Category Archives: Paleontology

What’s the value of a fossil?

I have the privilege to work as a professional paleontologist. Many people are excited by fossils and beasts from the past, and the media loves to cover new discoveries. Periodically, a friend will ask if I had heard of the latest fossil find being discussed by the media, almost always touted as the latest, the greatest, the biggest, or the best example of whatever. With genuine enthusiasm my friend will ask how thrilled I am about it. While I really appreciate their eagerness for me and my profession, when the fossils were collected by someone hoping to sell them I have to say, no, I am not really excited about the find.

My friend will usually blink a few times, trying to understand how I could feel that way. How can I help them understand why academic paleontologists are not excited by such specimens? Why if I have dedicated my career to learning about life of the past would I not even be interested in seeing such fossils? Wouldn’t all scientists be falling over themselves with glee to see these treasures? No.

The latest example is the so-called Dueling Dinosaurs from Montana, and much has been written about them, a meat-eating and a plant-eating dinosaur found together, promoted as having died in mortal combat. But these fossils are simply the latest example in the long-standing conflict between science and the commercialization of fossils. The key to easily understanding this conflict is to understand the two very different ways of appraising the value of a fossil: commercial and scientific.

We are immersed in the commercial value of things. Everything has a price. All around us in everyday life we see prices placed on goods and services. We are so comfortable making judgments about the monetary value of items we even have game shows like the Price is Right where we compete with each other to do so.

Additionally, we are familiar with collectors of all types. Art collectors, people who collect baseball cards, or old bottles. We occasionally hear of a rare collectable item selling for high prices, and fossils seem like they could be in that same category of potentially valuable collectable items.

“Sues skeleton” by Connie Ma from Chicago, United States of America – Sue, the world’s largest and most complete dinosaur skeleton.Uploaded by FunkMonk. Licensed under CC BY-SA 2.0 via Wikimedia Commons

High-profile fossils have occasionally been valued at very high market values. The Tyrannosaurus “Sue” sold at auction for over 8 million dollars. Recently another similar dinosaur was to be sold for over a million. The sellers of the Dueling Dinosaurs are reported to want 7 to 9 million. And the implication is clear—you can get rich on dinosaurs.

In our market-based society it is easy for non-scientists to think that market value must be the same as scientific value. High-dollar fossils must be worth more to science, right? This equivocation, however, is false.

To appraise the market value of a fossil you have to know what a willing buyer will pay a willing seller under current market conditions.

The scientific value of a fossil is very simply its ability to add to existing knowledge. To appraise the scientific value one needs to know about all the research that has taken place to date, all the specimens currently known to science, and an individual fossil’s potential to tell us something we didn’t already know.

The issue hinges on the fact that for a fossil to have high scientific value we must be extremely confident in the reliability of the information that accompanies it. The commercial collection of fossils is usually driven by other pressures, and unfortunately there are far too many examples where the information valued by scientists is not collected. Or worse, where the information is unreliable or even falsified. Too frequently people looking to sell fossils for large monetary gain collected the fossils illegally, or dishonestly, and then seek to hide those facts from buyers. The temptation of large payoffs is often too great.

From a scientific stand point the value of a fossil is significantly reduced if we do not know, or cannot rely on, certain basic information. Where did the fossil come from? Who collected it? Can we be sure it is one fossil or is it a composite of two or more fossils? Could it be a forgery? Do we have records of the fossil’s context with the surrounding rocks? What did the rocks tell us about the environment in which it was buried? What other fossils were found with it that would give clues to the environment in which it lived? What clues were with the fossil that may have gotten removed during the preparation of the fossil?

The primary “currency” of academic paleontologists is integrity—if our colleagues lose trust in our work and our word we have nothing. So, there is little incentive to deceive or falsify our data or claims, and in fact there is a great potential for career-ending consequences if one is caught being dishonest.

Unfortunately that is not the case for commercial collectors. In a climate where you can sell a fossil for millions of dollars you just need to do that once to be set for life. The integrity and motivations of commercial collectors is then suspect; there are just too many examples of theft, lies, and deceit.

I am not implying anything about the people involved in the Dueling Dinosaurs. Rather, I am saying that the general lack of academic enthusiasm for their fossils is because of past experience. The prices demanded are out of reach of museums and the risk of obtaining false data is just too great. When the next biggest, best, and rarest fossil comes around we must watch their sale with detached sadness, and hope for the best.

Perhaps the Dueling Dinosaurs will end up at a museum, and maybe any questions about the integrity of those fossils can be satisfactorily addressed. Perhaps those fossils will become a conversation piece in someone’s trophy room, and if so they will likely be lost forever to science and by extension to all of us.

