Dryosaurus elderae and the revenge of Nanosaurus agilis

It's been a busy few days over at The Compact Thescelosaurus, with new alvarezsaurs, nodosaurs, and dryosaurs. For this post, I'm going to focus on Carpenter and Galton (2018), which not only describes new species Dryosaurus elderae, but also is quite important for previous subject Nanosaurus agilis, and in general ticks off several of my boxes anyway ("hypsilophodonts", Morrison Formation, National Park Service areas, etc.).

Figure 2 from Carpenter and Galton (2018), showing the distribution of bipedal Morrison ornithischians. A keen-eyed observer who's familiar with the Morrison fauna might notice the absence of Drinker nisti and Othnielosaurus consors, and an abundance of Nanosaurus agilis...

Your Friends The Titanosaurs, part 3: Andesaurus, Antarctosaurus, and Argentinosaurus

Plenty of name recognition as far as titanosaurs go in this post of "Your Friends The Titanosaurs", which features Argentinosaurus huinculensis as leading contender for the dinosaur heavyweight crown, Antarctosaurus wichmannianus as one of the most historically important and troublesome titanosaurs, and the somewhat less well-known but supremely steady Andesaurus delgadoi. Three questionable species of Antarctosaurus have been held over for next time.

Lower Decorah trilobites

Following last week with Strophomena, and having figured out what seems to be a good method of photographing small specimens, I thought I'd try my hand at photo-documenting and identifying some trilobites. The sample set is mostly limited to the lower third to lower half of the Decorah Shale of St. Paul, and the most relevant publications for these trilobites are DeMott (1987) and Rice and Hedbloom (1987); Midwest Paleo also has a fine photo-atlas and list. I'm reasonably satisfied that my identifications at the family or subfamily level are accurate. Genus, I'm not so keen on. Species, I didn't even dare; I would be just parroting.

Big Ordovician brachiopods: Strophomena and friends

Starting out in the Ordovician rocks of Minnesota and surrounding states, you run into a few kinds of fossils right away. Depending on the rocks you're looking at, these might include nut-like small brachiopods, fragments of branching bryozoans, ring-like or gear-like crinoid columnals, snail shells, conical horn corals and so on. Among the most noticeable of the common fossils are larger D-shaped shells, up to a few cm across. We've encountered these large shells a few times before in the Platteville and Decorah; they are the shells of brachiopods in the Order Strophomenida, one of the most abundant and diverse groups of brachiopods. To avoid any confusion with Strophomenida, Strophomenoidea, Strophomenidae, etc., and because we're all friends here, we'll just call these large shells "strophs". There are also smaller members of Strophomenida, but we'll leave them be for the present.

A good-sized brachial valve of a stroph in exterior view, embedded in a slab. On the left (A) is the valve viewed from the top, while on the right (B) is the profile, showing how steeply convex it is. Because of mud, this was the only fossil I could see on the slab when I picked it up, but the high profile of the shell clued me in.