Tag Archives: O. C. Marsh

Two dinosaurs become one

Earlier this year a paper was published (Scannella and Horner 2010) on one of the most well-known dinosaurs of the Late Cretaceous, Triceratops, updating our understanding of not only this dinosaur species, but also maybe influencing our view of many other dinosaur species as well.

Triceratops

Triceratops as mounted at the Carnegie Museum of Natural History

Triceratops was first described in 1889 by O. C. Marsh, and has become one of the best represented dinosaur species in terms of numbers of fossils recovered. Their remains are very common in the Hell Creek Formation of Montana and the Dakotas. And, Triceratops has been known by practically every kid for the last 100 years, being well represented in dinosaur movies and dinosaur toys the world over.

Triceratops is best known for its three horns and neck frill of bone. Torosaurus, another dinosaur that is obviously related to Triceratops because of its similar appearance, was also first named by Marsh in 1891. It is found in the same geologic units in the same region, but is much less commonly found. Torosaurus was much larger than Triceratops, and had large openings in the neck frill, and its horns pointed more anteriorly.

So, for over 100 years paleontologists thought there were at least two species of horned dinosaurs in these beds. But scientific understanding makes progress. In the early “bone rush” days of the nineteenth century the game was naming new species. Today, there is a trend of relooking at those species to see if they are in fact different.

Torosaurus

"Torosaurus" mount at the Milwaulkee Museum, now should be called Triceratops.

This is where the new study comes in. The authors examined Triceratops and Torosaurus and questioned whether they might not be the same species, but at different life stages. It has become apparent that individuals of a species can change a great deal over their lifetimes. A newborn human does not look much like an adult in body proportions, for example. If past species also changed significantly over their lifetimes, the different stages could easily be mistaken as completely different species. And that seems to be the case here.

By looking closely at the trends of skull shape and indicators of maturity, Scannella and Horner believe that in fact Torosaurus individuals are older and more mature individuals of Triceratops. This means that later in their development individual Triceratops specimens changed significantly as they reached maturity, developing the large openings in the neck frill and increasing in overall size.

The implications for other dinosaur species are clear. If individuals can change dramatically during their lifetimes as they mature, perhaps there are many named dinosaurs that are not truly different and unique species, and we need to match youngsters with adults. No doubt this will keep paleontologists busy for the next 100 years.

And in case you are worried, the name Triceratops will remain, since it was the first name given to the species that we now realize includes those individuals that one were called “Torosaurus.” So, despite some headlines Triceratops did (and still does) exist!

Scannella, J. B., and J. R. Horner. 2010. Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30(4):1157 – 1168.

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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.

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Dinosaurs dragging their bellies—Huh?

Isaac Newton famously wrote in 1676,“If I have seen further it is by standing on the shoulders of Giants.” This gets to the heart of the scientific process—a gradual addition and refinement of human knowledge and understanding of the natural world. But, of course, sometimes even giants had wacky ideas.

The particular “giant” to whom I refer is Charles H. Sternberg, famed fossil collector. Sternberg began collecting fossils when he was seventeen, at a time when it was not exactly commonplace, in about 1867. And he dedicated his life to this unusual pastime, founding a family of fossil collectors when his sons continued the tradition for a second generation. Together, the Sternberg family collected a huge number of fossils for museums and science. There is hardly a major museum in the world that does not have one of their discoveries on display.

Sternberg started his career in the hills of western Kansas, collecting fossil plants from the Dakota Formation. He sent his specimens back to the young Smithsonian Institution, for which he received a letter of acknowledgment that he treasured his whole life. He was bitten by the “fossil bug.”

Edward and Charles Sternberg

A rare photograph of Charles Sternberg (right) with his twin brother Edward (left).

By 1875, he enrolled in college where he studied briefly under Benjamin Mudge. Mudge organized a fossil collecting trip for 1876 to collect for O. C. Marsh, the Yale College paleontologist. Sternberg was too late to sign up with Mudge, and bitterly disappointed, and somewhat brazenly, he wrote a letter to Edward D. Cope, Marsh’s rival.

