Wyoming Spring Creek: Piecing Together the Past

Ecology is first and foremost a science based upon observation. Environments biotic and abiotic factors are copiously described in detail, organismal behavioral relationships are watched and recorded, surveys are designed to count biodiversity and abundance, and individuals are analyzed and marked to gather data on community health and watch populations into the future. All of this work goes into comprehending the interrelations within entire ecosystems that allow us to view how the natural world functions and how different actions may affect it into the future.

However, ancient ecosystems are harder to piece together as our knowledge of them is based solely upon what makes it into the fossil record. Over the course of our explorations into paleo-geology, we were introduced to taphonomy, the study of fossilization that encompasses everything that happens from the moment the organism has died to its discovery and preservation in a museum. One thing that most people may not consider due to the saturation of dinosaurs into the collective cultural consciousness and sheer amount of knowledge that we have of the fossilized past, is how difficult and miraculous it truly is to be preserved in time. Each step of the process is limited by “filters” or factors that are possible obstacles to fossilization such as predation within that time period, erosional circumstances such as wind or water, rock type the specimen is deposited in, the anatomy of the organism and whether its has hard or soft tissues that compose its body as most discoveries are of bones rather than skin or hair. Our knowledge of the ecological systems and organisms that inhabit them is based completely on what scientists observe within the written record of the Earth, meaning that the collective knowledge of the past is far from complete as it is possible that hundreds of organisms and behaviors to have never been recorded as they weren’t suitable to fossilization. 

One may ask then how can we be sure that the conclusions that we have drawn about the past are accurate? The answer, Earth typically works in patterns and organisms often have a traceable evolutionary lineage that helps us to infer more accurate pictures of their ancestors and the environment in which they lived. As we have studied modern marine environments we can infer information about ancient seaways like the Western Interior Seaway even from what is noticeably absent from the fossil record. For example, in the time of the Mowry Formation, we can conclude that the waters were more acidic as there is an obvious lack of benthic, shell forming organisms that live at the bottom of the sea which we know have been recorded before and after the time of this particular depositional formation, since a lower pH prohibits that availability of calcium carbonate for these organisms to form their shells and stimulates dissolution of this shells in the long term as acid breaks apart this molecule. Past records combined with our understanding of present environments and organisms allows us to decipher the fossil glyphs that Mother Nature has left for us to interpret. For instance, the present organisms that we are dearly familiar with have all evolved from the fauna of the past. Birds have evolved from theropods, a group of bipedal dinosaurs, that similarly have feathers, egg brooding, light bones, and three toed feet having a modern comparative to these anatomical structures and behaviors allows for scientists to better evaluate the life mode, conditions in which they lived, and the chronological development/evolution of functions such as flight. By observing the present to reflect on the past the ecological systems of both periods may be elucidated. 

Ammonite fossil within the Wall Creek Formation, different types of organisms and rock types help define the conditions in which they were deposited. As this ammonites is a marine creatures and was deposited in quartz sandstone with ripple marks (usually caused by waves or a current) present, it may be inferred that the depositional environment is that of a shallow beach area.

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