Sunday, April 16, 2017

Mea culpa and Moabosaurus

I apologize for having been light on the whole "Minnesota" and "invertebrates" part of the blog for this year. Having been doing this for a few years now, the low-hanging fruit is picked, and of course the winter is not the best time to be out and about in the rocks, even if "winter" came with quotation marks instead of snow this year. I'm currently on a short trip to Reston, Virginia, to do some work at the USGS, but I thought I'd at least try to put in something relevant for those topics. Then, of course, there’s a sauropod.

I was going to include a photo of fossils in the stone at the Thomas Jefferson Memorial, given it was his birthday on the 13th, but then I realized I'd already done that. Instead, here are some fossils at the nearby George Mason Memorial. Some of the stone used here is fossiliferous, such as in the median area at the entrance, the bench, and the two large inscribed blocks flanking the bench. It is easiest to notice this on the bench, where the stone has been polished by people having a sit-down with the Founding Father.

You can kind of get an idea of it just from seeing the dark areas on the bench.

A tiny nautiloid in cross section surrounded by bits, right of the hat (from George's perspective).

A bryozoan on the top surface of the block on George's right.

For Minnesota rocks in Washington, look no further than the National Museum of the American Indian. The building makes extensive use of Kasota stone (=Oneota Dolomite), resembling an outcrop of southeastern Minnesota transported to Washington. I did look for stromatolites, but came up short.

There's something familiar about this...

No stromatolites yet, although some of the blocks do look suspiciously wormy.


Moabosaurus, previously one of our more senior nomina nuda (nomen nudum = "naked name", or informal name), has left taxonomic limbo and joined the ranks of the published. It had been twiddling its thumbs (a difficult thing to do for a sauropod) since at least 2006, when the name was included in an exposition guidebook. This is a pretty long time as these things go, but on the other hand, compared to this week's star Teleocrater, Moabosaurus was merely inconvenienced. Teleocrater is one of the fabled Tanzanian beasts of Alan Charig's 1956 dissertation (see also Nyasasaurus, a cameo in this post), meaning that it had already been a rumor for fifty years by the time "Moabosaurus" first escaped into the wild.

Genus and species: Moabosaurus utahensis; genus name referring to Moab in Utah, and species name referring to Utah
Citation: Britt, B. B., R. D. Scheetz, M. F. Whiting, and D. R. Wilhite. 2017. Moabosaurus utahensis, n. gen., n. sp., a new sauropod from the Early Cretaceous (Aptian) of North America. Contributions from the Museum of Paleontology, University of Michigan 32(11):189–243.
Stratigraphy and geography: Yellow Cat Member of the Cedar Mountain Formation (Lower Cretaceous), Dalton Wells Quarry west of Arches National Park, Grand County, Utah.
Holotype: Brigham Young University Museum of Paleontology (BYU) 14387, three associated back vertebrae. Lest this sound unimpressive, bear in mind that the Dalton Wells Quarry has yielded approximately 5,500 bones, most of which belong to at least 18 Moabosaurus individuals. Incidentally, Moabosaurus seems to have had a healthy amount of variation.

Although Moabosaurus contributed most of the bones at the quarry, several other forms have been found there as well, including Utahraptor, Nedcolbertia (recently interpreted as an ostrich-mimic), a brachiosaurid tentatively identified as Venenosaurus, the armored dinosaur Gastonia, and the famously unnamed high-spined iguanodont (or tall-spined, whichever you like), along with bits of turtles, choristoderes, crocs, and pterosaurs, and one lonely conifer shoot. Reports of a titanosaur are based on bones now assigned to Moabosaurus. Most bones are incomplete, having been broken by trampling and bored by some kind of insect, probably beetle larvae.

Moabosaurus was long described informally as a camarasaurid, which inevitably it isn't. This is unsurprising, because when you get down to it hardly anything is really a camarasaurid anymore except Camarasaurus, and "camarasaurid", like "hypsilophodont" or "prosauropod", is more useful as a way to evoke a picture in the mind than as a formal classification. Basal macronarian-type things just tend to look like Camarasaurus. In phylogenetic analyses, Moabosaurus generally falls out at the base of Titanosauriformes, a split hair more derived than Camarasaurus. (In other words, if you are a time traveler from, say, 1985, and you are planning to bring back news from the future on dinosaurs, if Euhelopus is a camarasaurid then so is this. Also, you have questionable priorities.) Moabosaurus does have a few tricks up its sleeve, including a possible relationship with the obscure and enigmatic African sauropod Tendaguria and the giant European sauropod Turiasaurus. The latter is interesting because it was initially famous for not being closely related to any known group of sauropods, although if it had been named in 1986 instead of 2006 I wouldn’t have been surprised if it had been called a camarasaurid too (or a cetiosaurid, which is what people used to call a sauropod when they wanted to forget about it). All of this just goes to show, again, that things get complicated down where family trees are splitting. Here's hoping for that iguanodont to be described soon!


Britt, B. B., R. D. Scheetz, M. F. Whiting, and D. R. Wilhite. 2017. Moabosaurus utahensis, n. gen., n. sp., a new sauropod from the Early Cretaceous (Aptian) of North America. Contributions from the Museum of Paleontology, University of Michigan 32(11):189–243.

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