Bivalves

The clam. The oyster. The scallop. The mussel. These are not just names suitable for a low-rank themed superhero or supervillain, but they are also common terms used for some of the abundant and diverse members of the class Bivalvia (also known as Pelecypoda in some references, and Lamellibranchiata if you go back far enough or have a desire to be "that person"). We've already seen the difference between the functional and technical usage of the term "bivalve" with brachiopods, now we get the bivalves that "are" bivalves.

Thescelosaurus: 1999–2015

After about 15 and a half years, I'm no longer going to be maintaining Thescelosaurus.com, expiration date April 9, 2015. It was just one of those things, with a number of reasons behind it. The main one is that I didn't know why I was doing it any more. I'd long ago stopped doing it out of enjoyment and had been doing it out of a sense of obligation. The field of dinosaur paleontology had passed me by years ago, beginning after my graduation from the University of Colorado at Boulder, so I was doing it for enjoyment, and if I wasn't enjoying it, what was the point? The quality of the content was never that hot (I'm not going to claim it was great at the beginning and then declined, because a lot of the initial stuff was pretty hare-brained). As the years went on, the seams resulting from cobbling on this and that were showing, the actual "physical plant" (or whatever the equivalent is for a website) was beyond archaic, and I didn't have the time or, in the end, the desire to bring it up to code. Finally, every year it got a little more expensive, and given the small readership, it occurred to me that I could hear myself talk at cheaper rates.

You'll still be able to find archived versions at Internet Archive, using http://www.thescelosaurus.com/ [later comment: although be very, very careful, because the domain was purchased by other people over the years; the only archives you can be sure are mine predate April 2015, and even then sometimes you get redirected to a more recent version that is very much not mine!], or if you're really desperate, I'm still going to be holding on to the files. Maybe I'll add to them; I don't know. As for alternative sources, I recommend the dinosaur articles at Wikipedia, which at the very least are on par with my own entries and usually much better (and include sources of information), and the Supplementary Information for Thomas R. Holtz, Jr.'s encyclopedia. In particular, the updated versions of the genera list are like mine, only much better. You're welcome to copy the pages for your own use, but I don't want someone else to continue the website because of my concerns with the quality of the content.

I'd like to thank everyone who made a correction, offered a tip, said hello, or found the site to be useful over the years. I'm glad to have had a good long run. I'll still be writing here, so I suppose I'll have to write a bit more often about dinosaurs to make up for it.

Tule Springs Fossil Beds National Monument

I'm sorry about the gap there. I was traveling for work in the Southwest, and was unable to take the time to write anything. Here, though, is a piece about one of the places I saw, albeit briefly: one of the newest National Monuments, Tule Springs Fossil Beds National Monument. This site, north of Las Vegas, was declared in December 2014. It is noted for its abundant Pleistocene fossils, the depth of knowledge concerning its geologic and climatologic history, and historically notable investigations. Having just been established, there are no official National Park Service facilities quite yet.

Looking out across part of the southern end of the monument, facing north-northeast.

Reports of gut contents in herbivorous dinosaurs

I generally avoid writing "nuts and bolts" posts about dinosaurs, because there's a lot of people already doing that who know what they're doing. There is, however, one topic on which I'm uniquely qualified to pontificate. In a previous lifetime I was a fresh-faced graduate student who wrote his thesis on possible gut contents in the "Leonardo" specimen of Brachylophosaurus. As such, I spent a fair amount of time considering the history of possible gut contents in herbivorous dinosaurs, which consists of an exclusive club populated by four hadrosaurs, one ankylosaur, and one sauropod. In retrospect, the Leonardo project was somewhat beyond my powers, but I battled on against overwhelming oddities and came out of it eventually. (For you folks playing along at home, by "herbivorous dinosaurs" I mean more or less classic dinosaurs that aren't theropods. I've got nothing against birds, which include many a herbivorous dinosaur, but they aren't why I got interested in these things, and I don't feel sentimental about them being dinosaurs, because "my" dinosaurs are almost all ornithischians and have all been dead for 66 million years.)

Historic Twin Cities geologic maps and photos

I've been a bit busy lately, so no full post, but here are some historical geologic images and maps of the Twin Cities, 1877–1941. Enjoy!

A map of the surficial geology of Minneapolis and western St. Paul, from Winchell (1877). Note "Finn's Glen" at the end of Summit Avenue, today's Shadow Falls. Also note Bassett's Creek in Minneapolis, once a major waterway but now built over. Some now-defunct quarries and waterfalls are also marked. As far as I know, this and the other maps included here are the oldest published geologic maps for their respective areas.

Small quarries of Platteville stone once dotted the Twin Cities. This is a fairly late example, pictured in Sardeson (1916). Kansan till refers to a now-obsolete system of glacial episodes

Hyoliths and Scenella

One of the aspects of Paleozoic fossils you learn to appreciate is just how many groups had a brief moment in the sun and then disappeared. I'm not just talking about famous things, like trilobites or ammonites (which saved their best for the Mesozoic, of course). You couldn't wade around in an Ordovician sea without crushing or disturbing something that has no living relatives. In fact, given the diminutive size of most of these things, you would probably endanger an entire fauna with each step, so by all means be careful next time you happen to swing by the Ordovician. Today's spotlight shines on two groups that hang around the fringes of Mollusca, and which show up in small numbers in the Ordovician of the Twin Cities: the hyoliths and scenellids.

Cenozoic geology in the National Parks, part III: nonmarine sedimentary formations

And now we come to the last part, and the reason I started this in the first place: National Park Service Cenozoic nonmarine sedimentary rocks and deposits. I had advance knowledge that the theme for this year's National Fossil Day features would be the Cenozoic, so I thought I'd tag along.