Cottage Grove cystoid

I recently paid a return visit to the site in Cottage Grove where I'd previously spotted a few blocks with brachiopods/etc. of the typical Platteville persuasion. While there, a few true outcrops were visible under the snow-free conditions of the so-called winter of December 2023, confirming that the Platteville is indeed at the surface and not just present as lag or buried under a bad toupee of soil and glacial debris. More significant was one of the blocks. See if you can spot what drew my attention:

Any ideas?

How about if we go in closer on the area of interest?

If you answered something along the lines of "the thing near the center that looks kind of like a truncated letter K", you've won! I snapped a couple of pictures thinking it might be echinoderm in origin and moved on. Later, upon reviewing the photos, the rectangular bit below it caught my eye; that definitely looked echinoderm. In fact, there is only one kind of thing it could belong to, as proclaimed by the chevron arrangement of slots on it surface. This is a plate from a rhombiferan cystoid bearing a pore rhomb in a pectinirhomb configuration. ("Of course!" you shout.) (Okay, so I looked up the anatomical terminology). Basically, the slots are vents for the animal's water circulation system.

This rock was obviously a good candidate for further study and photography, so I took some more photos with the hope of doing some taxonomy. Further inspection revealed a couple sharply ridged features similar to the "K", but more weathered.

There's a pretty well-developed one in the upper right, and one that is more poorly exposed near the left side.

When I first noticed the "K", I thought it might be ridges on a crinoid plate, but local crinoid plates don't usually have such sharp ridges. Instead, it turns out that there is a Platteville cystoid that does, Coronocystis durandensis. Coincidentally, this particular cystoid also has pore rhombs that are a good match for the pore rhomb plate on this rock (see photos in Kolata 2021).

Here close-up and with a tiny drip of water applied. There is also a gray rectangular ridge visible near the right border that I suspect to be another plate, but it's not as well-exposed.

I hesitate to make a firm identification from the available material, but it certainly appears that we have Coronocystis or something very similar. Coronocystis is interpreted as a stalked rhombiferan cystoid, unlike its free-thrashing cousin Pleurocystities (which does pore rhombs differently and has softer ridges). I interpret the block as from the Mifflin Member of the Platteville, but I suppose it could be higher. Whatever the exact identification at the genus or species level, this is clearly a rhombiferan cystoid, and the first I've ever seen in the field (and I'm pretty sure the first record from Cottage Grove). Plus, the several bits suggest a disarticulated but fairly associated specimen.

References

Kolata, D. R. 2021. Fossils of the Upper Ordovician Platteville Formation in the upper Midwest USA: an overview. Illinois State Geological Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, Illinois. Bulletin 108.

Your Friends The Titanosaurs: Bustingorrytitan shiva

In terms of dinosaurs, 2023 is going to go out like it came in: with a new plus-sized Huincul Formation titanosaur. This one has been delivered just in time for Christmas, although it's unlikely to fit under anyone's tree. Of course, there have been some comments that it is not as big as has been published, but regular readers will know not to get too wrapped up in these things.

10 years of Equatorial Minnesota

So... turns out I've been doing this 10 years. The very first post on Equatorial Minnesota went out December 15, 2013. Here we are, 409 posts and one surprisingly sprawling Compact Thescelosaurus later. I'm hoping there will be many more posts to come, because I still have many ideas, even if the pace has slowed down (lots of other things going on).

For fun, here are some posts from the first five full years that I'm particularly fond of, for various reasons:

2014:

• Practical guide to to MNNRA/metro-area bedrock geology
  
• "The generic history of dinosaur paleontology" series (final part)
• Sponge detective: when faunal lists go bad
• A brief history of dinosaurs on the Internet
• Designasaurus II

2015:

• Historic Twin Cities geologic maps and photos
• Reports of gut contents in herbivorous dinosaurs
• "Where are they now" series (final part)
• Coming Attractions in Dinosauria?
• Nodosaurus: more than a corduroy armadillo 

2016:

• A tale of two packrat species
  
• Gonioceras: when a nautiloid is also a shovel-flounder
• Cambrian island-hopping at Taylors Falls
• Stegopelta
  
• A locked dinosaur mystery
• (former) Ash beds in St. Paul
• The Great Minnesota Brachiopod Caper of 1892
• Club Late Ordovician

2017:

• George William Featherstonhaugh
• Further adventures in the Mazomanie
• The limitations of the layer cake
• Follow-up: Pipestone National Monument, Scenella, Cylindrocoelia
  
• 75 years of "Hadrosaurian Dinosaurs of North America"
• Life on Mill Street

2018:

• Practical guide to St. Croix Valley sedimentary formations
• Titanosaurs all the way down, the start of the ongoing series 
• Identifying invertebrate fossils
• Fun with nautiloids: an essay in futility
• Big Ordovician brachiopods: Strophomena and friends
• Lower Decorah trilobites
• Dryosaurus elderae and the revenge of Nanosaurus agilis
• Rebbachisauridae
• Decorah gastropods (and some things that look like gastropods)

Release the robotic Pleurocystites!

