Sunday, February 18, 2018

Identifying invertebrate fossils

Pop quiz! (don't worry, it's not for credit)

Romance *and* brachiopods

Here we have an assortment of fossils, tastefully arranged in a holiday-appropriate setting. They're all the typical local Ordovician stuff, but many Paleozoic shallow marine formations will have a lot of the same general things. What are they, and how can you tell?

Sunday, February 11, 2018

Titanosaurs all the way down

There are a lot of titanosaurs. Over at The Compact Thescelosaurus, there are currently 101 species within Titanosauria, and another 30 non-titanosaurian somphospondyls, which probably include a few things that will be eventually be classified within Titanosauria. (If you're unfamiliar with the term, "somphospondyls" will take some explanation, which I'll get to in a minute; also, "somphospondyl" is a truly unappealing word.) Together they make up a little less than nine percent of the dinosaur chart. Also, as of this weekend, I've removed all of the internal divisions in Titanosauria; it's just titanosaurs all the way down. This is not an admission that all titanosaurs were alike, but rather a recognition that we are still a long way from knowing how they were related to each other.

Sunday, February 4, 2018

The League of Saint Croix

If we can have a "Club Late Ordovician", surely we can have something for those National Park Service units with late Cambrian fossils? Of course it can't just be "Club Late Cambrian". Given that this part of the Cambrian is historically known as the Croixan or St. Croixan (Walcott 1912), it seems fitting to work St. Croix in there somewhere. Therefore, I present the League of Saint Croix. If you're working with a name like "St. Croix", you might as well make it sound like some kind of late Middle Ages/early modern period European military order or alliance.

Sunday, January 28, 2018

Practical guide to St. Croix Valley sedimentary formations

Now that I've seen a fair amount of the Cambrian rocks of St. Croix National Scenic Riverway and the St. Croix Valley, it seems like a good time to set them out as was done for the MNRRA formations. This time around, we'll go to the base of the Cambrian sequence in Minnesota/Wisconsin and work our way up to where the sequence overlaps with the MNRRA rocks. One day I'll have to get into southeastern Minnesota and complete the Paleozoic sequence with the rest of the Ordovician and the Devonian.

As with the MNRRA formations, we're covering a fairly narrow span of time. The Cambrian formations were all deposited between about 500 to 491 million years ago based on biostratigraphic correlations. This includes some unconformities. One other note: I'm working from the Minnesota side of the St. Croix River, and I'm most familiar with the Minnesota names. Mossler (2008) harmonized the stratigraphic nomenclature of Minnesota's Paleozoic rocks with the schemes used in neighboring states, but there is still one difference: the Minnesota Geological Survey uses lithological terms in formation names, while the Wisconsin Geological & Natural History Survey doesn't. The upshot is slightly different names. For example, the units called the Jordan Sandstone and Oneota Dolomite on the Minnesota side of the river are called the Jordan Formation and Oneota Formation on the Wisconsin side. There isn't really a practical difference; the names just look different. In ascending order, the rock units we're most concerned with are the Mount Simon Sandstone, Eau Claire Formation, Wonewoc Sandstone, Tunnel City Group, St. Lawrence Formation, and Jordan Sandstone.

Sunday, January 14, 2018

Diluvicursor

Pride of priority for the first new nonavian dinosaur of 2018 (not counting any of those "available online before 2018 but not in print" guys) goes to Diluvicursor pickeringi, a small ornithopod from Australia. It's the kind of dinosaur that would have been called a hypsilophodont 20 years ago, which means today there's always a chance it ends up outside of Ornithopoda or within Iguanodontia. (Honestly, if your phylogenetic analysis puts all of the old-time hypsilophodonts outside of Ornithopoda, you might as well just abandon the name "Ornithopoda" and go with Iguanodontia for the remainder.)

Sunday, January 7, 2018

Crystal Ball for 2018

For 2018's first post, I once again peer into the mists of futurity and offer dinosaur-centric predictions on the year to come.

Will I once again be called upon to fight a mammoth inside a building? Well, that's always the dream.

Saturday, December 30, 2017

2017 in Review

Aside from the rule of thumb that dinosaur posts attract more hits than non-dinosaur posts, I can't say that I can really predict what people will end up reading. I threw together "When ammonites got bored" at the last minute, knowing I was going on a trip, and it did surprisingly well. "An unfortunate snake" came together in about an hour, unpremeditated (inspired by a conversation with the other Science Museum prep lab volunteers the Tuesday before). I figured readership would be very light due to the holidays, but if I buy the in-house Blogger stats, it's the most-viewed new post since March, and perhaps earlier (for several months in late 2016 and early 2017, there was this weird thing going on where Blogger was counting 30 spurious hits every three hours). Meanwhile, I put a lot of time into "The News in Hadrosaur Dietary Paleobiology" and "Borealopelta", and the reactions were unspectacular compared to other dinosaur posts. Go figure.