Dinosaurs of the Morrison Had No Lips … or Did They?

Just a minor post. I wanted to present a portion of a larger project on attempting to illustrate typical dinosaurs (especially ornithischians), and I thought “What better method than that well-sampled and intriguing Morrison Formation and its remarkable diversity?” So I started using a minimalistic stippling technique to draw the “busts” of the Morrison paleofauna, focusing on ornithischians. This has the advantage of allowing me to approach well-studied, well-photographed, and decently accessible taxa from the Morrison Formation. This runs into a small problem, that of the composition of the Morrison “fauna,” which is in fact comprised of several temporal (and apparently regional) faunae. To simplify things, I am ignoring all of that.

The Demon of the Chinle

Very rarely do you get to just shove your hand deep into the Mythology Pool and pull out a name like Daemonosaurus.

When Flat-Head Met Dome-y

One of the most interesting aspects of ornithischian phylogeny has been (alongside whether heterodontosaurs are ornithopods or whatever) is the nature of many pachycephalosaur taxa. Recently, Schott et al. (2003) have done some great detective work in nailing down what they expect to be a firm argument for expected ontogeny in pachycephalosaurs.

On Ceratops

Three things to note here:

1. Ceratops montanus is not complete, and is based on incomplete cranial remains that are considered unusable for further taxonomic purposes. It is, in short, a nomen dubium.

2. The word ceratops is a Latinized compound of a set of two Greek words. This is more complicated than it sounds. It impacts everything from how the word is pronounced to how it is combined with other words, to how it is expressed in translation, etc.

3. Not all “ceratops” taxa are dinosaurs. There is a marked trend in taxonomy for some groups to use a prefix, infix, or suffix of a certain form for many taxa, and in dinosaurs this is no different: you get -titan for some sauropods, -pelta for some ankylosaurs, -raptor for small, predatory theropods, and of course, -ceratops for ceratopsians.

Leaellynasaura and Caudal Length in Ornithischians

Recent attention as risen in regards to a brief abstract submitted at the 69th Annual Meeting of the Society of Vertebrate Paleontology, held in September of 2009 in Bristol, England. There, William Matthew Herne presented a preliminary report of material previously referred to one of the classical austral ornithischians, Leaellynasaura amicagraphica [1], which is available here. Therein, Herne describes this specimen has having a tail of over 70 caudal vertebrae (unheard of before save in hadrosaurs), and comprising around 75% of the total body length. A fantastically long tail.

Tooth Denticles — WP#5 (Update)

A few weeks ago, I posted this image:

And I asked this question:

“One of these is NOT a theropod dinosaur. Can you guess which is which?”

After a few weeks, I’m closing this gripping debate:

Sabre-Toothed Dinosaurs

And not one of them is a theropod. Oh, you’re thinking of Incisivosaurus gauthieri? It’s clearly a bunny-toothed dinosaur.

What follows is a discussion on one of my favorite topics: The dentition of Goyocephale lattimorei.

Anticipation

I am fairly interested in the work that is presented in New Perspectives on Horned Dinosaurs [1], a volume of data that should be useful to someone like me. More, I am interested in putting forward some posts on ceratopsians (or rather, marginocephalians), the most interesting group of ornithischians I know of. A recent piece by Hungarian paleontologist Attila Ősi (and friends) describes a new “bagaceratopsid,” Ajkaceratops kozmai [2] – a basal coronosaurian ceratopsian with some interesting oral anatomy. It may even be a dwarf taxon, much like the famed dinosaurs of Haţeg, Romania.

This is all interesting stuff once you get into ceratopsian oral processing, the restriction to orthal and limited propalinal jaw movement, and the peculiar anatomy of the predentary and rostral bones along with the occasional retention of premaxillary teeth. Moreover, the extreme akinetism in even the most basal ceratopsians is of extreme interest, and you should expect to hear from me about it.

Much thanks to Tom Holtz for helping me with the Ősi paper!