“You Keep Using That Word”

Behold another rant on nomenclature, posted on the Dinosaur Mailing List recently. I am slightly modifying it for consumption here.

I Cannot Compel to Reason: Triceratops, We Done It Again

Earlier this year, Andy Farke took the opportunity of  a remodel to assess the skull of that classic of classic dinosaurs, Nedoceratops hatcheri. Formally named by Richard Swan Lull (completing a monograph that first OC Marsh had begun but uncompleted by hid death, and then resumed by John Bell Hatcher until his death), he presumed it may have been a pathological specimen, probably Triceratops (one of its species, many of which abounded at the time), owning to large irregular rather than concise fenestrae in the parietals and one of the squamosals; but he relented on the idea of its apparently unique features and coined the name Diceratops hatcheri. The name would be later found to be ironic.

New Domes, New Interpretations

Thanks to Bob Sullivan, many of his co-authored publications from the New Mexico Museum of Natural History and Science (NMNHS) Bulletin are now available online (which you can find here). I talked about one of them, naming new oviraptorosaurs Ojoraptorsaurus boerei and Epichirostenotes curriei (Sullivan, Jasinski & van Tomme, 2011). The new papers recently made available include the descriptions of two new pachycephalosaurs, and comments on others. First, a frontoparietal from the Bayn Shire Formation (= “Baynshire Suite(Formation)”) of southern Mongolia is named Amtocephale gobiensis (Watabe, Tsogtbaatar & Sullivan, 2011). Second, a new species of Stegoceras, Stegoceras novomexicanum, is named from several specimens from the Fruitland and Kirtland Formations in the San Juan Basin of New Mexico (USA) (Jasinski & Sullivan, 2011).

Sabretooths Spread Thick and Thin

Some time back (about a year ago, in fact), I wrote about the hypothesis where Heterodontosaurus tucki, a small ornithischian from the Early Jurassic of southern Africa, might actually have been a basal marginocephalian, joining the ranks of blatant look-a-likes like Goyocephale lattimorei and Yinlong downsi. This hypothesis is covered in some level there, so I won’t go into it that much here. But as the title of this post might suggest, there was a rebuttal.

O Crest-less One

My brief forays into ornithischians is usually relegated to those heterodont taxa that are basal ornithopods and their ancestors (but not descendant thyreophorans, ceratopsians or pachycephalosaurs) because of the wonderful arrangement and oddity of their teeth. Once you get past them and into ankylosaurs, stegosaurs, ceratopsids, and iguanodontoids, things get a little more boring when it comes to variation. These taxa become essentially homodont and even isodont (their teeth remain roughly the same size mesiodistally). While understanding tooth variation includes understanding its restriction to the morphology of elongated and supernumerary tooth rows, as in hadrosaurs and ceratopsians (acquired convergently), I am more interested in understanding how they got there.

That Was Fun….

Apparently my Google-fu is good.

Systematic Originalism

On occasion, systematists feel the need to revise the taxonomy of various species, placing species into new genera, or lumping them in with other species in earlier-named genera. This is generally supported by phylogenetic analyses, but sometimes it involves an argument of differentiation based on physical differences, or mere opinion on the basis of particularly “important” features (generally autapomorphies). This can have several results, but the most common is that a systematist will erect a new genus for a “special” species formerly placed in another genus. Ignoring the question of what a genus is, we wonder what the answer to the question “What is the value of a generic assignment?”