Skepticblog

I am a vertebrate paleontologist. I have collected fossil bones out in the Big Badlands of South Dakota and many other places all over the western United States. Although I have collected plenty of dinosaur fossils, I don’t do research on them, but on fossil mammals that are equally cool, including North American rhinoceroses, horses, camels, musk deer, peccaries, and a number of extinct groups that only another mammalian paleontologist would recognize, such as oreodonts and dromomerycids.

People seem to think that my primary job is to collect new fossils and describe them, but in most cases, this is not true. I could spend dozens of man-years getting sunburned in the desert, and not find but a few really scientifically important specimens. Luckily for me and many other paleontologists, there have been many collectors over the past century who have done the hard work in the field, building up large collections in the major museums. What has been missing for a long time is people who want to spend the months and years figuring out what these new fossils are, describing and publishing them, and giving us a correct and up-to-date picture of what fossil animals lived when and where. This is called systematics, and although it’s not as glamorous as the “Indiana Jones”-“Jurassic Park” image of paleontology that most people think of, it is the most important job in paleontology. Without hundreds of hours of careful work in museums, measuring and studying and photographing and then publishing the fossils in highly specialized  monographs that only a few people can understand, all the computer-driven arm-waving about how many species lived at a given time, or what caused their extinction (all based on outdated names or incorrect identifications) is “garbage in, garbage out.”

Most of the time, this work goes on quietly in musty museum basements in the research collections that the public never sees. In the American Museum of Natural History in New York City (where I earned all my graduate degrees from 1976–1982), there are SEVEN FLOORS of fossil mammals in storage, much of which has never been fully studied or published. There’s a whole floor of mastodonts and mammoths, a whole floor of horses, a whole floor of camels, a whole floor of rhinos, and three floors of all the other fossil mammals. Literally, everything that was thought about North American mammals from 35 million years ago to the Ice Ages has to be redone or rethought as all these new unstudied specimens are published. I spent almost 25 years of my life documenting the history of American rhinoceroses (published in Prothero, 2005). For the past four years, I’ve been in the midst of documenting the history of the peccaries or javelinas (pig-like American mammals only distantly related to true pigs).  I hope to finish working out the history of North American camels before I die.  Large systematic monographs like my 2005 rhino volume don’t sell a lot of copies, but they are the foundation of everything we do, and every paleontologist who wants to identify a rhino specimen must now start with my  book. The content of books like this often last for generations, since we always have to go back and look at earlier people’s work to figure out what we think now. In the case of rhinos, there was so much new material to work with (and it’s unlikely that anyone will accumulate that much new material again) that my rhino book will still be used over a century from now, just like I consult old works from 1895 or 1900 when I start a project. Very few works in science have that kind of relevance or longevity, even if only a handful of specialists know about them.

A paleontologist/systematist has to be a skeptic and a detective, looking for all sorts of clues to sort out what fossils belong together, which fossil species are valid, and what is the correct name for the fossils that are often misnamed. Sometimes we find great unsolved mysteries that puzzle us and cannot be resolved. In other cases, we often have amazing luck. Take, for example,  a strange lower jaw of a 60-million-year-old animal from Mongolia that William D. Matthew and Walter Granger had named Phenacolophus in 1925. They had no idea what this scrappy jaw was, and no new material had been found since then. But 40 years later, my former graduate advisor Malcolm C. McKenna happened to be visiting a museum in Moscow when he saw another jaw fragment that looked very similar to the mystery jaw in New York. The next time he returned to Moscow, he brought a cast of the American Museum specimen of Phenacolophus with him. Amazingly, they fit together! It turned out that the back half of the jaw had been collected by American Museum scientists in 1923, and in 1948 Soviet scientists had found the front half of the same jaw in the same locality! Only a scientist with a good eye for fossils and a good knowledge of the collections (like McKenna had) could have recognized how these two pieces of the puzzle fit. With a nearly complete jaw, McKenna and Manning (1977) were able to show that Phenacolophus was a very early relative of  the lineage that today includes elephants and manatees (see Prothero and Schoch, 2002, pp. 142–143).

