Sunday, October 16, 2016

Year One of The Compact Thescelosaurus (now with extra choristoderes)

Mid-October is the time of National Fossil Day, as well as just past the anniversary date of the late lamented Thescelosaurus! and the introduction of The Compact Thescelosaurus. In honor of the occasion, I've made a couple of additions. One is a new page with a selection of online museum collections databases. The other is a new worksheet on The Compact Thescelosaurus, featuring choristoderes. This sheet is the first of what I hope to be a series covering other fossil groups; choristoderes were selected for the honor this time around because there are only a few. I have a few candidates in mind for the next addition, perhaps a year from now; it depends on how ambitious I'm feeling. I haven't given up on the idea of making a version of the old website's contents available, but I haven't really decided how to do it.

So it's not really surprising that I came up with a post on subtle nuances of the nomenclature of Champsosaurus.

Sunday, October 9, 2016

The Platteville Formation revisited

For the person interested in fossils in the Twin Cities, the Decorah Shale is money in the bank. It's a cooking pot that never empties, a gas tank that's always full. If you have a patch of it, you cannot lose. The Platteville Formation is more like a lottery ticket. If you pick up a random piece, the chances are good it will have nothing, or maybe an imperfect brachiopod mold or two, or some "eyelashes" from shells in cross-section, or half of a burrow. Even when you do find a chunk that's loaded with fossils, usually it's 95% brachiopods and 5% snails, with a couple of crinoid columnals, bivalves, or bryozoans for variety. Every so often, though, you will come up with something unusual. It's true that the Decorah also rewards in-depth exploration, but the "floor" of discovery is so much higher in the Decorah that the feeling when you do find something out of the ordinary in the Platteville is much different. It's more of an accomplishment. The universe has rewarded your perseverance, has conspired with taphonomy, lithification, and erosion to put someone with the proper skills and inclination (i.e. you) in this place at this time to observe and appreciate this fossil. (I will refrain from pulling out the conulariid again.)

I've seen a few of these big snails; not sure about the genus yet.

In terms of preservation, the Decorah Shale is a strictly representational artist dedicated to faithful reproduction of the fossils, thanks to relatively mild conditions for fossilization and diagenesis (the stuff that happens during and after the formation of sedimentary rocks, like replacement of calcite with dolomite). Thanks to dolomitization, the Platteville Formation of the Twin Cities Basin is a sort of minimalist impressionist, retaining only some essential essence of a given fossil while losing most of the fine details. (It also has a thing for sparkles, what with all of the fine dolomite crystals.)

And then we've got blocks like these, doing a decent job of imitating the Decorah. I think I can place the source to a specific bed in the upper Mifflin, but it may be very localized.

On Saturday, I was the guest paleontologist for the Second Saturday fossil event at Coldwater Spring. (I'm the tall one with the facial hair.) After having spent a lot of time along the gorge, I think it is fair to say that Coldwater Spring is one of the best places in the Twin Cities to be in close contact with the Platteville Formation, if not the best. It is certainly the best place to take people of all ages and experience levels to see Platteville rocks and fossils. In most locations on the gorge, the Platteville is a brooding presence capping whitish bluffs of St. Peter Sandstone, inaccessible to all but the most reckless. At some places where a ravine joins the gorge, such as Shadow Falls, Minnehaha Falls, and a few locations on the Minneapolis side of the river, you can walk around parts of the Platteville, but you also are stuck on narrow paths where you've got the Platteville on at least one side, sometimes two (the other side is the one above your head), and the steep slope of the bluffs on the other. This can be chancy when you're on your own and is not feasible for groups of non-professionals, and even when you do go, you usually only get to see the lower part of the formation. By virtue of erosion and some human modification, Coldwater Spring allows you to appreciate the Platteville at close range on level ground. The gentle slope of the bike path trail means it's a short walk from the lower Platteville exposed at the south end of the park to the upper Platteville at the north end. This chance alignment also means you can get right next to the contact with the Glenwood at more or less level ground as well. October is also one of the best times to visit: the vegetation is dying back so you can see the rocks, the temperature and humidity are comfortable, mosquitoes and ticks are in retreat, and the ground is is not saturated with spring snowmelt.