Sternberg wrote, “I put my soul into the letter I wrote him, for this was my last chance. I told him of my love for science, and of my earnest longing to enter the chalk of western Kansas and make a collection of its wonderful fossils, no matter what it might cost me in discomfort and danger. I said, however, that I was too poor to go at my own expense, and asked him to send me three hundred dollars to buy a team of ponies, a wagon, and a camp outfit, and to hire a cook and driver. I sent no recommendations from well-known men as to my honesty or executive ability, mentioning only my work in the Dakota Group.” (Sternberg 1909, pg 33).

Sternberg anxiously awaited a reply, and when he opened Cope’s letter, a draft for $300 fell out, a very significant sum. So began his professional fossil hunting career. Over the years he collected throughout the American and Canadian west. In the twilight of his career he semi-retired to San Diego, and was allowed to use the title of curator at the natural history museum.

Museums and libraries are marvelous places, full of fascinating treasures. It was while reading in the archive at Fort Hays State University’s Forsyth Library that I came across a carefully saved clipping of an article from the  Los Angles Time Sunday Magazine from December 20, 1931, titled “The habits of dinosaurs,” written from an interview with the 80 year old fossil collector.

In the article, Sternberg is quoted as giving his vision of the life of some of the dinosaurs that he had collected over the many years. While I recognize that it is not really fair to judge the views of earlier experts, especially with the perspective of almost three quarters of a century of additional knowledge, but it can be damn funny.

Sternberg is quoted as authoritatively saying, “Dinosaurs were lizards. They stood and walked like lizards, not like elephants or rhinos. That is to say, the normal positions of their feet were outside the line of the body, just like the alligators of today, not inside or even with the line of the body, as are the feet of horses, elephants and other mammals. Moreover, the dinosaur, instead of standing up, on straight legs, as usually pictured, bent its legs outward, as do the lizards, and dragged it belly on the ground, again like the alligators, monitors and other large lizards of the present day.”

Dinosaur reconstructions of that period typically showed dinosaurs with spindly, lizard-like limbs, and tails dragging, but with a generally upright posture. Sternberg evidently did not agree, arguing in favor of his views with some odd reasoning.

Citing fossils of preserved dinosaur skin, he said, “Furthermore, the skin on the lower side of the abdomen of this dinosaur was much thinner and more delicate than on other parts of the body. This is further and strong argument for my claim that the dinosaur dragged its belly on the ground, as do the alligators of today, which so protect their vital parts from carnivorous animals…you may be sure that no tender-stomached dinosaur, whether it weighed forty tons or forty pounds, would voluntarily expose its tenderest and most vital parts to attacks by the tyrant dinosaur or any other carnivorous creature by walking erect.”

Illustration from Los Angles Times Sunday Magazine, 1931

Illustration from Los Angles Times Sunday Magazine showing Sternberg's idea of dinosaur stance.

I totally agree. I hate walking around with my “tenderest” parts exposed. The accompanying illustration of Sternberg’s vision of the Mesozoic is hilarious, with giant sauropod (long-necked) dinosaurs hunkered down, presumably guarding soft spots. I am not really sure how Sternberg expected it would work for a forty ton animal to push itself along the ground with its legs sprawled out to the side, much less how it would support its own weight on its chest, but details, details.

Even though the article claims that Sternberg was a “man of facts and not fancies,” he was prone to exuberant musing about the prehistoric beasts he collected. While he could be wacky, we owe a great debt to the entire family for their contributions to science.

Further reading about the Sternberg family:

Everhart, M. Oceans of Kansas website, summary of the work of Charles H. Sternberg.

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

Liggett, G. A. 2001. Dinosaurus to Dung Beetles: Expeditions Through Time, Guide to the Sternberg Museum of Natural History. Sternberg Museum of Natural History, Hays, Kansas.

Rogers, K. 1991. The Sternberg Fossil Hunters: A Dinosaur Dynasty. Mountain Press Publishing Company, Missoula, Montana.

Sternberg, C. H. 1909. The Life of a Fossil Hunter.

Other interesting dinosaur facts are found here at Boneblogger. Search or select the category for more.

Sternberg, C. H. 1917. Hunting Dinosaurs in the Bad Lands of the Red Deer River Alberta, Canada. Charles H. Sternberg, San Diego.

