What is a typical day of field work like for you?

If we're prospecting, I go out with the rest of the team, but I look for small to medium-size fossils that clue me into the fact that small things are being preserved. These would be things like fragments of turtle shell, fish scales, dinosaur teeth, crocodile teeth, small vertebrae. All these things are visible from a standing position if you're walking slowly and your eyes are tuned to the smaller-sized things on the ground.

When I see an area that is concentrating these kinds of things, I get closer to the ground, and even smaller things become visible. Usually I'm scanning back and forth over a small area, looking over the small grains seeing if any of them match my search image of a small fossil.

A lot of the time I am on my hands and knees, or stomach. Often I'll throw on a jewelers' lens to add some magnification. But even then I might not be able to see some of the mammal teeth that may be less than a millimeter in size. You can see half a millimeter with the naked eye, but there are a lot of bigger things that distract you.

If I find something good - a small crocodile or lizard jaw, or a really nice dinosaur tooth - I pack it away in a small vial rather than make a plaster jacket. On a rare occasion I wrap something in toilet paper and pack it away.

Sometimes I can't spend time looking over an entire area where small things have accumulated so I scoop up the sediment. A lot of my work won't take place until I get the sediment back to the laboratory. There I'll wash it, sift it and sort through it in the hopes of finding something I may have missed while prospecting.

Greg using his goggles to magnify the tiny teeth he searches for.

How much sediment have you collected on this expedition so far?

I have collected three tons of sediment. That's 6000 pounds.

What are the kinds of things you could learn if you found a mammal tooth?

On one level, I might be able to say something about diet. Mammals have more complicated teeth than fish or crocodiles do. They have an arrangement of points on their teeth - like our molars - and often this arrangement has evolved to deal with different types of food. Something more herbivorous might have lower cusps and more grinding surface, and something that eats insects might have sharper, taller points to puncture through the exoskeleton of a beetle.

On another level, understanding where mammals lived can give us clues to when and where the mammals we see today originated.

How is your search going so far?

Finding a fossil mammal from Africa is a great challenge. There are just a handful of fossils known from the entire continent - from Tanzania, Morocco, and from Cameroon. People have found teeth and a piece of jaw but skull material is extremely rare.

They're very small, they're rare, and sometimes you have to collect thousands of pounds of sediment and sort through it before you find even one mammal tooth. I may find three mammal teeth or one - but because it's so difficult it would be worth the effort.

I haven't found any mammal teeth yet. Initially I thought it would be easier. I definitely thought I would have found mammal fossils by now, so the disappointment of not finding anything and spending this much time looking for mammals, has at times weighed on me But I continually remind myself that its extremely difficult to find mammals in the Early Cretaceous any where.

What might it mean if you don't find any mammal teeth during the expedition?

It could mean that the particular environment we're prospecting, this river system, or this flood plain, is not where the mammals in Niger lived during this time period. They may have had a lifestyle or behavior that put them in an area that wasn't good for fossil preservation - like the highlands. Or it could mean that they didn't exist here.

But I don't think they didn't exist here - there's no good reason why they wouldn't. They exist in a lot of other places in the world at this time - including North America and even on Africa in Morocco. But early mammal teeth are rare and hard to find.

This is the reason we don't' know a lot - it takes a tremendous effort for each tooth.

What does the rest of the team think about your work?

[Laughs] People try to give me a hard time. They call me the "thief of the Sahara" because I carry so much sand. They joke that it's not as tough as being a dinosaur paleontologist.

I think most people kid about it but they respect the potential significance of the findings here and they're always interested in hearing how things are going. Also, I do a lot of work in the pit, too, so we're all working together quite a bit.

Greg edits an e-mailed manuscript at lunch
in the makeshift Land Rover office.

What are some of the skills or qualities you've found to be important in your work?

I think it takes more than just being a scientist.

In terms of early habit forming years, my parents - particularly through academic and athletics - worked hard to instill persistence and diligence in the face of challenges. I think fieldwork is one of the times when those characteristics are important. These are difficult things we are doing in a pretty harsh environment. When you are doing a PhD those qualities are extremely important, too.

I think first year of grad school is the most difficult. I was very overwhelmed and contemplated trying something else. My brother Jeff's first year was really difficult for him, too. I remember getting letters from him and it was clear he was really struggling with everything. Personally I think it was consistent with what happened with me - and for a lot of grad students.

With paleontology students it's especially true because as an undergraduate you study biology or geology, and you often haven't been fortunate enough to have been exposed to paleontology. Then, all of a sudden you end up in a place where people specialize in it.

Over the course of the last two years I've really started to define my interests and translate them into research projects. There are a ton of things I still don't know but now I have a better idea of what questions to ask, whereas before it was a big sea of things I didn't know.

What kinds of research questions are you interested in?

I'd like to continue working on Mesozoic mammals. There are a lot of people who have done great things recently on southern continents, but there's a lot still to be learned from places like South American, India - remote locations, areas more difficult to work, where people haven't put in time or effort.

I think my interests are in large-scale questions - origins of major orders, divergence of major groups of mammals. Some of it is field work dependent, but a lot of what I hope to do is understand the ecology of where these animals were living. It could lead me to pursue things like isotope chemistry, or functional morphology of dentition - how the shape, form of a tooth relates to its particular function..

Any idea what kind of job you'll look for when you are finished with graduate school?

I'm at a crossroads right now. I don't what to have to choose between doing research and teaching and reaching the public. My ideal job would be a place where I could teach introductory level biology courses as well as advanced classes in evolution and paleontology. But it is also important to me to be able to participate in public outreach programs and still be able to do field work and research.

Any other expeditions on the horizon?

I'm really excited about an upcoming six-week expedition to the Late Cretaceous of India that will take place in January 2001. It will be smaller team than this one - both my brother Jeff and Paul (Sereno) will be part of it. India was a subcontinent during this time period and so it may have a similar biogeographical story as Africa and Madagascar. It's another great chance to look for early mammals!

Greg and Hans relax after a very long day of breaking down camp and loading virtually everything onto a large truck