The park is also great for these fossil walks because of the fossiliferous building stone and the presence of several areas with lots of small eroded blocks of the Platteville. I can bring families to the building stone used in the parking area and near the Spring House to give them an idea of what the fossils look like, and then the kids can rummage around in the loose stone. It's a great time: if your family is here, you're probably already the kind of kid who likes to rummage around in rocks; the Platteville is a reliable producer of shelly fossils, so everybody should get to see something; there's that paleontologist guy who can tell you what you've found, and if it's really interesting he'll call everybody over to see what it is; and there are also lots of interesting bugs and spiders and so forth if you're striking out on the fossil front, without anything too dangerous (one of the perks of exploring in Minnesota, although we do scare the bejeezus out of many innocent pillbugs). I get lots of questions, and nobody seems to mind that it's "catch and release" here (NPS property). I've been around the rock pile a few times, so I'm jaded. It takes more than a couple of brachiopod molds to get my interest. But if this is your first time to visit fossils in the field, to turn over a rock and maybe be the first person to ever see the brachs on that particular slab, you can't do much better.

First shells!

Sunday, October 2, 2016

Fossil type specimens of the National Parks

I've just returned from the 2016 Geological Society of America annual meeting at Denver, wherein I gave a presentation on our recently updated inventory of paleontological resources in the Mojave Desert Inventory and Monitoring Network. Trying to stuff Death Valley National Park, Great Basin National Park, Lake Mead National Recreation Area, Tule Springs Fossil Beds National Monument, and friends into a sub-15-minute box is an interesting experience. I could have done a semester-long class and still missed some things.

Why, it's a giant blue bear. You don't see that every day, unless of course you live in Denver. It lost its name tag, so they won't let it in.

Sunday, September 18, 2016

Sunday nautiloids

An interesting fact concerning nautiloids and the Platteville Formation is that the biggest nautiloid shells are often found only partially preserved, because their diameters (up to around 10 in/25 cm) exceeded the depth of the Platteville ooze they sunk into (Webers 1972a, 1972b). This means that when you see a fossil of one of these big Platteville nautiloids where the cross-section is partly round and partly irregular, you can guess that the round part represents what was buried; the rest of it was eroded off. So, while a small nautiloid can be completely buried:

...the big guys aren't so lucky. Take these examples from Sogn, Minnesota:

The more impressive of the two, featuring the part that looks like a nautiloid.

The cross-section of this specimen. Round was down (in the mud), originally.

The cross-section of the other, less impressive nautiloid.

Half a nautiloid is better than none, and for these two nautiloids, it permits a bonus: other shells and organic fragments collected in the eroded nautiloids. Notice the off-white patch near the center of the first cross-section above? Here's a close-up:

This is a small lingulid brachiopod (modern cousin Lingula; see a larger relative from Oklahoma rocks of reasonably similar age to the Platteville here). There are several fossils larger than millimeter-sized chips visible on these nautiloids, and they all appear to be the same kind of lingulids. This is an interesting association, but I couldn't tell you what it means. Here are two of the better-preserved examples:


Webers, G. F. 1972a. Paleoecology of the Cambrian and Ordovician strata of Minnesota. Pages 474–484 in P. K. Sims and G. B. Morey, editors. Geology of Minnesota: a centennial volume. Minnesota Geological Survey, St. Paul, Minnesota.

Webers, G. F. 1972b. Paleoecology of the Ordovician strata of southeastern Minnesota. Pages 25–41 in G. F. Webers and G. S. Austin, editors. Field trip guidebook for Paleozoic and Mesozoic rocks of southeastern Minnesota. Minnesota Geological Survey, St. Paul, Minnesota. Guidebook 4.

Sunday, September 11, 2016

Port Kennedy Bone Cave supplement

The National Fossil Day monthly feature for September is Port Kennedy Bone Cave, in Valley Forge National Historical Park. There is a Pleistocene theme this year, and caves are great for Pleistocene fossils. Port Kennedy Cave is the second cave-based feature I've written this year, after Rampart Cave, and the third cave feature total (we've also got Gypsum Cave). We've still got three months to go, and I could certainly see some more caves in there. Anyway, I'm writing this to direct you to a story on an unusual site (you get middle Pleistocene mammals, Edward Drinker Cope, Valley Forge, a rumored buried train, and bone preservation compared to "over-ripe pears"), and provide some supplementary material on the species described from the fissure.

