How do you look into the past? This has been a question that scientists, historians, and everyone in between have been looking to answer since we started keeping time. Many fantastical ideas have been suggested by media, whether it be cloning the dinosaurs and setting them up in a theme park or using a time machine and going straight to the source. While a time machine would be nice (barring all space-time complications and butterfly effects), there is actually a much easier way of going about this question. Take a look at the rocks.
As an ecology student, this would not have been my initial instinct. How can looking at ancient rock formations today tell you about of the ecosystems of the past? Well, now that I am three weeks into this program and have had a variety of field lessons in geology, paleontology, and ecology, I can confidently begin to answer this question. The obvious answer most people would supply is to look at the fossils or just dig up the dinosaur bones. These are both helpful pieces of evidence when it comes to learning about the Earth’s past, but they are not the whole picture. To even begin thinking about fossils, you have to know where to look. This is where knowing your geology is important.
In Wyoming, the current ecosystem is, well, pretty dry. The prairie is full of grasses, sloping hills, and lots of animals from the pronghorn to the prairie dog. From an outside point of view, a place like Spring Creek seems pretty unremarkable, at least until you stumble upon a millions of years old shell or a piece of Dino bone. You would never expect to find a seashell in the middle of the country, thousands of miles from the nearest ocean. Luckily, the geologic history of Wyoming clues us into why that seashell is here. By looking at the rock formations, like the Wall Creek Member, more closely, you begin to see evidence of the ancient seas that once covered the plains. The Western Interior Seaway that once had Spring Creek underwater, left behind a lot for us to find. Rippling and crossbedding in the rock tell us about the once powerful waves and currents that made up the sea. Ammonites, bivalves, and even shark teeth can be found, telling us that the prairies of Wyoming were not only covered in water, but also had a diverse array of aquatic life living in them. This is how we study ancient ecosystems. When we see evidence of water, like with rippling printed into the rock, we know that is likely where we will find evidence of ancient aquatic ecosystems.
Ancient rock can tell us about pretty much any ancient ecosystem that has ever existed. Rock existed before life and it will existed after too. Whether we are looking at ancient fish fossils in the Mowry formation or dinosaur fossils in the Morrison, we always have something to learn from the rock. It can tell us about plant and animal communities, ancient climate, water movement, and so much more. As modern ecosystems continue to change especially due to climate change, it will become important to understand how past ecosystems changed with climate, water, and weather, so that we are better prepared for what is going to happen in the future.
So, to answer the question, how do we look into the past? Rocks are a great place to start.
More later,
Julia
