a fossil locality in southwestern Kansas that included plant, invertebrate, and vertebrate fossils. Having all the groups of organisms was critical to interpreting a much fuller picture of the ancient environment there than any one of the groups alone could have provided.

As a paleontologists I must be a “jack of all trades,” and that is one of the things I love most about it.

Other interesting facts can be found here at Boneblogger. Enjoy.

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