Re-posted from the BioRx blog – http://wp.me/p4PfB2-1f
I finally had the chance to evaluate my sediment samples that we collected from the Flint Hills last week (I may or may not have been missing a PD meeting at the time… I was eager). The beautiful sediment striation made me think that surely there would be some great micro-fossils in the soil.
Sadly, the dirt in the area is almost entirely eroded rock. Under the microscope it looks almost like brown sugar. It is possible to see where water bubbles had formed as the dirt was repacked after the weathering, which would allow some discussion with students, but nothing more substantial. I was initially disappointed. Then…
Well that is certainly something! I cleaned the subject with a small painting brush from which I had cut/plucked most of the bristles for a very fine point. I used the brush and a wire probe (an inoculation loop with the loop snipped off using metal nips) to center the find and turn it over. Here is what I saw after the preparation:
I wanted to jump to a trilobite identification, but something was bothering me. This shape looked too familiar. I spoke with a couple colleagues in my department, and no one could make a confident identification. I worried that these remains may be a pill bug carapace that had been sun-bleached. My department chair suggested that I evaluate the hardness of the sample, because fossilized remains should be harder (due to their replacement of many constituent substances with sediment) while more recent remains should be frail and brittle. Using forceps I performed this evaluation and found that indeed the sample was highly fragile and was destroyed quickly during manipulation. Ultimately I was left with one confirmed fossil in the entirety of my new collection.
Despite the low density of “keepers”, this exercise would have been great for students. Acting on an informed prediction, testing a sample with multiple explanations, and ultimately confirming the less desirable explanation but still contributing to the understanding of the location are all a big part of the scientific process. I will have to look elsewhere for local sources of fossils, but my understanding of the area is more complete now and I had a ton of fun doing some real paleontology.