Wednesday, October 14, 2015

The First Trilobite

NOTE: In honor of National Fossil Day here's a post I wrote five years ago about a famous trilobite.

In their early days, scientific journals were much more generous than they are today about publishing letters from experimenters and collectors in all walks of life. The hard wall between scientists and amateurs had not yet been built and all literate people were, in theory, entitled to participate in the discussion. One such person was Rev. Edward Lhwyd (or Lhuyd or Lhwid or Lloyd), the illegitimate son of a member of the minor gentry who rose from genteel poverty to become keeper of collections at the Ashmolean Museum in Oxford (an unpaid position, but important in the community of science). The 1698 volume of The Philosophical Transactions of the Royal Society, the oldest scientific journal in the English language, contains "Part of a Letter from Mr. Edw. Lhwyd to Dr. Martin Lister, Fell. of the Coll. of Phys. and R. S. Concerning Several Regularly Figured Stones Lately Found by Him." The two-page letter is accompanied by a page of etchings of the figured stones or, as we would call them, fossils.

Lhwyd collected his fossils during a trip to Southwestern Wales. Number fifteen, in his etchings, he found near Llandeilo, probably on the grounds of Lord Dynefor's castle. He wrote of it: "The 15th whereof we found great Plenty, must doubtless be referred to the Sceleton of some flat Fish..." A century and a half after he wrote that, Sir Roderick Murchison would place the Llandeilo rocks in the middle strata of his Ordovician Period. A century after Murchison, scientists would date that strata between 461-63 million years old. That is less than ten million years after the first plants took root on dry land and a hundred million years before cockroaches crawled out of the sea looking for a snack.

Lhwyd's "flatfish." Today we call it Ogygiocarella debuchii (Brongniart).

Lhwyd's identification of number fifteen as a flatfish didn't last very long. Today anyone with even a casual knowledge of fossils will recognise it as a trilobite, something more like a shrimp than a halibut. Lhwyd didn't have our advantage of hundreds of years of fossil studies producing thousands of lavishly illustrated and easily accessible books. It would be almost a century before the word "trilobite" would be coined and into Murchison's time before the scientific world would realize that trilobites were not related to halibut or shrimp (or oysters, another contender) but, rather, something entirely their own. Lhwyd was plunging ahead in the dark trying to make sense of an unfamiliar and mysterious corner of nature.

Lhwyd deserves great credit for deciding his little flatfish was worthy of notice and for sending his drawings to the Royal Society, although, sometimes, he gets a little too much credit. His illustration is the first published scientific illustration of a trilobite that we know of, but he did not "discover" trilobites, as some books will tell you. We should always regard any claim that someone discovered a fossil species with suspicion. Trilobites are extremely common fossils and can be found laying on the surface in many parts of the world. Our ancestors were both aware of fossils and, in many cases, aware that they were the petrified remains of once living things. Usually, what an author means when they declare that this person or that person discovered a fossil is that they were the first to describe the fossil in scientific literature. Lhwyd's illustration certainly counts as a description in that sense, but it is not the first description we know of.

No one can say when people first noticed that fossils were different than other rocks except to say that it was very long ago. The first step in making stone tools is to examine stones very carefully, so it is possible that our ancestors were aware of organic patterns in rocks over a million years ago. For trilobites, specifically, the earliest evidence of humans treating a fossil as something specially comes from a cave near Yonne, France. In the 1880s, when archaeologists were combing the caves of central France looking for artifacts, bones, and paintings, they discovered a much handled trilobite fossil that had been drilled as if to be worn as a pendant. The cave where it was found is now known as Grotte du Trilobite and is also home to paintings of mammoths and woolly rhinoceroses. Because the pendant was handled so much, the exact species of trilobite cannot be determined, however, geologists can say that it was not originally from Yonne. The original owners of the fossil thought enough of it that they carried or traded it from the other side of France. The occupation strata in which the trilobite was found has been dated as fifteen thousand years old.

The oldest known human trilobite artifact from the Grotte du Trilobite.

In the New World, American fossil hunters found plentiful deposits of trilobites in western Utah in the 1860s, but the local Ute Indians had known about them for untold years. In 1931, Frank Beckwith uncovered evidence of the Ute use of trilobites. Travelling through the badlands, he photographed two petroglyphs that most likely represent trilobites. On the same trip he examined a burial, of unknown age, with a drilled trilobite fossil laying in the chest cavity of the interred. He asked Joe Pichyavit, a Ute friend, what the elders said about such fossils. Pickyavit replied that trilobite necklaces were worn as protection against disease and bullets. The local Ute name for trilobite fossils translated roughly as "little water bug in stone," indicating that they recognised the organic nature of fossils. Pickyavit then made a necklace for Beckwith in the old style. Since then, trilobite amulets have been found all over the Great Basin, as well as in British Columbia and Australia.

Probable trilobite petroglyph. Beckwith's label reads "A shield (?) shaped like a trilobite."

Joe Pickyavit's trilobite protective necklace made of fossils, clay beads, and horsehair tassels.

Written descriptions of trilobites before Lhywd date possibly from the third century BC and definitely from the fourth century AD. Most ancient literatures include a genre called lapidaries, catalogs of precious stones and minerals along with their practical uses in medicine and magic (often the same thing). Most of the lapidaries included discussions of fossils and one, On Petrifactions by Theophrastus, was entirely about fossils. Sadly, the book has not survived and we know only short quotes from it in the works of later authors. The Spanish geologists Eladio Liñán and Rodolfo Gozalo argue that some of the fossils described in Greek and Latin lapidaries as scorpion stone, beetle stone, and ant stone refer to trilobite fossils. Less ambiguous references to trilobite fossils can be found in Chinese sources. Fossils from the Kushan formation of northeastern China were prized as inkstones and decorative pieces. A dictionary commentary written around 300AD by Guo Pu, refers to these fossils as bat stones because the spines on the pygidium (rear section) resemble the bones of a bat wing. The Khai-Pao Pharmacopoeia, written in 970 refers to the fossils as stone silkworms. Just nine years before Lhywd sent his letter to the Royal Society, Wang Shizhen wrote about the Kushan formation fossils a narrative of his travels in North China.

