Sunday, July 16, 2017

Follow-up: Pipestone National Monument, Scenella, Cylindrocoelia

Here's a little more information on a few enigmas from previous posts, with some additional photos from the University of Minnesota paleontological collections. First up is Pipestone National Monument's "Lingula calumet", then Scenella, and finally Cylindrocoelia minnesotensis.

Sunday, July 2, 2017

National Park Service dinosaurs

Here we are, three and a half years into this thing, and I haven't done a summary of National Park Service dinosaurs (non-avian variety)? No better time than the Fourth of July!

Time for another giant caption! This map shows the National Park Service units where non-avian dinosaur bones or tracks have been found in situ, or are historically associated with a park. 1. Yellowstone National Park; 2. Bighorn Canyon National Recreation Area; 3. Dinosaur National Monument; 4. Capitol Reef NP; 5. Arches NP; 6. Canyonlands NP; 7. Bryce Canyon NP; 8. Zion NP; 9. Glen Canyon NRA; 10. Rainbow Bridge NM; 11. Pipe Spring NM; 12. Petrified Forest NP; 13. Colorado NM; 14. Curecanti NRA; 15. Mesa Verde NP; 16. Chaco Culture National Historical Park; 17. Yukon-Charley Rivers National Preserve; 18. Denali NP & Preserve; 19. Wrangell-St. Elias NP & Preserve; 20. Katmai NP & Preserve (possibly); 21. Aniakchak NM & Preserve; 22. Big Bend NP; 23. Lewis and Clark National Historic Trail; 24. Springfield Armory National Historic Site.

Sunday, June 25, 2017

Dikelocephalus minnesotensis

Investigating the rocks of Saint Croix National Scenic Riverway (SACN) is a tougher nut than working in MNRRA. Most of the area where rocks are exposed in MNRRA is part of some kind of park (city, state, regional, county, etc.) and generally accessible to the public. Much of the area with outcrops on the St. Croix is private land, and many of the key localities in the literature are now overgrown, destroyed by construction, or are roadcuts next to busy highways. Determining where you are in the strat column is also more difficult. In MNRRA, it's hard to get mixed up if you can tell sandstone from limestone/dolomite and shale. In SACN, you're dealing with several quartz-rich medium to coarse sandstones that tend to look the same, with some intervening shaly, dolomitic, or finer-grained sandy formations, and in the literature practically every single investigator had their own preferred system of names right up until the 1960s. Finally, in MNRRA there are abundant and diverse fossils in the Platteville and Decorah, while in SACN the special of the day is the BLT (burrows, lophophorates [brachiopods and hyoliths], and trilobites) with a side order of mystery snails, and you have to work for everything but the B.

The sweet siren song of the Franconian trilobite.

Sunday, June 18, 2017

When brachiopods ruled the Earth

...well, maybe that's an overstatement, but it's a catchier title than "When brachiopods were dominant marine fauna in parts of cratonic North America", right? Our story today goes back to the latter part of the Cambrian, 500 million years ago or so. The Cambrian Explosion had come and gone, the confetti and stray napkins had been disposed of by various wormy things, and in the absence of thumbs to twiddle, there was nothing much to do until the Ordovician Radiation. Many forms of life got bored of waiting and went extinct, or otherwise died out from less frivolous causes, leaving behind a kind of "blah" marine fauna dominated by brachiopods, trilobites, and conodonts. This stretch of time has been called the "Late Cambrian plateau" or, more ominously, a "dead interval".

"We are your masters now! Ha ha!"

Sunday, June 11, 2017

Hoplitosaurus

With the recent coverage of Zuul and the Suncor nodosaur, it seems like a good time for another entry on North American armored dinosaurs. We've already visited with Nodosaurus textilis, Stegopelta landerensis, and Hierosaurus sternbergii. Today's star is another species of similar vintage, Hoplitosaurus marshi. Like our other three subjects, Hoplitosaurus was initially described around the turn of the 20th century from a single armor-heavy specimen found in Cretaceous rocks of the American West. Also like the other three, Hoplitosaurus received barely a blurb for its initial description and had to wait for someone else to spare a little more time and ink.

Sunday, May 28, 2017

NPS Paleontology Roundup

In honor of the return of the Park Paleontology newsletter, I thought I'd do a roundup of some recent articles that discuss fossils from NPS lands. First, though, a word about the newsletter itself. The original incarnation was published from 1998 to 2004, and its archives can be accessed here [note, 2017/06/27: no longer available]. It was intended for brief communications about various topics relevant to NPS paleontology, from new finds, to new staff, to new legislation. The new edition follows in that tradition, with articles on a new exhibit at Big Bend National Park, type specimens from NPS units (yet again, sorry), Emily Thorpe's work at Salinas Pueblo Missions National Monument, which I plugged last post, John Day Fossil Beds National Monument's new Chief Paleontologist Nick Famoso, dinosaur tracks at Rio Grande Wild and Scenic River, and the history of the newsletter itself. If you're curious, yes, the number of fossil species named/possibly named/etc. from NPS units is now at 4,922, thanks in part to the subject of the heading immediately after the jump.

The part and counterpart of University of Minnesota Paleontology Collections 4090, holotype of graptolite Dictyonema minnesotense Ruedemann 1933, collected from the St. Lawrence Formation at a no-longer extant site in Afton, Minnesota, now within Saint Croix National Scenic Riverway.

Tuesday, May 23, 2017

When to stay away from outcrops and exposures

Some recent events have provided photographic fodder for a brief unscheduled revisit of safety concerns in the rocks of the Twin Cities, but first I am going to plug the reborn Park Paleontology newsletter. I'll hit it some more this weekend in more detail, but I particularly want to call out Chapter 3 by Emily Thorpe, who was a Geoscientists in the Parks intern over the winter at Salinas Pueblo Missions National Monument. Among other discoveries, she's got the first vertebrate from the Yeso Group (Arroyo de Alamillo Formation), the part and counterpart articulated back half of a skeleton. We've had a lot of great projects from GIPs the past few years, and I'd strongly encourage college students in the geosciences to have a look when the next batch of positions comes out.

Meanwhile, back in the Ordovician...

You may remember the following photo from this post, or this post. Coincidentally, in both posts the photo is being used as an example of a hazard. It was taken back in June 2013 along the road into Crosby Farm Regional Park, before you get to Watergate Marina.

I wonder where this is going...

If you take that road today (May 2017), this is what you'll see:

...the answer appears to be "down".

This is why you should not stand too close to the walls of the bluffs, or to the edge on top.

Meanwhile, over at Shadow Falls, the Decorah Shale presents a different issue, one that can be expressed as a recipe titled "Reconstituted Ordovician Seafloor": take a hillslope of weathered marine shale, and over the course of six days add nearly five inches of rain. It's amazing!

Hiking boots? More like cleats.

The running water is Nature's subtle way of telling you to stay off.

It's not the mud itself that's the big problem (unless you hate mud, in which case you're really in the wrong place), but the slippery sloppy footing. If you go over into the ravine, it's not going to be easy to get you out!