Incredulous Teeth, I: With Twin Crests

Here begins a new series.

I will be spending some time showcasing the skulls of unusually-dentitioned animals (or showing the peculiar jaws of these animals, specially if they lack teeth). The first of these is Dilophosaurus wetherilli.

Southern Raptors II: Grooves, Cones, and Carinae

When dealing with incompletely preserved or incompletely prepared material, superficial statements are often used to describe a feature so that it can be “assessed” by the readers in some fashion. Take, for example, the following image:

Southern Raptors: Not What They Seem

Unenlagiidae is the name commonly used to envelop a small cadre of southern, Gondwana-only theropods. Recently, some papers have been published that cast new perspectives on these taxa, including a review of the group. Some forthcoming papers even concern the purpose of this blog, but I will not go into them until they are published.

A Cretaceous Parrot?

UCMP 143274, Stidham's Cretaceous "parrot." Schematic views top left and both left and right, drawing in lateral view in top left. From top to bottom, left to right: dorsal view, left lateral view, ventral view, medial (lingual) view from the lateral side. Missing margins are dotted in.

Spinosaurus – a Hint

So last year, I illustrated a series of vertebrae into a novel arrangement, using a variety of cues to inform my decision. Note that this was done in order peek at a topic I’ve been hashing around in regards to potentially presenting in some formal venue, SVP perhaps.

The first step in this analysis was presented in the first post, in which I approached the unusual dorsal neural spines of Spinosaurus aegyptiacus. Many people have approached this specimen, but only one of them has had the opportunity to do so in person: Ernst von Stromer. Sadly, von Stromer is no longer around to share in his understanding of a specimen lost to us through war, but much data persists, including an extraordinarily detailed descriptive paper, one whose model and layout (of description, exhaustive discussion, and comparison occurs well before the author names the form) I wished most modern taxonomists would use. But, I digress.

Better Know a [Aussie] – The Rainbow Serpent of Oz

L. Frank Baum might roll in his grave if I alluded to gay dinosaurs in Oz. Well, insofar as dinosaurs with rainbow-colored bones from Oz (aka, Australia) might be considered “gay.” But that’s just what Kakuru kujani is … a dinosaur based on a tibia that’s been opalized,  transformed into a rainbow-colored mineral, and it’s from Australia. It also just so happens that various indigenous peoples from Australia have legends of a living rainbow, a serpent from Dreamtime, and one of its names (from the Guyani of southern Australia) is “Kakuru.”

My Friend Dave

Meet Dave:

NGMC 91, aka "Dave."

Pubic Orientation — WP#8

One of the more interesting non-dental features of theropod dinosaur evolution is the orientation of the pubis. Historically, it was used to help affirm the transition of the modern bird form from that of particular theropod dinosaurs. Back then, it was Gauthier [1] and Ostrom [2] (and lesser known but nonetheless correct, Barsbold [3]) who tied retroversion of the pubis to birds and dromaeosaurid theropods, but this obscures that some historical perspectives, going back to Thomas Huxley of all people, correctly identified some features of the dinosaurian hip to that of birds. Of course, this was based on the occassional premise that Ornithischia (“bird-hipped ones”) was correctly named in more ways than one.

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:

Tooth Denticles – WP#5

This is a short post; I’d write more about denticles, but I’d want to prepare more material to do so (it’s a detailed subject).

Most carnivorous archosaurs have denticles on their teeth. These are small, nearly microscopic nodules that persist on the carina of teeth (or sometimes off of it). They are serial (i.e., found in a line), and generally occur on the mesial and distal sides of a crown. They occur in non-carnivorous archosaurs, but are less recognized as such. Their shape can be diagnostic, but their presence has allowed systematists to confuse what are dinosaurs and what aren’t, up to including denticulate, blade-shaped crowns that are actually rauisuchian crurotarsans (croc-line archosaurs that include the awesome Postosuchus kirkpatricki and the stranger Effigia okeefeae). What is most odd is that, in the specific cases of some teeth, the identification to group for denticulate teeth can be confused on the morphology of the denticles themselves. Here’s an example:

Variation is not limited here, but it’s instructive. One of these is NOT a theropod dinosaur. Can you guess which is which?