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.

Compact Thescelosaurus Year Eight

It's that time again, for National Fossil Day (October 11 this year), a new sheet for The Compact Thescelosaurus, and the annual summary of what was added to the spreadsheet in the past 12 months. In addition to National Fossil Day events this month, the latest issue of Park Paleontology News is up for viewing. Also in breaking NPS paleontology news: additional dating of the fossil human tracks at White Sands National Park, and a previously overlooked record of a tyrannosaur tooth at Yellowstone National Park. [Update, 2023/10/10: And a tritylodont bonebed at Glen Canyon National Recreation Area was just announced; goes well with this new paper on a massive track block from the recreation area, too.]

Here at Equatorial Minnesota, we've passed 400 entries this year. Later this year, December 15 will mark 10 years of posting. (Also, anyone know why this nautiloid post would have spiked in interest?) The Compact Thescelosaurus has been around for 8 of those years, and it's traditional to add a new sheet. For this year, first I considered all of Pseudosuchia (except for the aetosaurs, covered already), but decided against it due to the number of species. I then looked at doing just Mesozoic pseudosuchians before being discouraged by whatever it is Thalattosuchia has been doing over the past 200 years. So, for now it's just Triassic forms, with the intent to expand over time.

Prestosuchus threatening an Eoraptor in the "Ultimate Dinosaurs" exhibition at the Science Museum of Minnesota, May 2014.

Your Friends The Titanosaurs: Jiangxititan ganzhouensis

It's that time again, when another titanosaur makes an introduction. Today we have Jiangxititan ganzhouensis, from the late Late Cretaceous of southeastern China. As a disclaimer, I tend to reserve my judgment with East Asian titanosauriforms, who have a tendency to play coy about their phylogenetic relationships. However, J. ganzhouensis is interesting on its own terms, whether or not it is within that charmed circle of "Andesaurus delgadoi + Saltasaurus loricatus".

A lateral view of the type vertebrae of Jiangxititan ganzhouensis, dorsals on left, cervicals on right; scale is 20 cm (8 in) (Figure 3, Mo et al. 2023, which see for legend) (CC BY-NC-ND-4.0).

Fossils of the Upper Ordovician Platteville Formation in the Upper Midwest USA: An Overview

I'm not really in the business of plugging books, but I *have* gotten one recently that those of you who read this blog for the Ordovician posts may find interesting (if you haven't already come across it). The book is "Fossils of the Upper Ordovician Platteville Formation in the Upper Midwest USA: An Overview" by Dennis Kolata, Illinois State Geological Survey emeritus (and also one of the authors on a volume on the Deicke K-bentonite). I was tipped off to it by member "connorp" on The Fossil Forum during my quest to identify what turned out to be Zittelloceras.

The Platteville of Illinois and southern Wisconsin isn't *exactly* the same as in Minnesota (the strata are thicker and the fossils are better preserved than what we see in the Twin Cities), but anyone looking for information or comparative photos for Minnesota Platteville fossils is going to find plenty in the book to consider. The book is also useful for identifying fossils in the overlying rocks (e.g., the Decorah Shale), because many of the genera are the same. Several graphics clarify the correlation of different Platteville divisions across the area where the formation was deposited.

The text, organized by broad taxonomic group, is technical. Each species is given a diagnosis, followed by remarks about aspects such as notable features or distinguishing it from other species, and then its stratigraphic and geographic distribution. This is not unlike the various group-focused articles in Sloan (1987), but unlike the small black-and-white figures in the 1987 book, Kolata's book is filled with gorgeous color plates featuring large photos of every species. (The one quibble I have is that scaling is given by numbers, e.g., "x1.5", instead of scale bars, but I can certainly use them either way!) For anyone who is interested in the fossils but is not versed in the details of invertebrate anatomy, or anyone just looking to identify a particular find, these plates are invaluable.

If you'd like to find out more about this volume, the Illinois State Geological Survey bookstore is online here. The book can also be found on Amazon. It is 316 pages and costs $60.00.

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.

Sloan, R. E., editor. 1987. Middle and Late Ordovician lithostratigraphy and biostratigraphy of the Upper Mississippi Valley. Minnesota Geological Survey, St. Paul, Minnesota. Report of Investigations 35.