So I must apologize for my lack of updates over the past month, but I just returned from a month long trip to the Montana and Wyoming area for field work (and a week of touring Yellowstone and Glacier National Parks, which were incredible, by the way) and I really didn’t have access to the internet during the trip. While there, I was able to locate and sample five microsites during my field work only one less than my intended number of six. I think I vastly underestimated the amount of time it would take to locate, record, and sample each microsite, so I was lucky to come away with five and not less. Of the five sites, I interpreted two to be of lacustrine (or pond/lake) origin and the three others were interpreted to be deposited in fluvial (river) environments. While in the field, I recorded the geology I observed at each of the microsites that I had found (to make a resonable and applicable interpretation of depositional environment) and proceeded to collect a 40 lb sample of rock from each, which are in the process of being disaggregated and sieved with .5 mm screen. In addition to the 5 microsites, I also collected one 40 lb surface sample (of fossils/sediment that already weathered out of formation from my third microsite (HC 10.03)) to compare how biased surface sampling can be, as opposed to quarrying directly out of the formation. It is commonly hypothesized that that surface collecting will significantly bias results because smaller, more fragile fossils are likely to be destroyed, though this has never been published in the scientific literature. I also collected multiple gallon-sized samples (~5 lbs) from each site to try and map spacial and temporal variability and sediment samples from each site, hoping to provide more evidence for the depositional environments.
My name is Sean Moran and I am a rising senior geology major/biology minor at the College. About 2 summers ago I grew interested in particularly diverse vertebrate fossil accumulations commonly found in the Mesozoic Era (~250 to 65 million years ago). These “microsites” as they are commonly called, contain fossils of a large amount of taxa and, therefore, provide a fantastic representation of the paleoecology of the area where the sites were deposited. Fossils ranging from dinosaur teeth, turtle carapace fragments, reptilian teeth and jaws, fish scales, to assorted vertebrae and limb bones are commonly found. Although the deposition of these accumulations has been heavily debated over the past few decades, a study published within the last few months suggested that they are first deposited in lacustrine (lake/stream) environments and commonly reworked by fluvial or river processes. Unfortunately, because these microsites are usually found in rock formations that contain more “interesting” fossil specimens (dinosaur skeletons, early mammals, etc.), the importance of these sites have been largely ignored in the scientific literature.