Fortunately, the public lands of the United States are available to researchers, where the ownership of fossils is clearly established to be the public, and commercial value plays no role. There, and on private land generously made available by land owners, scientists and genuine amateur enthusiasts can collect, study, and learn about the past with fossils that can advance our knowledge.

For the landowners, field collectors, and the people involved in buying and selling fossils I guess I have to say I don’t blame you for your interest. Fossils are cool. And if you make a million dollars, I guess good for you. However, understand that the commercial collection and sale of fossils has virtually nothing to do with the science of paleontology. The only commonality between the two is the fossils, and whereas commercial fossils may have a high market value, their scientific value is severely compromised.

The largest pterosaurs have not been grounded yet

In one post (New evidence on the size of pterosaurs) we explored the study by Henderson (2010) in which he modeled pterosaur body forms to generate estimates of body mass. He modeled different areas of the body separately, applying various densities to the different body sections to calculate his masses. His results suggested that the largest pterosaurs like Pteranodon (wing span of 17.5 feet) and Anhanguera (wingspan 13.5 feet) weighed about as much as the heaviest flying birds (41 and 14 pounds respectively). He reasoned that birds represent a reasonable analogy for flying limits in vertebrates, so this range of masses could represent the upper limit of being able to have powered flight in vertebrates.

His results for the giant pterosaur Quetzalcoatlus were astonishing. His calculations suggest that this animal weighed in at 1200 pounds, with a wingspan of almost 37 feet. After discussing various ways to interpret this result, Henderson suggested that maybe these truly giant animals did not fly at all, but were secondarily terrestrial. This evolutionary track can be found among the birds with giants like ostriches and emus growing large and losing the ability to fly.

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

Henderson’s work and conclusions was challenged by Witton and Habib (2010). Their criticisms involve several arguments. First, they suggest that birds may not be the best models for flight capacity, and that wing structure, overall anatomy, and launch mechanics were very different in pterosaurs. If so, then using birds as models for flight requirements and limitations in pterosaurs could significantly skew the results.

The heart of the arguments of Witton and Habib are the estimates of wingspan and mass suggested previously for pterosaurs. They note that relatively modest difference in wingspan calculations could have dramatic implications for calculations of mass. They state that mass estimates for a pterosaur with a 43 foot wingspan would be almost twice the estimate for a pterosaur with a 33 foot wingspan. Their assessment of the fossil material suggests that no pterosaurs had a wingspan of greater than 33-36 feet.

Likewise, Witton and Habib are critical of the body shape models used by Henderson for Quetzalcoatlus, arguing that his estimates of body size were too large, and were responsible for the very high mass values he obtained. Combined with Witton and Habib’s wingspan estimates, they calculate a body mass for Quetzalcoatlus of about 440 pounds, about one third the value of Henderson.

All of this discussion about wingspans and weights teases us with the question we really want to know—did the largest winged animals ever known actually fly? Could we have looked up into the Mesozoic skies and seen an animal flying overhead with a 34 foot wingspan and weighing as much as a tiger?

The problem, as is often the case in paleontology, is a lack of fossil material. The preserved material of these large pterosaurs is very fragmentary, and this significantly impacts our ability to accurately estimate their overall size and mass. We have in these two studies outlined here two extremes. We need more fossils before we can really know which study is most accurate.

Also, it is likely that birds may not be the best models for pterosaur flight as pointed out by Witton and Habib. Birds do things very differently than bats, our only other modern flying vertebrate, and it is most likely that pterosaurs had unexpected adaptations. For example, Habib (2008) is finding evidence for a vaulting launch in the largest pterosaurs.

Check out this video on the Quadrupedal launch in pterosaurs for an interesting viewpoint.

The largest pterosaurs have not been grounded quite yet.

References:

Habib, M.B., 2008. Comparative evidence for quadrupedal launch in pterosaurs. Zitteliana, B28: 159-166.

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

Witton, M.P. and Habib, M.B., 2010. On the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues and comments on pterosaur flightlessness. PloS One, 5(11): 1-18.

What to call the giant cat from the Ice Age?

The Ice Age of the recent past was a fascinating time, full of superlative animals, especially the mammalian megafauna of North America. The Ice Age, also referred to as the Pleistocene epoch, lasted from 1.9 million years ago to 10,000 years ago, and was characterized by a series of glacial advances and retreats across much of the Northern Hemisphere. It was also a time of animal migrations between continents and of many species being exceptionally large.

Giant ground sloths, the giant short faced bear, saber-toothed cats, mammoths, and mastodons all tromped through what was to later become our backyards. Many people are surprised to learn that North America was also home to a very large cat, larger than the modern lion, given the scientific name Panthera atrox.

