A question that has been running through my mind recently is, how can we know if we've adequately sampled a formation for fossils? I know that biology has various methods for doing this, such as rarefaction curves, but I also am aware that paleontology presents its own unique problems in applying those concepts.
What's driving this is the requirements for paleontological resources preservation. One criteria for evaluating whether a formation is sensitive is the probability that it will produce a new type specimen--ie, a new species. If we can evaluate completeness of past sampling, we can get a handle on this. This won't affect formations that produce vertebrate faunas (inherently scientifically significant per the SVP/BLM), but it will strengthen the argument for monitoring formations that have produced predominantly invertebrate remains.
Are there any good references for looking at this sort of question?
Yes, there is a long list of studies on the effects of uneven sampling, amount and depositional setting of rock preserved from a certain geological time slice, so-called "lagerstätten effects" (peaks in diversity due to exceptional preservation), effects of better preservation of and knowledge about younger to recent groups ("pull of the recent") and so forth. See e.g.
https://www.researchgate.net/search.Search.html?query=fossil%20record%20%22sampling%20bias%22&type=publication
These questions came up in the 1980s when researchers became more active in their attempts to measure palaeodiversities. Some methods from "neontology", such as rarefaction curves, have been adopted.
Thanks! It's good to see a paper on ichthyosaurs in that list--I was thinking they would be a fantastic resource for this, and it confirms that I was at least on the right track.
I'm not so much interested in understanding the degree to which our sample represents the ecosystem. I'm more interested in knowing whether or not a formation has been adequately sampled. The question stems, as I said, from paleontological resources monitoring/mitigation legislation--many regulations I've come across call for preserving scientifically significant fossils, and most of the time that de facto ends up meaning vertebrates (minus fish). I think a reasonable argument could be made that in poorly-sampled outcrops even invertebrates may be significant. That legislation is all based on the geological formation.
My thinking is that if we treat monitoring as a sampling effort within a larger historic context, we can make a more accurate determination of the probability of even invertebrate remains (macro and micro) contributing significantly to our understanding. In poorly sampled formations any new information may be significant; in well-sampled formations additional sampling isn't likely to tell us much, and the invertebrates are less likely to be significant. While this may seem harsh, right now invertebrates are largely written off in this work, so even this would be a substantive improvement.
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