I’ve had similar moments in sorting out which rhinoceros species are valid, and which names are invalid and should be discarded. In my 2005 rhino book, I got rid of almost 100 invalid names that were still in the literature and never formally invalidated—and described several new species and genera based on the brand new materials in the collections. It’s always fund to name a new species, and the new rhinos I described were mostly named after scientists who found the fossils or figured them out. However, as the namer of a new fossil, I can give a species almost any name (as long as it follows the rules). One of the new rhinos I named after my wife’s family as an anniversary gift to them. The only thing you can’t do is name a new species after yourself. But you can name it after someone else, and that person can then name their next new species after you. In 2008, my colleague Spencer Lucas named a new fossil rhino Zaisanamynodon protheroi after me, so one of the new peccaries I’m working on will be named in his honor.

When I worked on the early American camels in 1982, I found a particularly remarkable case of the complex confusion regarding names. I had in front of me a puzzling broken lower jaw described by Matthew in 1901 as Protomeryx cedrensis. It had a distinctively short premolar tooth row not seen in other camels.  In the same drawers were casts of other camels, including the fragmentary upper jaws of a camel from the Yale collection described by Richard Swann Lull in 1921 as Pseudolabis (Paralabis) matthewi. It too had extremely reduced premolars, but Lull had never compared it to Matthew’s specimens, but only to camels like Poebrotherium and Pseudolabis that were completely different from this specimen. I also had on loan a good lower jaw from the South Dakota School of Mines collections that came from the same late Oligocene beds in the Big Badlands as Lull’s Yale specimen. When I fit the upper and lower teeth together, they were a perfect match! (see Prothero, 1996, fig. 9). They had probably been collected from the same area, but by different institutions many years apart, and no one realized they were the same thing. The South Dakota lower jaw was also a good match for the more broken lower jaw that Matthew had described almost a 80 years before.

So what name was the proper one for these specimens that were clearly the same genus and species? Matthew’s use of the name Protomeryx was no good, since the original specimen of that genus was so poorly preserved that you can’t tell what it was, and it has long been abandoned. Nor was this species referable to Pseudolabis, a genus that now looks very different based on the more complete material in the new American Museum collections. It turned out that Lull’s 1921 subgenus Paralabis is the first available name to describe the taxon, and that is indeed its current genus (elevated from its original subgenus rank).

But what species name is proper? Here the problem got even more complicated, and the scientists who have mentioned this camel since 1901 got very confused. In Matthew’s 1901 monograph, he mistakenly used two different names for the same specimen: Protomeryx cedrensis in some places, and Protomeryx campester in one other place (this is known as a lapsus calami, or “slip of the pen”). Some later authors thought that this meant there were two different species, but it was clear it all refers to the same specimen, and that Matthew was careless in  his original description. In a 1904 paper, Matthew used the name campester again, but in all his later publications he used the name cedrensis, including in a manuscript that was unpublished at the time of his death. Since the name cedrensis appeared on p. 358 and the name campester appeared on p. 422, the criterion of page priority and the author’s intent as first reviser are clear. According to the International Code of Zoological Nomenclature, the correct name for this camel is Paralabis cedrensis. It’s a good thing that this worked out, because there is a closely related camel named Oxydactylus campestris, which could easily be confused with the valid species of Paralabis. If some later paleontologist (including me, possibly) should decide that Oxydactylus and Paralabis are the same genus, then there would be two different species with the name campester or campestris. In zoology, it is not permissible for two different species in the same genus to have the same species name (this is known as secondary homonymy).

This may seem like a lot of boring bookkeeping to some people, but it is actually very interesting and challenging work: studying and measuring and sorting out hundreds of specimens, deciding which previously named species are valid, and then using every possible skill as a detective to figure out which name is the proper one, and getting rid of names that are no longer valid based on better new material (or due to the incompetence of earlier paleontologists or their outdated ideas). All this unglamorous detective work establishes the foundation for paleontologists and zoologists to tell us how many species really lived in a given time or place, which is essential to studies that look at diversity changes through time, and how they relate to modern biodiversity. Most systematists may not use expensive high-powered machinery (other than a laptop with a spreadsheet and some digital calipers), but without our work all of paleontology and biology would grind to a halt.

A CODA: As I was preparing this blog, I did a search of the name “Paralabis” to see what was online (completely impossible when I first did this research in 1982, or published it in 1996). Lo and behold, that name had already been used for an earwig by Burr in 1915. By the rules of priority, it cannot also be used for a fossil camel named by Lull in 1921. Darn! Oh, well, there’s a bright side: it’s time to publish a short paper pointing this out, and giving the camel a new generic name (hopefully something that hasn’t already been used by another earwig!). Any suggestions?