This big cat lived mostly across the western half of North America, and ranged into South America as far as Peru. Its remains are plentiful in the tar pits of Rancho La Brea. It is clear that this is a big animal. Estimates of body size suggest a weight of about 1,000 pounds, and that it stood 4 feet at the shoulder. For comparison, the modern African lion weighs in at about 375 pounds. This American cat would have been the second largest mammalian predator, right behind the giant short faced bear. (See How big was the Giant Short-faced bear?)

The giant American cat, Panthera atrox

However, understanding how this animal relates to other large cats has been difficult. Scientists have noticed similarities between P. atrox and the modern lion, tiger, and jaguar. For many years, P. atrox was thought to be a subspecies of the lion, and so it has popularly been called the American Lion, and even the American Cave Lion. If it is closely related to the African lion, it suggests that lions migrated out of Asia and into the New World during the Ice Age, expanding as far south as South America, and becoming extinct at the end of the age. Several other species are known to have done this, so that is not so unusual. But is it an accurate story?

In a recent paper on the subject (Christiansen and Harris 2009), researchers have come up with a different idea. They examined the skull and jaws of the big American cat and compared it with lions, tigers, and jaguars. They used a wide range of measurements to create a mathematical model of each species, and compared them to each other. The result? Panthera atrox does not seem to be a lion at all, but rather is closest to the modern jaguar.

Jaguars came into the New World from Asia during the early Pleistocene. It seems then that P. atrox and the modern jaguar species, P. onca, are derived from the early jaguar that came into North America, and that lions never made that long trek across. If these researchers are correct, we should not call this magnificent cat the American Lion.

A jaguar, Panthera onca. By Pascal Blachier from Savoie, France.

So, what should we call it? Jaguars are native to the New World, so the word “American” seems a bit redundant in the name. And the simple scale and grandeur of the cat requires some adjective. “Mega Jaguar” seems a bit plain to me. What do you suggest?

Christiansen, P. and Harris, J. M. 2009. Craniomandibular morphology and phylogenetic affinities of Panthera atrox: implications for the evolution and paleobiology of the lion lineage. Journal of Vertebrate Paleontology 29(3):934-945.

Mammoth protein designed to be cool

Researchers were recently able to isolate and study woolly mammoth hemoglobin and compare it to the modern African and Asian elephants. They isolated the genes from DNA that code for the creation of hemoglobin, the protein that carries oxygen in our blood. This was done for both the modern elephant species, as well as from DNA from mammoth bone from Siberia. They observed some minor differences between all the species, so the researchers wondered if the difference in the mammoth’s blood might have helped it survive in cold climates.

Hemoglobin supplies our body with oxygen by carrying it around in our blood stream and then releasing it to our tissues. When our tissues need more oxygen, like for muscles that are working hard, hemoglobin more easily releases oxygen because of the higher temperatures created by the heat generated by the muscle. However, in colder temperatures, hemoglobin does not give up oxygen as easily. This is potentially a real problem in colder climates. To keep the hemoglobin to working effectively an animal might need to expend valuable energy to maintain a higher body temperature.

The researchers (Campbell et al. 2010) wondered if the slight differences in woolly mammoth hemoglobin might have been an adaptation for living in colder temperatures. They inserted the Asian elephant genes that make hemoglobin into the common bacteria, Escherichia coli, and allowed the bacteria to act on the genes, thereby making Asian elephant hemoglobin. This process is not new as it is commonly used to have bacteria produce proteins that are identical to human-made proteins, like insulin.

To get the bacteria to make mammoth hemoglobin, they needed to modify the Asian elephant genes the same way they observed, then let the bacteria make the hemoglobin of a mammoth—thousands of years after the mammoths last did it themselves. Researchers could then compare the protein of the two species directly. The result was that mammoth hemoglobin released oxygen much more effectively at lower temperatures.

Woolly mammoths from Alan Turner (2004), National Geographic Prehistoric Mammals.

Woolly mammoths were adapted to colder climates in a number of ways, such as compact bodies, small ears, short tails, and long woolly hair. This result strongly suggests that their bodies were also changed at the molecular level for life in cold, high latitude climates during the Ice Age. It would be very interesting to see if other mammoth species, such as the Columbian mammoth, for example, shared this adaptation. But I suppose that will have to wait until we can get good DNA from that species. All in good time.

Campbell, K. L. et al. 2010. Substitutions in woolly mammoth hemoglobin confer biochemical properties adaptive for cold tolerance. Nature Genetics 42:536-540.

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 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" 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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