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Giant Short-Faced Bear: a Northern California Original

In 1878, James D. Richardson explored Potter Creek Cave in Shasta County, California. He found the skull of a bear beneath several inches of cave dirt, and he sent the specimen to Edward D. Cope, who determined that it was the type specimen for a new species of American “cave bear” (Cope, 1879).

Arctodus

Reconstruction of the Giant Short-faced Bear, Arctodus

When a scientist studies an animal and determines that it is something new to science, they set up a name for it and designate a type specimen. The type specimen, or type, holds a special significance as the “name bearer” for the entire species, and subsequent investigations of that species make reference to the type. They are often kept in special collections within the museums that hold them, or at least given special protection over other specimens. For example, they often are not loaned out as other specimens in the museum collection might be, so there is less risk of damage. (For a description of geologic type sections, see formations).

All too often the type specimens of fossil species have been based on fragmentary material or poor descriptions, making a full understanding of the species more difficult. A famous example of this is the story of the dinosaur Apatosaurus.

Apatosaurus was named by Cope’s rival, O. C. Marsh (Marsh, 1877). Both Cope and Marsh were rushing to describe more fossil species than the other, and their famous rivalry led to shoddy work by both men on occasion. Marsh said the type specimen of Apatosaurus was a “nearly complete specimen in excellent preservation.” However, he only briefly described the vertebrae of this new animal in his haste to publish the new name.

Later, Marsh published the name Brontosaurus, with a few comments on the pelvis and vertebrae of that type (Marsh, 1879). Brontosaurus soon became widely known to the public, and to many, represented the quintessential dinosaur. However, by 1903 Elmer Riggs recognized that Apatosaurus and Brontosaurus were in fact the same species of dinosaur, and since Apatosaurus was named two years before Brontosaurus, that name had priority and was the name that should be used (Riggs, 1903). However, the old name Brontosaurus was in such popular usage that it took many decades for the public to catch on. Now, it seems that every young dinosaur buff knows of this name change and is comfortable with it.

Since the first Short-faced Bear fossil to be recognized in North America was from Northern California, the type specimen, and the name of the bear, Arctodus simus, will be forever linked to the region. This “American Cave Bear” is now known from over 100 localities from Alaska to Mexico, east coast to west (Richards et al., 1996). It was a wide-spread species of the late Pleistocene Ice Age.

What is perhaps most striking about this bear is its size. Arctodus is the largest mammalian carnivore ever discovered. It is larger than any of the modern bears, tigers, or lions by a significant degree. An estimate for the largest Arctodus found to date suggests that if the individual was “lean” it weighed from 1,300 to 1,400 pounds (Nelson and Madsen, 1983). In contrast, a male lion weighs about 450 pounds. (See How big was the GSFB?)

So this imposing carnivore of the Ice Age roamed across North America, and the North State can forever claim it as its own. A full skeletal mount of this beast can be seen in the new Gateway Science Museum at Chico State.

COPE, E. D. 1879. The cave bear of California. American Naturalist, 13:791.

MARSH, O. C. 1877. Notice of new dinosaurian reptiles from the Jurassic Formation. American Journal of Science, 14:514-516.

MARSH, O. C. 1879. Notice of new Jurassic reptiles. American Journal of Science, 18:501-505.

NELSON, M. E., AND J. H. MADSEN, JR. 1983. A giant short-faced bear (Arctodus simus) from the Pleistocene of northern Utah. Transactions of the Kansas Academy of Science, 86(1):1-9.

RICHARDS, R. L., C. S. CHURCHER, AND W. D. TURNBULL. 1996. Distribution and size variation in North American short-faced bears, Arctodus simus, p. 191-246. In K. M. Stewart and K. L. Seymour (eds.), Palaeoecology and Palaeoenvironments of Late Cenozoic Mammals: Tributes to the Career of C.S. Churcher. University of Toronto Press, Toronto.

RIGGS, E. S. 1903. Structure and relationships of opisthocoelian dinosaurs. Part
1: Apatosaurus Marsh. Field Columbian Museum, Geological Series, 2:165-196.

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