Compact Thescelosaurus Year Four

It's time for the annual update to The Compact Thescelosaurus, now entering its fifth year. This time, ichthyosaurs join the group, which is really stretching it for me, but hopefully it's not entirely in vain. Ichthyosaurs fared a bit better than plesiosaurs in that *only* 91 of the 224 species (40.6%) included are of questionable validity, rather than 173 of 318 (54.4%). (Only.) My go-to work was McGowan and Motani 2003 on Ichthyopterygia (Handbook of Paleoherpetology 8), just to figure out what was there. Ichthyosaurus itself, like Plesiosaurus, accumulated an awe-inspiring retinue of species over the years, but it's not alone. A couple of areas of ichthyosaur taxonomy are pretty volatile at the moment as massively specious genera are re-evaluated, so expect revision. (Also expect the usual formatting bugs and obvious corrections that come with a new sheet.)

Sure, like you don't know what an ichthyosaur looks like. This was found at Wikimedia Commons, but originally came from a short item by William Diller Matthew in the American Museum Journal for January 1908.

The classification diagrams have also been updated. There are a number of ichthyosaur families named for one genus, which I have omitted because I've never seen the point of monogeneric families. As with the sauropterygian tabs, you might notice a lot of "unknowns" in the Formation column, which generally is due to one (or both) of two things: dubious species named some time ago without the benefit of a formation name, and with no follow-up; or cases where the biostratigraphic position was given, but no formal formation name.

Now, the review. Beginning with the date of our last review on October 14, 2018, I've entered 143 items on the Updates sheet. These included 62 new species, 6 sinkings of species that had full row treatment (and a seventh, Pterodactylus occidentalis, that was only a note in "leftover Pteranodon bits"), 6 removed species, 4 reinstatements, 1 transfer of a species to a new genus (Amphicoelias fragillimus to Maraapunisaurus), and 1 addition of an overlooked species (misleading named dubious plesiosaur "Ichthyosaurus" nasimovii).

In temporal terms, the 62 new species are biased to the Cretaceous, as is usual, but not as much as the absolute numbers might suggest; compared to previous years, the proportions are not all that different. There were 2 Middle Triassic species, 6 Late Triassic, 3 Early Jurassic, 2 Middle Jurassic, 7 Late Jurassic, 3 Cretaceous of uncertain position, 17 Early Cretaceous, and 22 Late Cretaceous. Geographically, Asia, South America, and Europe produced almost equal contributions (16 for Asia versus 14 for the other two), with North America following at 8, and 5 from Africa, 4 from Australia, and 1 from Antarctica. At the national level, the spread was flatter, with no one country hitting double digits. We have the same top three from previous years (China at 8, the United States at 7, and Argentina at 6), with Brazil tied for third place at 6. They were followed by Australia, Mongolia, and Spain with 4 each, then Germany and Thailand with 3 (a great year for Thailand; all theropods), four nations tied with 2 (Colombia, Italy, Morocco, and Tanzania), and eight more with 1 (Canada, France, Japan, Portugal, Russia, South Africa, Switzerland, and the United Kingdom). Taxonomically, we got:

1 new choristodere species:
Coerulodraco jurassicus

1 new placodont species:
Cyamodus orientalis

2 new basal sauropterygian species:
Nothosaurus cristatus
Panzhousaurus rotundirostris

3 new plesiosaur species:
Leivanectes bernardoi
Lindwurmia thiuda
Sachicasaurus vitae
This covers a wide range of kinds of plesiosaurs, with elasmosaurids (L. bernardoi), pliosaurids (S. vitae), and basal plesiosaurs (L. thiuda). Geographically and stratigraphically, it's more limited, because both L. bernardoi and S. vitae are from the Lower Cretaceous Paja Formation of Colombia.

9 new pterosaur species:
Coloborhynchus fluviferox
Cryodrakon boreas
Ferrodraco lentoni
Iberodactylus andreui
Keresdrakon vilsoni
Klobiodon rochei
Mistralazhdarcho maggii
Nurhachius luei
Seazzadactylus venieri
It's a bit odd that no dinosaurs should have been named from Canada over this twelve month period. Instead, Cryodrakon boreas is there to represent it. Azhdarchoids and anhanguerians did well, represented by 6 of the 9 species, and a seventh (Nurhachius luei) is just outside of Anhangueria. The two clear exceptions are basal pterosaur Seazzadactylus venieri and rhamphorhynchid Klobiodon rochei.

