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Showing posts from 2011

Baryonyx walkeri skull

Following on from my previous post, here is another one of my theropod skull line drawings. However, this time, it's a little bit more original than the last one. At least a bit more effort went into it.

This is my 'reconstruction' of the Baryonyx walkeri skull and mandible. I based this on photos of various skull elements (Charig & Milner, 1997; Rayfield et al., 2009) and published reconstructions (Sereno et al., 1998; Rauhut, 2003) all scaled appropriately. I also base this on some personal observations of the specimen at the NHM. The arrangement of the postorbital portion of the skull is largely based on Rauhut (2003) (but ultimately on Irritator) but adjusted so that it fits with the braincase and quadrate. So overall, it looks slightly different from Rauhut's (2003) reconstruction.

My first impressions of Star Wars Episode II: Attack of the Clones

When I first saw posters and merchandising for Star Wars Episode II: Attack of the Clones, I was immediately confused by the weird-looking stormtroopers, which I later found out to be the clone troopers. I was confused by two things: first, I had thought that stormtroopers were a uniquely Imperial thing; and second, I didn't understand why the clone trooper helmets resembled the Mandalorian helmet.

I've been a big Star Wars fan since even before I can remember, but I really got into the Expanded Universe when I was in my early teens, starting with Kevin J Anderson's Jedi Academy Trilogy and going on to Timothy Zahn's Thrawn Trilogy, I was pretty into the Star Wars Universe. I even had an encyclopaedia; Bill Slavicsek's A guide to the Star Wars Universe. And in it was an entry on the Clone Wars, which stated that it was a galactic conflict where the Jedi fought evil forces. And under the entry for Boba Fett it was stated that his armour was that of Mandalorian warri…

Tyrannosaurus rex skull

A while ago, I created some line drawings of several theropods for a talk I was giving. One of those drawings was a Tyrannosaurus rex based on Stan, BHI-3033. It's a simple drawing so I haven't bothered with drawing out all the individual bones, but what I did do was to push the teeth into the sockets so that only the crowns are exposed. It's evident that a lot of the teeth have shot out of the sockets after the animal had died so that much of the roots are exposed. Presumably, this version should be closer to what the tooth row would have been like in life; I don't suppose roots would be exposed too much in life... The result is rather stunning in that the teeth are not as long as you typically see in T. rex skull restorations. And of course, the tips of the teeth form a more uniform and even biting surface. Perhaps I pushed them in too much and maybe the teeth were poking out a bit more, but it shows how much of a difference it makes.

Teaching kids to question things

Not palaeo or art I'm afraid, but kind of along the lines of critical thinking. When I was a kid, I lived in the United States. I also went to elementary (primary) school there. I forgot which grade it was or what class it was in, but one day, my teacher showed a video about the possibility that the Earth could be flat and how we can perceive it to be round; i.e. explanations on why the Earth looks round from outer space when it is really flat (something to do with light bending due to gravity). I was shocked, but apparently, our teacher's aim was to try and engage the kids to question established ideas, which in and of itself is fine. However, to this day, I fail to understand how she thought it would be appropriate to teach kids to question something that is observational, and present an alternative idea that has repeatedly been falsified. Fortunately (and perhaps surprisingly), our class was smart enough, and the video was met with the appropriate scepticism. However, I now…

My Google Sites page

I've set up a new Google Sites page for my research associated stuff, including some basic introductions into my research interests and current projects, but also a section for R tutorials. I've put up my three R tutorials that I've posted here with slight updates. The good thing about a website as opposed to a blog is that pages are easier to navigate (i.e. they don't get lost as time goes by and more and more posts are added as it does in blogs). I'll probably directly post my R tutorials over there from now on and limit my blog here for palaeoart and other palaeo-related posts. In time, I will also add R functions and scripts to my website for anyone wanting to replicate some of the things I do.

Palaeoart: Pachyrhinosaurus

Finally, I have completed my Pachyrhinosaurus! I started it around October of 2008, but with the subsequent job hunt and pushing papers out I hardly had time to make progress with it, and it ended up taking more than two years.

Anyway, here it is.



This is mostly done by referencing some photos given to me by Traumador Tyrannosaur... well, mostly the skull that is; the body is a generic ceratopsian. My fiancée asked me "why do you keep drawing the same dinosaur?" to which I replied "...but they all have different horns". I'm not sure I convinced her but that's essentially centrosaurs in a nutshell; very diverse cranial morphology in an otherwise conservative body plan. I even read somewhere that Greg Paul lumped all centrosaurs into the genus Centrosaurus in his newest book ThePrinceton Field Guide to Dinosaurs (but I haven't read it yet).

