An Interview with Karen Chin
Author: Beverly EschbergerPublished on: Mar 10, 2000
Dr. Karen Chin began studying coprolites while she worked with paleontologist Jack Horner at the Museum of the Rockies in Bozeman, Montana. She received her doctorate in geology from the University of California at Santa Barbara and is now a visiting scientist at the U. S. Geological Survey. I first met Karen in Montana, where she was looking for some more coprolite specimens. Until I talked to her about coprolites, I had never thought about the scientific value of fossilized dung, but Karen has made me see how important they are.
"Karen, how did you first become interested in studying dung?"
"I used to work as a park naturalist for the National Park Service, and I led a lot of nature hikes. You are more likely to see animal sign than actual wildlife when you are looking for them, so I got used to looking for trails, marks on trees and scat. Dung can tell you a lot about an animal or group of animals. It can tell you about their diet, how healthy they are and how many animals are in a herd."
"What do people usually say when they find out what your area of study is?"
"They tend to be really surprised. Surprised that feces actually fossilize, and that people take the time to look at it. But then they usually become fascinated by it."
"Why would you want to work on fossilized dung instead of something more interesting, like bones?"
"Well," she laughs, "interesting is a relative term. Bones do tend to be more straightforward, but coprolites give us glimpses of ancient ecosystems. I think studying coprolites complements the study of bones. Coprolites can tell us about the interactions between vertebrates and other animals. We can learn about dinosaur and plant interactions and dinosaur and dung beetle interactions.
"It is a difficult area of research. It can be difficult to deduce if what you are looking at is fecal material and difficult to determine who produced it. It is not a straight-forward area of research and certainly not well-studied. But I find it is an exciting frontier of paleontology to be working in."
"Is it difficult to recognize coprolites in the field?"
"Yes, it can be. Smaller coprolites often hold their shape well: with the exception that they are turned into rock and are a different colour, they look just like dog feces. But coprolites from larger animals can be distorted and do not always look like dung. You have to look at their contents to really tell. You have to look for chopped-up plants and animal parts."
"One of your research projects involved a coprolite mass from southwestern Saskatchewan attributed to a species of tyrannosaur. What clues helped you to determine that it was from a tyrannosaur?"
"First, we looked at the contents of the coprolite and found chopped-up bone. Also, it was highly phosphatic, telling us that it was definitely a coprolite. Both of these things told us that a carnivore had left this coprolite. Then, I calculated its density by submerging it in water and calculating its displacement. I calculated a volume of about 2.4 liters, which is a sizeable amount of fecal material. Then, we examined a list of carnivores known to have lived in the Frenchman Formation [the stratigraphic formation the coprolite was found in]. Most of the carnivores weighed less than 100 kg, with the exception of T. rex, who has an estimated body weight of 5,400 to 6,300 kg. So, unless there is another large carnivore that is not represented in the fossil record, we are pretty sure that this coprolite came from a tyrannosaur."
"Is there anything else you would like to tell our budding young paleontologists?"
"Pay attention to all clues from the fossil record. Bones may be the most important, what is looked at most often, but there are smaller, less conspicuous animals to examine. Also, the flora and micro-organisms all work together with vertebrates in the ecosystem. It is worthwhile looking at even lowly fecal matter!"
More about the T. rex coprolite
If you are interested in learning more about coprolites, Dr. Karen Chin recommends the following sources:
"A king-sized theropod coprolite" by Karen Chin, Timothy T. Tokaryk, Gregory M. Erickson, and Lewis C. Calk, Nature vol 393 pages 680-683 June 18, 1998
"Dinosaurs, dung beetles, and conifers: Participants in a Cretaceous food web" by Karen Chin and Bruce D. Gill, Palaios vol 11, pages 280-285 1996
"The paleobiology of vertebrate coprolites" by Adrian Hunt, Karen Chin, and Martin G. Lockley, pages 221-240 in The Paleobiology of Trace Fossils edited by S. K. Donovan, John Wiley and Sons, 1994