Speaking of paleobiology, here's a fun story that crossed my desk recently...

If you've ever seen a fossil of Pleurocystites or its ilk, you've probably wondered what the heck it was doing in life (and perhaps how disturbing it may have looked while doing it). What once was confined to the realm of speculation now takes a step, or more accurately a kind of thrash, into the 21st century with the "Rhombot", a robotic pleurocystitid detailed in Desatnik et al. (2023).

The rhombots use the basic form of a pleurocystitid: central capsular body (theca), two short appendages (brachioles) at one end, one long appendage (stem) at the other end. The body plan is scaled-up in comparison to the real thing, and, of course, it is made of various artificial materials (many of which are not rigid, hence the "soft robotics" tag) rather than pleurocystitid stuff.

Pleurocystitids, thrashing their way from Ordovician seafloors to the modern day via the rhombot (Figure 1, Desatnik et al. 2023) (CC BY-NC-ND-4.0).

Granted, a rhombot is not a direct replica of a Pleurocystites. Assuming the living thing did indeed use its stem for propulsion, what can we gather from a robotic equivalent? First off, the rhombot was much more efficient with the stem moving it from behind rather than pulling it along. (This seems like a common-sense conclusion on first principles, so it's good to see it confirmed.) The stem also was more effective when used with a stiff sweep, rather than working with a sinuous motion. Finally, there was an optimal length for the stem (Desatnik et al. 2023). I encourage you to go to the linked article and see the movies of rhombots in action; they are not the most graceful robots, but pleurocystitids were probably not the most graceful animals.

References

Desatnik, R., Z. J. Patterson, P. Gorzelak, S. Zamorad, P. LeDuca, and C. Majidi. 2023. Soft robotics informs how an early echinoderm moved. Proceedings of the National Academy of Sciences 120(46):e2306580120. doi: https://doi.org/10.1073/pnas.2306580120.

On the functioning of Thescelosaurus

While it may seem that every paper on dinosaur paleobiology is about Tyrannosaurus rex, or at least some kind of theropod, this is not true; occasionally one slips out on a sauropodomorph or ornithischian. In the past few weeks, in fact, two have come out on aspects of our old favorite Thescelosaurus. Both feature North Carolina Museum of Natural Sciences (NCSM) 15728, also known as "Willo" (the one formerly thought to have a fossil heart). The earlier of the two, Senter and Mackey (2023), considers what Thescelosaurus could do with its arms, and the more recent, Button and Zanno (2023), sheds light on what may have been going on inside of its sharply pointed skull.

Your Friends The Titanosaurs: Inawentu oslatus

Our latest guest in the series is Inawentu oslatus from the middle Late Cretaceous of Argentina. I. oslatus is more than your average new titanosaur; it is one of the two major unnamed titanosaurs discussed a couple of years back, MAU-Pv-LI-595. This is the more recently discovered of the two skull-bearing titanosaurs from Rincón de los Sauces (the other is MAU-Pv-AC-01).

Fossils at Airports

This year's annual Society of Vertebrate Paleontology meeting was held in Cincinnati, and I was quite pleased to be greeted in Concourse B of Cincinnati/Northern Kentucky Airport by a mastodon skeleton.

This seemed like a good omen.

This is hardly the only airport to have fossils. Sometimes they are part of the building stone; at Minneapolis–St. Paul International Airport, for example, you can hardly walk around without seeing fossils in the (non-local) flooring stone. Most of the fossils are bits and pieces of shells, but there are some nice coiled cephalopods, and if you have time they're certainly worth a pause. (It would be fun to do a thorough photographic inventory, but I imagine it would probably have to be explained so as not to appear nefarious.)

Two cephalopods with part of my foot for scale.

A generous assortment of large fossil debris.

In other cases the fossils are on display, as at Cincinnati. One of my favorite examples is the Brachiosaurus at Chicago O'Hare. I've become fairly familiar with this mount over the years since I first saw it on the way to Mongolia, as O'Hare has been practically a required stop on my trips east from MSP.

On this visit in 2019 the brachiosaur was decked out in Chicago Bears livery for the NFL's centenary.

Back to Cincinnati. (Well, not literally; the airport is actually across the Ohio River in Kentucky.) In the mastodon photo above another skeleton can be seen in the distance. I'd been in a hurry when I arrived, so I hadn't explored farther, but made it a point to do so when I departed. It turned out there were five more mounts in the concourse, which makes me wonder if there were any in Concourse A. The animals chosen for exhibit are all typical Ice Age fauna of the area (in fact, all have been found at Big Bone Lick not too far down the river). One notable absence, if only by name, was the giant beaver Castoroides ohioensis, so I kind of hope there were more in Concourse A.

Cervalces scotti, the "stag-moose"; think of a moose with fancier antlers.

A dire wolf pursues an extinct peccary.

A giant ground sloth; the mounts are convenient to walk around, particularly nice for appreciating the unusual anatomy of this animal.

A Smilodon smiling.