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.

Cenozoic geology in the National Parks, part II: igneous

Quite a number of NPS units record some form of Cenozoic igneous activity, from the obvious (active volcanoes) to the subtle (rock formations that are composed of volcanic debris, or ancient lake deposits that were laid down after a lava flow blocked a river). Restricting the category to just those with Cenozoic igneous rocks still nets quite a few. I decided to go with just those where the igneous rocks are responsible for a headline attraction, or make up a significant part of the bedrock. I've got both a map and a spreadsheet of igneous activity in geologic time, and as you go through you may notice a few patterns. First, a lot of the featured parks have fairly recent activity, roughly Miocene to the present, a span of about 23 million years. Part of this is a natural bias of erosion (younger, less-eroded igneous features are more impressive than old, worn-down features), and part of this is due to the timing of the eruptions themselves. Volcanism on the Rio Grande Rift of New Mexico began shortly before 23 Ma, Great Basin volcanism began around the same time, the Yellowstone Hotspot trail has only been traced back around 16 million years, and the volcanoes of the Hawaii parks only poked out from the ocean during the Pleistocene. Another feature is location. There is a nice arc through southern Alaska, and clusters in northern California–southern Oregon, around the Great Basin–Mojave Desert, in New Mexico, and eastern Idaho–northwestern Wyoming, which correspond to centers of igneous activity.

Cenozoic geology in the National Parks, part I

I thought it might be interesting to briefly highlight some National Park Service units in terms of geology, and started working in the Cenozoic Era (66 million years ago to the present; you can get a fresh new geologic time scale here). The draft became quite long, so I chopped out the igneous and terrestrial sedimentary parts for later and collected the smaller headings. Many of the following parks have been detailed in NPS Geologic Resource Division publications and maps, which can be found here.

The Urban Paleontologist

Winter in the U.S. is not the best time for looking for fossils. It's cold, the days are short, and a significant portion of the ground is covered with snow and ice. There are, however, other places to see fossils than in the field, some of which you may pass every day. Many buildings include fossil-bearing stone, representing sites around the world.