Monday, September 5, 2016

Regarding Liaoningosaurus

By now you may have heard about the new paper by Ji Q. et al. on Liaoningosaurus, proposing some surprising things about the paleobiology of this ankylosaur. Andrea Cau already had a go at it over at Theropoda. I'm afraid I won't be as concise or insightful, but possible gut contents are involved, and having fought my own gut-content dinosaur to a truce, I think I can bring a distinct perspective to this paper. 

Wednesday, August 31, 2016

The Great Minnesota Brachiopod Caper of 1892

I've been looking to write something on Frederick Sardeson for a little while now, but Weiss (2000) has taken care of his biography in great detail, and there's enough going on there that to summarize it would still give you a long, long post. Instead, as I was working this particular incident stood out and volunteered to serve as a microcosm of his career. I present the Great Minnesota Brachiopod Caper of 1892. Weiss (1997) also got there before me, but this is a much more compact bite to take.

First, our cast of characters as they were in 1891–1892:
Christopher Hall, the head of the University of Minnesota's Department of Geology;
Frederick William Sardeson, former law student turned geology graduate student under Hall;
Charles Schuchert and Edward Oscar Ulrich, up-and-coming geologists/paleontologists out of Cincinnati; and
Newton Horace Winchell, the head of the Minnesota Geological and Natural History Survey.

And the situation:
Winchell was not a paleontologist, but he had a lot of fossils. In order to deal with them, he assembled a group of paleo-hotshots. For our purposes, the most significant are Schuchert, a budding brachiopod expert, and Ulrich, who could deal with a wide range of fossil groups. They'd already worked together on projects for the surveys of other states, so were experienced in this line of work. Winchell's team described hundreds of fossil species, with the culmination of their work being the great multi-volume "Geology of Minnesota" series. It is the creation of this series that led to Sardeson getting bluffed out of six brachiopod species by Ulrich and Winchell. For brevity, let us describe the events like this:

  1. Winchell brings in Schuchert to describe the numerous brachiopods.
  2. Hall directs Sardeson to bring Schuchert up to speed on the local brachs. Hall had previously worked with Winchell on the survey and dislikes him, although he is generous enough in this case.
  3. Sardeson and Schuchert have an informal deal that Sardeson will not publish any new brachiopod taxa until Schuchert has his work out.
  4. The "Geology of Minnesota" series is taking a long time to complete. The draft of the brachiopod chapter (Winchell and Schuchert 1895) is pretty much ready to go by late March of 1892, though, and Schuchert leaves town. In the meantime, Sardeson has nearly completed his graduate work, and has prepared a joint publication with Hall on the local Paleozoic rocks. An essential part of this is Sardeson's biostratigraphy, which incorporates a number of undescribed taxa. Hall insists that descriptions be published in advance of the joint paper.
  5. Ulrich finds out that Sardeson is preparing descriptions of new species, including brachiopods, which he promised not to do per point 3. This manuscript will be ready to go by early April. Winchell is not pleased by this turn of events.
  6. Winchell and Ulrich opt to extract part of the manuscript prepared by Schuchert to preempt Sardeson. It just so happens that the Winchell family owns a journal and Winchell himself is the editor (The American Geologist, which later kind of turns into The Pan-American Geologist). This is convenient. However, Sardeson's descriptive work, coincidentally enough due to be published in a journal edited by Hall (Bulletin of the Minnesota Academy of Natural Sciences), is almost ready for publication. There isn't enough time for Winchell and co. to preserve priority, or is there?
  7. Fittingly enough, on April 1, 1892, Ulrich provides Sardeson with a fake preprint of the extracted article, bluffing that it has already been mailed out. This has not happened, and in fact only two copies of the April 1 preprint are known to exist: Sardeson's copy and a copy kept by Ulrich.
  8. Sardeson's own article is mailed out April 6.
  9. An actual preprint of Winchell's article is mailed out April 21, with a note on the title page that it was first distributed April 1, 1892. The note does not explain that the distribution consisted of the single copy supplied to Sardeson.

