Wednesday, November 21, 2007

Cranial skeleton vs postcranial skeleton

Having said what I said in my last post (about a few minutes ago...) I find it rather annoying that there is a huge abundance of literature on the detailed anatomy of the cranial skeleton but less so on the postcranial skeleton. If the dinosaur is known only from postcranial materials then there is a relatively good account of it - of course what else can you write about? Howver, if there is a perfect skeleton preserved, chances are, the description would be skull-heavy. The authors may even state that "the postcranial skeleton would be described elsewhere" but it probably won't be for another decade or so until this publication actually comes out.

I mean, I like cranial skeletons. Skulls are cool! That's what I work on.

But having collected measurements of postcrania from the literature, this popularity of cranial skeleton is really inconvenient...and I don't have the money or time (well for now) to go all over the world and measure these myself. And a lot of the times, it may be "politically" difficult to get access to these specimens...

Spinosaurus aegyptiacus

This is an old picture of Spinosaurus aegyptiacus. I drew this about four years ago using Windows Paint. These were the days before I discovered PhotoShop or Illustrator.

The anatomy may not be exactly correct as I'd only started palaeontology back then - I didn't do any anatomy for my undergrad...

Anyway, this was also about the time I started to get obsessed with spinosaurs. There was something about the skull morphology that really hooked me into them. In more poetic terms, you could say that I fell in love with the beauty of the slender and curvy silhouette of the snout. This was just purely an obsession of mine with no scientific context whatsoever.

Still, I find it quite intriguing that we find rather derived or highly specialised forms such as spinosaurs but no transitional forms. We don't have good fossils that show the evolution of such unique skull morphology...then again, basal tetanuran fossil record is pretty scrappy anyway - for instance Chilantaisaurus tashuikouensis is a giant theropod from China that is supposedly closely related to spinosaurs or maybe even belong to the Spinosauridae but it is only known from partial hindlimbs and a humerus (and maybe a few bits and bobs - I can't remember off the top of my head). So not much of the skull I'm afraid...

Tuesday, November 13, 2007

Albertaceratops nesmoi

This is my attempt at Albertaceratops nesmoi. This is pretty my first attempt at a ceratopsian as well...

The plate-like epidermal structure on the face is purely speculation on my part.

Albertaceratops is yet another one of those interesting centrosaurine with a blade-like nasal 'horn' or ridge, but with postorbital horns that are very large for a centrosaurine.

If ceratopsians locked their horns in intraspecific combat, then Albertaceratops must have had a fairly similar style of combat with Triceratops and other long-horned chasmosaurines - perhaps???