The "fossils" of Pipestone National Monument

This is being posted on Halloween, which is fitting for a topic that lingers like a ghost in the literature. Even today, you can still find stray references to the fossils of Pipestone National Monument. "Occasional small trilobites - Lingula, Paradoxides" sounds promising, doesn't it? If you're reasonably familiar with the fossils of Minnesota, you may be wondering why you never heard of this before. There's a pretty good reason: these forgotten fossils are not trilobites or brachiopods, and odds are they are not fossils at all.

Minnesota's dinosaurs

The stats for Equatorial Minnesota have recently shown visitors looking for "Minnesota dinosaur", no doubt because of the recent announcement of a ~90 million-year-old theropod claw from Hill Annex Mine State Park on the Iron Range. Minnesota, as you might know, is not noted for its dinosaur fossils. (I usually have to add the modifier "non-avian" or "classic" to "dinosaur", but I don't know of any bird fossils, either, unless you want to count refuse bones from archeological sites. Maybe the St. Peter Sandstone holds a buried Pleistocene-age cave in a filled river channel somewhere...) However, there are a handful of reports of Cretaceous dinosaurs from Minnesota.

Algae and not-algae

The last of the fossils to be covered to complete the Upper Ordovician Twin Cities set (barring some microfossils and real rarities) are a nebulous group of oft-times enigmatic organisms that either are algae, or have been classified as algae. "Algae" is a much more problematic a term than you might suspect. To put it simply, "algae" is more of a state of mind than a formal classification. At its broadest, "algae" covers basically anything that does photosynthesis and doesn't have the obvious distinct tissues of derived plants, like leaves and roots. This would include anything from diverse microbes to seaweeds. While this has some utility for back-of-the-envelope things, it is not the most useful term for serious classification. It should not be surprising that untold numbers of fossils have been been classified as algae, and that many of these "algae" belong to disparate groups, some of which still have unsettled classifications. About a half-dozen taxa from the Platteville, Decorah, and basal Cummingsville formations have fallen into the "algae" bin at one time or another. They include the following:

The Compact Thescelosaurus

National Fossil Day is this Wednesday, October 14th. The 16th birthday of Thescelosaurus would have been last Wednesday, October 7th. In honor of both, here is The Compact Thescelosaurus, a sortable spreadsheet of basic information on classic (non-avian) dinosaur species, minus names that have not been formally described. I began working on it shortly after I decided to end the website; I still wanted the information to be available, but I also wanted something that was lower-maintenance, and more flexible to edit. This is what I came up with. The other nice thing about it was that I updated a number of things, which I can now use to clean up my original files and perhaps make them available as pdfs, for people who miss the dry commentary and the nomina nuda. This wouldn't happen for several more months, though. Anyway, here's a short user guide to the spreadsheet below the jump, column by column. If someone wants to use the format for some other group, they are free to do so. Otherwise, have fun!

[A quick note, 2015-10-12: I've received a couple of inquiries about being added as editors. I appreciate the interest, but at this time, I'd prefer to keep this project under one person. Feel free to send corrections and other information, though! (I consider many aspects of taxonomy to be matters of judgement, so we many have to agree to disagree on those matters.)]

Conodonts

A common yet easily overlooked type of fossil is the conodont (or "conodont element", should we choose to be picky and/or technical). They are easy to overlook because they are sub-millimeter-scale fossils, which makes them just barely visible to the naked eye if you look really hard. Most of the time, though, all you can do is to take bulk samples of rock and run them acids to liberate these tiny fossils; conodont fossils are made of calcium phosphate, so they will not be dissolved by some acids that do dissolve calcium carbonate, i.e. limestone. Having dissolved your limestone, you can then inspect the remainder under a microscope. Ideally, you will have some little pointy toothy bits, which are the conodont elements.