Incredulous Teeth, II: The Many Similar Teeth of Zanabazar

Zanabazar junior is a troodontid, named for famed Mongolian Öndör Geγeen Zanabazar (Өндөр Гэгээн Занабазар), an icon who brought Buddhism to the Mongols from the north from China. The name is translated from Mongolian as “known-vigor” and is derived from the Sanskrit Jnana-vajra, which means “thunderbolt of wisdom.” How peculiar that this is a name given to a “brainy” troodontid, animals known for their legginess and apparent adeptness at running down hatchling Maiasaura (and little else). But what is most peculiar about it is not that it is among the largest of troodontids, but that most if not all of its teeth were essentially homodont, or having the same morphology as one another.

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:

Buck Teeth? Wait a Minute….

New news of a new newsworthy theropod dinosaur in the presses. It’s not published in paper yet, although the journal has it available (free) on its website. Because it’s not published (on paper) I will refrain from discussing the taxon (or the paper) virtually at all.

A Little About Interdental Plates

Interdental plates represent another feature of variation in the dental row, and one generally taken for granted by most researchers, and the following illustration represents a crude way to encapsulate some of the variation that occurs in archosaurs. Because interdental plates appear virtually exclusively in crurotarsans and dinosaurs, I focus my attention on the subject to those groups where present.

Tooth Implantation – PiT#2

This is the second “Precision in Terminology” post

Tetrapods generally have only a few ways to affix teeth to their tooth-bearing bones. While most of you readers may be familiar with socket-toothed implantation (thecodonty), the range of dental attachment varies greater than that. Generally, then, there are three types:

A Definition for “Heterodonty”

Teeth in jaws are generally graded by a useage of “heterodonty” versus one of “non-heterodonty.” In some groups, teeth that are actually identical in two spectra (form and size) are termed isodont (literally, “same tooth”) and could reasonably pass for one another without any confusion. The opposite of isodont dentitions has been called “heterodont,” (literally, “different tooth”) but this is used in two ways.

Troodontid Teeth – WP#6

A small selection of troodontid theropod teeth is presented below. Before you get to it, however, note that for among some of these taxa, their identities are a little shaky. This has a lot to do with one of the more persistent “wastebasket” taxa among theropods, Paronychodon lacustris [1]. Among other tooth-based taxa, Paronychodon lacustris and Paronychodon sp. (a general container for a large variety of things, several of which may be unique taxa on their own) includes the morphology of triangular theropod teeth with vertical ridges. Aberrant ridges, carinae, and the apparent absence of denticles in some otherwise theropodan teeth appear on occasion in collections, and most, if not all, of them are referred to the taxon Paronychodon in one of several ways, which I will get into in a different post dedicated to the taxonomy of taxonomy (you heard me).

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!

The Domed and the Tooth(less)

This post will discuss soemthing that a paper has already done in full — however, some conclusions about this paper’s result means that I will re-cover what it did, and make a different argument. That paper is Krause et al. [1]

This is a tale of two taxa, Majungasaurus crenatissimus [2] and Majungatholus atopus [3]. The first was discovered at the Maeverano region on western Madagascar in the 1890′s, while the latter was discovered a bit afterward. Both are likely to be the same animal, as covered in [1], and this argument is not to rehash that or dispute it.