1 new dinosauromorph species:
Kwanasaurus williamparkeri, a silesaurid

19 new theropod (non-bird) species:
Ambopteryx longibranchium
Archaeopteryx albersdoerferi
Gobiraptor minutus
Hesperornithoides miessleri
Imperobator antarcticus
Lingyuanosaurus sihedangensis
Moros intrepidus
Nhandumirim waldsangae
Notatesseraeraptor frickensis
Phuwiangovenator yaemniyomi
Saltriovenator zanellai
Shishugounykus inexpectus
Siamraptor suwati
Suskityrannus hazelae
Thanos simonattoi
Vallibonaventrix cani
Vayuraptor nongualamphuensis
Vespersaurus paranaensis
Xingtianosaurus ganqi
Almost every major group of non-avian theropods came out with a new species or two since last October. Conversely, this means that no particular group dominated the year, either. The most unusual in terms of stratigraphy was the troodontid Hesperornithoides miessleri from the Morrison Formation, although to be fair its existence was not unprecedented based on current knowledge of theropod evolution, and the troodont-like tooth taxon Koparion is also known from the Morrison. (Also, the community had known about it for more than a decade before its official description, which lessened the surprise a bit.)

2 new basal sauropodomorph species:
Macrocollum itaquii
Ngwevu intloko

9 new sauropod species:
Baalsaurus mansillai
Bajadasaurus pronuspinax
Itapeuasaurus cajapioensis
Kaijutitan maui
Lavocatisaurus agrioensis
Mnyamawamtuka moyowamkia
Oceanotitan dantasi
Volgatitan simbirkiensis
Wamwerecaudia keranjei
Most of these clumped into two groups: titanosaurs (B. mansillai, K. maui, M. moyowamkia, and V. simbirkiensis), and dicraeosaurids and rebbachisaurids (B. pronuspinax, I. cajapioensis, and L. agrioensis). The other two were a somphospondyl (O. dantasi) and a "mamenchisaurid" (W. keranjei) (nothing against Mamenchisauridae, but there are some serious and as-yet unaddressed issues with Mamenchisaurus).

2 new thyreophoran species:
Adratiklit boulahfa
Mongolostegos exspectabilis
Both of these are stegosaurs, which is a miracle on par with the Minnesota Twins defeating the New York Yankees in the playoffs.

2 new ceratopsian species
Crittendenceratops kryzanowskii
Psittacosaurus amitabha
You get one ceratopsid and one basal ceratopsian, and no points for guessing which is which.

11 new ornithopod species:
Adynomosaurus arcanus
Aquilarhinus palimentus
Convolosaurus marri
Fostoria dhimbangunmal
Galleonosaurus dorisae
Gobihadros mongoliensis
Kamuysaurus japonicus
Mahuidacursor lipanglef
Pareisactus evrostos
Sektensaurus sanjuanboscoi
Weewarrasaurus pobeni
These days, translating between various authors' conceptions of the base of Ornithopoda requires care and attention (and I still say if you end up with Hypsilophodon outside of Cerapoda, just dump the name Ornithopoda and call the remainder Iguanodontia. Yippee.). At any rate, new species that might have been called "hypsilophodonts" at one time include C. marri, F. dhimbangunmal, G. dorisae, M. lipanglef, P. evrostos, S. sanjuanboscoi, and W. pobeni (three of which are from Australia, which makes a great twelve months' output for this year's SVP host). The other four (A. arcanus, A. palimentus, G. mongoliensis, and K. japonicus) are all hadrosaurids, meaning the "middle" of Ornithopoda (the traditional iguanodonts) has not made an appearance.

4 reinstatements, all dinosaurs:
Breviceratops kozlowskii
Psittacosaurus lujiatunensis
Psittacosaurus major
Sigilmassasaurus brevicollis

6 sinkings of species with full row entries:
Chuxiongosaurus lufengensis into Jingshanosaurus xinwaensis
Longchengpterus zhaoi into Nurhachius ignacriobritoi
Magnirostris dodsoni into Bagaceratops rozhdestvenskyi
Pseudolagosuchus major into Lewisuchus admixtus
Rhomaleosaurus propinquus into R. zetlandicus
Teyuwasu barbarenai into Staurikosaurus pricei

Finally, 6 taxa were removed altogether:
Balaur bondoc (more birdy than permitted by house rules)
Elopteryx nopcsai (more birdy than permitted by house rules)
Eotomistoma multidentata (restricted to the non-choristoderan material)
Iserosaurus littoralis (not actually a plesiosaur)
Wyleyia valdensis (more birdy than permitted by house rules)
Zhongornis haoae (more birdy than permitted by house rules)

Also, anybody ever see one of these? I saw it in a Platteville block on the Winchell Trail. It's like some kind of thin membranous thing with mineralized veins where it crinkled. I'd like to think it's all a secondary mineralization of some sort, but I can't shake the feeling it's some kind of fossil. I've never seen anything like it. Maybe a chunk of crumpled and somewhat mineralogically altered carapace from a large arthropod? [Update, 2019/10/18: I'm beginning to suspect this may be akin to a trace fossil known as Palaeosynapta (sometimes incorrectly spelled Paleosynapta) flaccida, originally described as a possible sea cucumber by Malcolm Weiss in 1954. Both have wrinkled surfaces with irregular networks of crystals, and are comparable in general shape and size (see the object included as 3a in Weiss's Plate 41). Citation is Weiss, M. P. 1954. Notes on some Middle Ordovician fossils from Minnesota. Journal of Paleontology 28(4):427–429.]