Eureka at Cisco

Dr. Brian Davis is an Associate Professor in the Department of Anatomical Sciences and Neurobiology at the University of Louisville School of Medicine where he teaches gross anatomy to medical and dental students. He earned his Ph.D in Zoology from the University of Oklahoma and has been at the University of Louisville since 2013. His primary area of research is craniodental morphology and evolution in early mammals using conventional methods as well as CT scanning. He has been actively involved in field work and fossil collection throughout the American West for over 25 years. His recent focus has been work on small fossils from the Cisco Mammal Quarry in eastern Utah, which he discovered in 2015 while exploring exposures of the Upper Jurassic Morrison Formation.

University of Louisville

Research

Cisco Quarry

Science Moab talks with Brian Davis, a paleontologist that teaches anatomy at a medical school, Brian is an associate professor at the University of Louisville School of Medicine in Louisville, Kentucky, and he works on early mammals…mostly teeth and jaws and parts of skulls. His most recent work on mammal fossils is based in Cisco, Utah.

Science Moab:  You are exploring in the Brushy Basin Member of the Morrison Formation, which is prolific for its preservation of amazing fossils…most notably, the large dinosaur bones.  When you come across a fossil, how do you know if it’s a mammal?

Davis:   Our record of mammals is still pretty poor, partly because they’re not easy to find during the age of dinosaurs and especially in the late Jurassic.

Mammal fossils are all very small and fossilization is a really rough process… it is not kind to animals that are really little and delicate. So we tend to see robust, heavy parts of animals surviving best. So the bigger you are, the heavier and harder your skeleton is, the more likely you are to turn up as a fossil.

When we find mammals, they tend to be the hardest part of the skeleton, which are teeth. So teeth and jaws tend to be the majority of what we find. Occasionally get lucky and you’ll find a little bit of a skull, a couple of pieces articulated here and there, but it’s really rare.  Part of the reason we don’t know a lot about early mammals is that their fossils are exceedingly rare, but they’re also hard to find, which means that they’re easily overlooked. You have to go out looking for mammals to find them. Many of the early records or early finds of mammals were accidental. 

Science Moab:   How did you happen upon the Cisco quarry of mammal remains?

Davis:    At Cisco, I was just wandering my way up little drainages following the occasional little piece of turtle shell or a weathered piece of dinosaur bone hoping to find a horizon where things were weathering out of. I climbed up a drainage to the top of a hill following what I was hoping were a few bits of fossils sticking out of the top of the hill and in the crumbly mudstone surface was a teeny little piece of bone, about half the size of my pinky finger. That was the first piece of bone from the locality.   In cleaning the surface, digging around, we found a couple other ends of bones sticking out of the rock here and there, but it turned out to be a very different little micro habitat and collection environment than I was expecting.

I was expecting to find an accumulation…a lens of small bone that had all been washed in one spot together…but it turned out to represent probably a really quiet, backwater, ephemeral pond of some sort that was maybe only around seasonally.  Maybe it was a local source of water.  The animals that would die in that spot would be preserved there. we tend to find somewhat more complete fossils of small things that haven’t been moved very far, which is really important. The energy of transport tends to break apart all these little animals that I’m interested in finding.

Science Moab:   You began exploring in the Cisco area in 2015 because of its Brushy Basin, outcrops and similarity to what has been discovered right across the border in Fruita, Colorado.  (The area just south of Fruita at the base of Colorado National Monument is famous for small, complete, and really exquisite mammal fossils.)  Have you had a chance to compare the Cisco fossils to what has been found near Fruita?  

Davis:  It seems like the rocks in this little spot that I found near Cisco represent a very similar micro habitat to what is over in the Fruita area.  The record is still pretty incomplete and we’re dealing with animals that lived so long ago that a lot of them are nothing like anything alive today.  I guess it’s not surprising if whatever little micro habitat we’re sampling in Cisco is really similar to Fruita, you’d expect there to be overlaps in the animals found, and that seems to be the case so far.

Science Moab:  What stage is the excavation or exploration of the Cisco quarry?

Davis: There doesn’t seem to be an obvious productive horizon at the Cisco quarry. The bone seems to be everywhere, which is great, but also frustrating. Like any patch of exposed rock on the top of this little hill could be just as good as any other ones. It can be hard to focus on a specific spot. So really it comes down to just working our way through the surface of this little knob and just slowly pushing until we get to the end of the hill then turning around and going another direction for a little while. How much more rock is there to work in the hill? It could stop producing next summer, or it could keep going for 20 years. It’s hard to tell because there’s not an obvious bed that we’re following, but it’s been fairly easy to work because we’re mining the top of this little knob.  So it could be that any little hill nearby could be just as productive or even more productive. 

I may have wasted 10 years on the least productive hill in the area. You just never know.