On the windblown and weathered surface of the Spring Creek Preserve, belemnites and vertebrae from dinosaurs litter the ground. It is easy to focus on the sheer wonder of finding a fossil, then another, then a cluster, transporting you back to the times of the Jurassic or the ancient seas that once covered Wyoming. To me, the wonder is in the rocks that they’re found in.
In coarser sedimentary rock units in the Morrison Formation, there are fragments and shards of dinosaur bones. As you move into finer-grained sandstone layers, you can find chunks of bone as big as your fist and in some spots chains of fossils representing a limb or a tail. Both the condition of the bone and the characteristics of the rock layers they’re associated with tell a story about an ancient ecosystem. The coarse pebbles of conglomerate rocks, together with shattered bits of bone, indicate how much energy a long-dead river possessed. The finer, more uniform grains in a sandstone and larger, intact bones suggest calmer waters where only smaller particles can be transported downstream and dead creatures can be delicately buried in the stream bed.
Seeing these ancient environments has made me appreciate modern environmental processes so much more. When we study modern ecological communities, I am constantly thinking about the lessons that rocks teach us. The shifts in rock type, even within one geologic formation like the Morrison, tell us that no environment is entirely stable. Slight shifts in atmospheric CO2 or oxygen availability or water pH can dramatically change an ecosystem, from the types of organisms present to what form elements occur in. It seems easier to analyze these shifts in modern environments because we have so much data, whether it be collected by academic researchers, government agencies, or citizen scientists, about the world we live in today. But that wealth of information can be overwhelming at times because it displays so many interactions all at once. Even doing field work, I want to look at everything all the time, and it becomes difficult to focus on the relationships I’m supposed to be studying.
Geology and paleontology are just as complex as modern ecology, but looking at traces of ancient ecosystems in rocks allows you to focus on a few details at a time, especially if you only know the basics about rocks and fossils. The presence of fossilized bivalve shells, filter feeders, in a rock unit tell us that the water was moving and not very silty. A red-colored sandstone indicates an abundance of iron and an oxidizing environment. Even in modern ecology, we look for indicators and patterns to draw conclusions about the world around us. We count and identify macroinvertebrates like mayflies and caddisflies to assess the health of a stream. We map plant communities and use them to draw conclusions about the distribution of water, wind, nutrients, salts, and other elements across a landscape. In both ancient and modern ecosystems, we look and we label and we classify and we ask questions and we try to answer them the best we can.
We do this by looking at patterns. These rocks are this color, what could this mean about where they were deposited? Those plants are only so tall, are they grazed upon or is this an adaptation to wind? The trees in this section of forest are all lodgepole pines, why is that? Even though geology, paleontology, and modern ecology take different approaches to understanding the Earth and its systems, they all have something to teach us about how the Earth works and how environments and communities interact and change. You just have to be willing to look and ask questions.
All the best,
One Comment Add yours
This is cool stuff! We’re glad you are getting this opportunity to do this. Keep up the good work! Poppy