None of this should diminish Lhywd's place in the history of paleontology. Lhywd's observations were made within the framework of the emerging Western concept of science. The fossils were not interesting oddities that he found in the course of doing something else; they were the object of his outing. Lhywd took an artist along with him on his trip to Wales for the express purpose of preparing scientific illustrations. He communicated his observations to other scientifically interested people with the understanding that they would get further distribution. Finally, Lhywd gathered his fossils and took them back with him to the Ashmolean Museum where others would be able to study them.

As for number fifteen, it's not clear whether the fossil trilobite itself has survived. Modern curators at the Ashmolean have tried to identify Lhwyd's fossils in their collections. They have one old trilobite that approximately matches number fifteen, but they are unable to make a positive identification. The Romantic in me hopes its the one.

Number fifteen?

Saturday, October 3, 2015

Mammoth in the News: Michigan Edition

You might have seen in the news yesterday that a mammoth was found in Michigan. A new mammoth find is always cool and this one has a few elements that make it pretty exciting. I have some questions about it and there is one aspect of the story and accompanying pictures that I find fairly disturbing.

NOTE: Though the story has been picked up by most major news outlets, the source for most of the coverage is these two stories from MLive, a group of regional newspapers in Michigan (one, two). The Washington Post story was able to add a little by interviewing Dan Fisher, the paleontologist directing the excavation (link).

First, the story. On Monday, James Bristle and a friend were digging a hole in a new piece of land Bristle had just acquired. The hole was to be the base of a lift station for a new natural gas line being built. A few feet down, they brought up something long, narrow, and curved. At first they thought it was an old bent fence post, but once they had cleared some mud off of it, they saw that it was a huge rib. Bristle brought his family to look the rib and other bones he uncovered. On Tuesday, he called the University and was put in contact with their paleontology professor, Dan Fisher. Fisher came out Wednesday night and by the morning he was sure they had woolly mammoth on their hands. His initial theory is that the mammoth was butchered, and possibly killed by humans, and that the parts they discovered had been sunk in a cold pond for storage.

Here's the exciting part. Mammoths are not common in Michigan. Mastodons are. The state fossil of the Michigan is the mastodon. Fisher says this is only the eleventh significant mammoth find in the state while there have been over 300 mastodon finds. “We get calls once or twice a year about new specimens like this,” but they're always mastodons. If he's right that it was butchered by humans, that's even more exciting. Very few mammoths have ever been found that unambiguously show evidence that humans killed or butchered them.

Here are my questions. Based on what I can gather from the news reports, Fisher's theory seems reasonable, but, of course, I want to know more. What makes him think it was butchered? The reports say they found a flint cutting tool at the site. It's possible that the tool was left there at another time, but, if it was found intermingled with the bones, it's far more likely that it was deposited at the same time as the mammoth. The clincher will be if they find butcher marks on the bones--that is, gouges on the bones made by sawing meat off. I'd also like to know more about the pond refrigeration theory. This technique was practiced in the region and can keep meat safe to eat for over a year, though it tastes and smells awful by the first summer. I want to know if there's any way to confirm that this is really what was done with this particular mammoth. Third, Fischer thinks the mammoth was about forty when it died. He most likely figured this out by counting the growth rings in the ivory (mammoths and elephants show annual layers just like trees). One of the tusks was broken about half way up during the recovery, making that technique possible on the site. Adult elephants grow a new set of teeth every ten years or so. Did he deduce it from that? I want to know more about everything.

Now the disturbing part. After Dr. Fisher determined that the bones were mammoth remains, farmer Bristle gave him the rest of the day to get the bones out of his field before he planned to go back to building his lift station. This makes no sense to me. I understand that there are people who care so little about science that one day's inconvenience is all they're willing tolerate for knowledge. But that still doesn't explain the rush. Why is he building the lift station? Shouldn't the pipeline company be doing that? Shouldn't they be setting the schedule? Because they were found on private property, the bones are legally Bristle's. At press time, he hadn't decided whether he was going to donate the bones to the university after they finished examining them, so he has some interest in them. Even if his interest is only in selling them, he has to know that a careful excavation will bring the bones out in the best possible condition guaranteeing the best possible sales price. An important part of the story is missing here.

Fisher was able to call in a bunch of his students to help him. Jamie Bollinger, a local excavator, donated his time and equipment to get the work done. The The Ann Arbor News interviewed Fisher while the skull was being prepared to be lifted out of the hole by Bollinger's backhoe. Other than clearing the mud away, the only preparation they were able to do under the time restraints they faced was to wrap the tusks with zip ties. One broke anyway.

I'm cringing at the pictures, but maybe it's not as bad as it looks. They got the bones. That's all that's important. Right? Well, no. We know what mammoth skeletons look like. Over the last three hundred years, we've found bones from thousands of mammoths including a good sized herd's worth of complete skeletons, not to mention 75 with meat or skin. The important thing now is to study the context of each discovery. What was the local environment this mammoth lived in? What was the climate? What were they eating? Were humans part of that environment? Fortunately, evacuation paleontology/archaeology is a technique with well-developed procedures. In the pictures you can see that students have bagged scores of samples and carefully labeled each one. It might take years to examine the samples and virtually reconstruct the site. With computers, we can do that a lot better than we used to.

I'm really looking forward to hearing what they can tell us after they've had a chance to carefully examine the bones.