When I draw dinosaurs, I usually just draw rough outlines of the animal with very limited skeletal reconstructions (…

Orange Microraptor

Today, I bring you the third instalment of my perching dino/bird series...my orange Microraptor.
I was originally trying to draw Archaeopteryx but realised halfway through that the face was too theropod-looking and decided that I was going to convert it into a Microraptor. Actually, this one is even drawn before my blue Archaeopteryx, so I'm posting things counter-chronologically. But that's not strictly true because I only coloured this sketch in today, so it is technically my newest drawing.

I tried to pose this Microraptor with a half-folded wing; kind of like a bird folding up its wings after either landing on the branch or just extending them out for whatever reason birds extend their wings from time to time. Aside from the obviously interesting point of having tarsal "flight" feathers, Microraptor also is quite interesting in that it has really long primary feathers on the wings proper.

Colouring is as suggested to me by my fiancée, who apparently doesn't li…

Blue Archaeopteryx

This is another rendering of Archaeopteryx, one I'd done before I'd done my red Archaeopteryx. Just like my red Archaeopteryx, I made this guy's head and neck quite fluffy. The colouring is loosely based on a blue jay because I really like blue jays. But also corvids in general; corvids are cool!

...but then in hind sight, it looks a bit too much like a corvid than an Archaeopteryx, I must admit, but this is all in an attempt to make Archaeopteryx look more birdlike rather than a feathered reptile; I think most of the artistic reconstructions out there are too reptilian. I wrote in my red Archaeopteryx post as well but I kind of like the idea that Archaeopteryx and other early birds had more fuzziness about them than widely depicted.

Before anyone says, "How is this an Archaeopteryx, it just looks like a bird?", look at the fluff on the tarsals. And look at the external nares at the tip of the premaxilla. Also, do look at the claws poking out from under the wing (…

Red Archaeopteryx

After a very prolonged hiatus in palaeoart, today I bring you Archaeopteryx, the 'first' bird. I've recently been drawing various interpretations of fossil birds, primarily Archaeopteryx and Confuciusornis, but this rendering is one of my favourites so far.

A red Archaeopteryx perched on a branch.

I've come to notice that Archaeopteryx is most frequently reconstructed with very short feathers along the head and neck. Indeed in the Berlin specimen, there seems to be a general lack of long feathers around the head and neck other than faint striations (Christiansen & Bonde, 2004). Christiansen & Bonde (2004) offer two hypotheses regarding the preservation of contour feathers in Archaeopteryx: 1, the fossil is an accurate representation of plumage in life; and 2, feathers were present but lost during fossilisation. The authors seem to prefer hypothesis 1 and suggest that Archaeopteryx had mixed coverings of large pennaceous feathers and short simple proto-feathers …

R for beginners and intermediate users 3: plotting with colours

For my third post on my R tutorials for beginners and intermediate users, I shall finally touch on the subject matter that prompted me to start these tutorials - plotting with group structures in colour.

If you are familiar with R, then you may have noticed that assigning group structure is not all that straightforward. You can have a dataset that may have a column specifically for group structure such as this:

B0 B1 B2 Family
Acrocanthosaurus 0.308 -0.00329 3.28E-05 Allosauroidea
Allosaurus 0.302 -0.00285 2.04E-05 Allosauroidea
Archaeopteryx 0.142 -0.000871 2.98E-06 Aves
Bambiraptor 0.182 -0.00161 1.10E-05 Dromaeosauridae
Baryonychid 0.189 -0.00238 2.20E-05 Basal_Tetanurae
Carcharodontosaurus 0.369 -0.00502 5.82E-05 Allosauroidea
Carnotaurus 0.312 -0.00324 2.94E-05 Neoceratosauria
Ceratosaurus 0.377 -0.00522 6.07E-05 Neoceratosauria
Citipati 0.278 -0.00119 5.08E-06 Oviraptorosauria
Coelophysi…

R for beginners and intermediate users 2: extracting subsets of data

For my second post on R, I think I will address how to extract subsets of data based on some selection criterion like taxon names. For instance, I have a huge dataset of morphometric variables for at least 36 species of cats (living and fossil). Sometimes I'd like to do some stats on a subset of this dataset, like all the living cats or just on the Panthera lineage species (Panthera and Neofelis). Till recently, I've been doing most of my dataset manipulation in Excel by filtering out certain taxa from the spreadsheet and copy-pasting to a text file, which I read into R. However, you can select subsets of data in R based on taxon names.

In my dataset that I call cat, I have a column labelled Taxa which contains all my taxon names. So typing cat$Taxa would be the way to call up my taxon names.

Let's say I want to extract from my dataset cat just the data for the lion Panthera leo. The associated taxon names in cat$Taxa would be Panthera_leo. So to extract that portion of th…