The immediate result is that perfidy is rewarded, at least as far as Sardeson is concerned; the community takes it at face value that the April 1, 1892 date on the Winchell and Schuchert article is legit. Sardeson is "scooped" on six brachiopods: Orthis minnesotensis, taken by Winchell and Schuchert's Orthis meedsi; Orthis petrae, taken by Orthis proavita; Rhynchonella sancta, taken by Rhynchotrema inaequivalis var. laticostata; Streptorhynchus subsulcatum, taken by Strophomena scofieldi; Strophomena halli, taken by Leptaena charlottae; and Zygospira aquila, taken by Hallina nicolleti. The episode does not reflect well on any of the participants: Hall forced Sardeson into the mess, Sardeson broke his word to Schuchert, and Winchell, Ulrich, and to a lesser extent Schuchert came up with a new twist on the time-honored game of "screw over the grad student". For good measure, Winchell's team also appropriated the framework of Sardeson's biostratigraphic zones without giving him much credit. In the long run, the episode blows over as another quaint example of academic hardball. Hall is more or less forgotten today. Schuchert works with the U.S. Geological Survey and the National Museum of Natural History before moving on to Yale for the long term, where he becomes the god of brachiopods and eventually makes up with Sardeson. Ulrich goes on to the USGS, where he continues working on the lower Paleozoic and unsuccessfully proposes two additional periods out of the Cambrian and Ordovician (the Ozarkian and Canadian). Winchell successfully guides the Survey work to completion, retires to archeology, gets a number of things named after him, and is now more or less the only geologist based out of Minnesota that anyone has ever heard of. Sardeson embarks on a tempestuous career.

Sardeson was the one left holding the bag, which becomes something of a pattern for him. He was a fascinating paleontologist who combined aspects of 19th century heroic geology with brilliant insights on topics such as paleobiology, paleoecology, and biostratigraphy, along with very un-19th-century ideas on when to name new species. Over several decades he amassed a collection of thousands of fossils from the Ordovician of Minnesota, carefully plotted stratigraphically. Unfortunately, for all of his gifts, he also had an uncanny knack for marginalizing himself through sarcasm, paranoia, and professional contempt. (I'm not going to get into chicken-and-egg, but the events of 1892 probably did not increase his trust in others.) He quarreled with most of the geologists he encountered and entered into several long-running feuds which, despite whatever justification, did him more harm than good. He came up with the earliest name for what we now call the Platteville Formation and Decorah Shale (Beloit Formation, 1896), but was ignored in favor of the Platteville Formation, coined years later by a USGS geologist (Bain 1905). He was prevented from working on the geology of the St. Croix Valley by Ulrich and Charles Walcott (not counting the fact that Sardeson and Ulrich were not exactly buddies, Ulrich had staked out that area as part of his turf, and Walcott was wary of anyone who might show him up in his Cambrian sections, and Sardeson did not mind showing people up). He was dismissed from the University of Minnesota in 1913 and ended up blacklisted from all of the geology journals except the eccentric Pan-American Geologist. Through it all, he displayed superhuman perseverance. He was publishing up to 1940, into his 70s.


Bain, H. F. 1905. Zinc and lead deposits of northwestern Illinois. U.S. Geological Survey, Washington, D.C. Bulletin 246.

Sardeson, F. W. 1892. The range and distribution of the lower Silurian fauna of Minnesota with descriptions of some new species. Bulletin of the Minnesota Academy of Natural Sciences 3(3):326–343, 408–413.

Sardeson, F. W. 1896. The Galena and Maquoketa shales. Part 1. American Geologist 18:356–368.

Weiss, M. P. 1997. Falsifying priority of species names: a fraud of 1892. Earth Sciences History 16:21–32.

Weiss, M. P. 2000. Frederick William Sardeson, geologist 1866–1958. Minnesota Geological Survey, St. Paul, Minnesota. Bulletin 48.

Winchell, N. H., and C. Schuchert. 1892. Preliminary descriptions of new Brachiopoda from the Trenton and Hudson River groups of Minnesota. The American Geologist 9:285–294.

Winchell, N. H., and C. Schuchert. 1895. Sponges, graptolites, and corals from the Lower Silurian in Minnesota. Pages 55–95 in Lesquereux, L., C. Schuchert, A. Woodward, E. Ulrich, B. Thomas, and N. H. Winchell. The geology of Minnesota. Minnesota Geological and Natural History Survey, Final Report 3(1). Johnson, Smith & Harrison, state printers, Minneapolis, Minnesota.