A portrait of Karen Chin

by Steve Brusatte

Jack Horner is an expert on the social structure of dinosaurs. John Ostrom is considered highly knowledgeable on the issue of dinosaur-bird evolution. Walter Alvarez is known as a pioneer of dinosaur extinction studies. And, Karen Chin is considered the world\'s expert on the subject of dinosaur poop!

Dinosaur poop? Yes, that is right, Dr. Karen Chin of the United States Geological Survey is considered the world\'s foremost expert on dinosaur coprolites, or fossilized dung. In this highly unattractive field Karen Chin is a star, or shall I say, growing star?

Despite the fact she is barely out of college, Karen Chin is already a worldtraveling lecturer, not to mention highlytouted author. But, her beginnings were much humbler. As a young girl Karen wasn\'t very interested in paleontology, but instead loved general science, trees, flowers, birds, and reptiles. \"I didn\'t like dead things,\" she jokes. Then, in college she took a geology class and was hooked. Later on, while working on her Master\'s degree at Montana State University, she met Jack Horner and got the chance to work with him at the Museum of the Rockies. This honor motivated her further.

Dr. Chin first remembers becoming interested in coprolites during the time she worked for Horner in Montana. In addition to taking pictures for him and designing exhibits, Chin also got to dig and write. One of her papers concerned a coprolite. As with paleontology a few years earlier, she once again became hooked, but this time with coprolites. She then went off to the University of California at Santa Barbara and received her Ph.D in 1996. Today Dr. Chin remains at her original post doctoral position-as a visiting scientist for the United States Geological Survey in Menlo Park, California. Her research, including of course-dinosaur dung-is fully funded by grant money.

Many dinosaur fans consider Dr. Karen Chin as one of paleontology\'s \"rising stars.\" One of the major reasons for this title is that she is basically the only major coprolite researcher in the world. After originally studying these pieces of dinosaur dung in college (in order to further understand dinosaur-plant interaction), Chin went onto pursue a career studying coprolites, and the rest is history!

\"There are more clues on a dinosaur\'s diet than once thought,\" she told the large audience during a February 1999 lecture at the Burpee Museum of Natural History in Rockford, Illinois. She went onto explain that there are four basic ways to determine the diet. First off, she stated, was to look at the anatomy of the animal, especially the teeth. Obviously, a long, sharp, pointed tooth is a surefire sign of a meat eating dinosaur. Secondly, look at the contemporaneous organisms the dinosaur in question shared an ecosystem with. In the Triassic there were many ferns and conifers, later in the Cretaceous flowering plants appeared,\" Chin explained with a slide show.

A third way to determine the diet is to look at gut contents, if they preserved in the form of a fossil. Although there are some examples of fossilized gut contents, such as the skeleton of a juvenile Coelophysis found fossilized in the stomach of an adult in New Mexico, this way of determining is much harder because of the rarity of the fossils. And, the fourth major way to determine a diet is by referring to trace fossils. As you probably know, a trace fossil is not the actual fossilized remains of an animal or organism, but the fossilized \"traces\" of an organism. Some examples are footprints, tooth marks, and of course, coprolites. This study of coprolites was the basis and topic of Chin\'s popular lecture.

After discovering a coprolite, Karen explained to us, there are four basic questions one must consider. 1) Is it fecal matter? 2) If so, who was the perpetrator (or as she put it, this is the \"species feces\" question), 3) Has material been well preserved in the fossil feces, and 4) (get this!) \"Does fecal matter?\"

As Allen Debus and I originally wrote in a Fossil News article covering Chin\'s talk, Essentially, after making some laboratory measurements and observations, once can distinguish fecal matter from material of sedimentary origin. Clues as to the probable species are gleaned from knowledge of geologic occurrences of contemporaneous species and also their relative body size.\" One major example of this inference relating to body size is 1998 paper entitled, \"A kingsized theropod coprolite.\" In this paper, praised by many dinosaur researchers, Chin and colleague Dr. Greg Erickson of Brown University claimed a 44 centimeter long piece of fossil dung, collected by Royal Saskatchewan Museum scientists Wendy Sloboda and Tim Tokaryk in 1995 in Upper Cretaceous sediments, belonged to of all dinosaurs, T. rex.

After numerous laboratory chemical tests Chin determined that the fossil was indeed a coprolite. She then went onto label it as belonging to a carnivore, for she found small pieces of bone inside. Because chemical tests could not directly point to the poop-etrator (as she called it!), Chin was forced to use the process of elimination. After intense research she came to realize that five meat eating creatures had been found in the Upper Cretaceous coprolite-bearing sediments. These animals included: the romaeosaurids, the Elimisaurids, Leidyosuchus-a crocodile-, Troodon, and the fiercest meat eater of them all-Tyrannosaurus rex.

The volume of the coprolite was a whopping 2.5 quarts, so Chin went onto reason that only a very large beast could have produced it. Dromaeosaurids, Elimisaurids, Leidyosuchus, and Troodon all weighed less than 250 pounds, so it couldn\'t be them, Chin explained. So, by process of elimination, Chin and Erickson finally put the tag on the large Tyrannosaurus rex. \"The best candidate for the producer is T. rex,\" Chin explained, \"I am 99% sure. It is either T. rex or an even larger, currently undiscovered creature.\" But, beyond the T. rex hype, the most amazing aspect of this coprolite was the chunks of bone found within. \"T. rex must have been able to break bone a bit,\" she said, \"the bone was not completely digested, but (the T. rex) must have injested bone when they bit.\"

This evidence led Chin and Erickson to conclude that the T. rex was able to chew forcefully through bone while eating. Erickson went onto explain, \"T. rex couldn\'t chew as people do because its upper and lower teeth didn\'t meet each other. But those powerful teeth might have still pulverized bone as they sheared past each other.\"

In addition to T. rex Chin has also partaken on numerous studies involving everything from herbivorous dinosaur dung to dung beetles. If you don\'t recognize Chin as the T. rex dung woman you may recall two of her other more famous studies.

In her lecture Chin recalled a time when ankylosaur expert, Dr. Jim Kirkland, handed her a specimen that did not have the \"usual\" coprolite shape or appearance. Despite its outward appearance Chin used her chemical analysis to reveal the presence of 17 seed and bacterial fossils present in the fossil, which as she confirmed, was indeed a coprolite. Her second study involved her analysis of coprolites found in the Two Medicine Formation in Montana. Discovered near Horner\'s famous Maiasaura egg sites, these coprolites revealed the presence of conifers, dung beetles, and snails.

Chin reasoned that these clues showed that dinosaurs were ecologically linked to a variety of organisms in their paleoenvironment. In addition to these analyses, Chin also determined that the diet of several dinosaurs changed with the seasons, depending on the availability of food. All of this and only three years out of school.

But, don\'t think Karen Chin is going to retire at a really early age! Currently she is in the midst of a comparative study of about 30 different coprolites. Plus, she would like to try to analyze an interesting fossil found in Alberta and study fossil wood in the near future. Despite the fact that she is barely out of school Dr. Karen Chin of the U.S. Geological Survey is considered one of the
world\'s foremost paleontologists. And, her stock is only rising. Only God knows what piece of dinosaur dung she will study next, and surely nobody knows what she will discover inside the dung!

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