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Showing posts from 2009

On stormtrooper pauldrons from Star Wars

I am going to veer off from my usual (but infrequent) blog posts on palaeontology and blog about another geeky subject.
Star Wars.
I've been a big fan of Star Wars ever since I was a little boy - Return of the Jedi must be the first film I remember seeing at the cinema; my dad took me to see it when I was three but all I remember was being freaked out by Jabba the Hutt and I went through the rest of the film asleep as a sort of a defensive mechanism.
When I was a teenager, I read Kevin J. Anderson's "Jedi Academy Trilogy" then went on to read Timothy Zhan's "Thrawn Trilogy", and from there, I pretty much read every single Star Wars related novel - until I got bored after the story arc reached a time period around 20-25 years since the events of Return of the Jedi (by this point I thought it became pointless to continue reading...).
Anyway, there is one thing that has been bugging me since I was a teenager: when reading through Star Wars materials, I frequen…

SVP 2009 Bristol, and the Romer Prize Session

Despite the complaints that I've heard about the hills and distances from one session to another (come on, it was only a few minutes by foot!), SVP this year was pretty good, in my opinion anyway. I noticed some really good talks with some impressive analytical methods, some really interesting posters, and I also chatted with some intelligent and enthusiastic people.
Of particular interest for me was the Romer Prize Session - not only because I was presenting, but more because Romer Session talks were almost always of high quality research, self-contained and conclusive (unlike some "on-going research", a new locality, or some more scrappy fossils...). Romer talks tend to be more analytically/numerically oriented so there are some stats and numbers to support certain ideas and claims.
There were two talks in particular that I liked, one by my very good friend Tai Kubo (Evolution of limb posture in terrestrial tetrapods inferred from Permian and Triassic trackways), and t…

Updates ... and SVP Romer Prize

I've just noticed that it's been about four months since I posted my last blog entry...It is rather scary how time seems to fly even when you are not necessarily having fun...
Anyway, I thought I might as well advertise this. In the upcoming SVP at Bristol, I shall be giving a talk in the Romer Session:
Myology and functional morphology of biting in avian and non-avian dinosaurs.
It's mostly about non-avian theropods now but I have a couple of birds in there for comparison; I don't know now why I emphasised birds in the title, I could have just said dinosaurs... Perhaps it's because I made much of my myological observations in birds (but also a few crocs).
I shan't write too much about it here, but the work is basically a suped-up version of my Masters thesis from way back, almost six years now... I had to come up with a way to rescue the concept if not the work, after I'd realised I had some fatal flaws in the basic assumptions of the calculations in my Maste…

Phylogenetic constraint

My coauthors and myself recently submitted a manuscript in which we deal a little with phylogenetic constraint. In the process, I came across something interesting and I thought it would be worthwhile to share it here.
Phylogenetic constraint is a concept of evolutionary biology that has had quite a lot of discussion. Mary McKitrick (1993) has a great way of introducing the concept of phylogenetic constraint:
"in some sense, all evolutionary studies implicate phylogenetic constraint, and reviewing the topic is like trying to catch a greased pig."
How eloquently put.
It means everyone loves talking about phylogenetic constraint but it just goes all over the place and there is no real consensus on what phylogenetic constraint is. So despite all this widely held discussion, phylogenetic constraint remains one of the most difficult and least understood subjects, and possibly one that is actually ill defined as well. The problem is, when we talk about phylogenetic constraint, we …

Principal coordinate analysis and the quest for a solution to a non-existent problem

I had an interesting experience yesterday - spent a good few hours on a silly problem. You don't need to know the technicality of the analyses at all, but I'm sure you'll appreciate the humour in this.

I am frequently running principal coordinate (PCo) analyses recently. This is because I am using an interesting application of multiple regressions and PCoA on phylogeny vs phenotypic variables called the phylogenetic eigenvector regression (PVR; Diniz-Filho et al., 1998; Desdevises et al., 2003). In short, you take a phylogenetic tree of a given group of animals (or plants, or whatever your favourite group of organism), reduce the complex topology into manageable columns of numbers (by PCoA), and test these columns with some phenotypic/ecological variable of your choice for any correlations using multiple regression. Sounds pretty easy, and it is, in practice at least. You can code R to do this very efficiently, if you know the R language already.

Anyway, yesterday, I re…

Chimpanzee plans stone attack

I just read an interesting BBC News article. Apparently, a chimpanzee at the Furuvik Zoo in Sweden had been storing hundreds of stones in anticipation of throwing them later at the zoo visitors. Planning ahead is a cognitive behaviour that has not been traditionally associated with nonhuman animals. This behaviour was observed over the last decade and reported in the journal Current Biology.

Previous reports of planning for future states in animals were all experimentally induced and as such one can be skeptic about these behaviours as being potential lab artefacts. However, this zoo chimpanzee showed spontaneous planning that provides support that previous observations made in the lab may not necessarily be artefacts of experiments; at least in great apes. Primary evidence for this is: that the chimpanzee had collected stones or made concrete discs (see below) early in the morning before the zoo was opened to the public but never when the zoo visitors were present; that the chimp…

more on Styracosaurus

Further to my previous post, I've added on some background to my Styracosaurus sketch.

I drew in lots of generic plantlife. I've previously done some research into the Hell Creek flora as a consultant job for Be the Dinosaur. As it turned out, the Hell Creek flora was dominated by angiosperms (about 90%). A lot of that was lobe-leafed plants, and lots of modern families, including the Arecaceae (palm), Zingiberaceae (ginger family), Nelumbonaceae (family including lotus), Rosaceae (rose family), Fagaceae (beech), Urticaceae (nettle family), and Cannabaceae (the family including hops and canabis!). So I drew some random lobe-leaf plants and somethings that look like roses and marijuana...

Of couse, Styracosaurus ain't from the Hell Creek Formation, but who cares.

Styracosaurus albertensis

I sent this in over to the Ceratopsian Gallery at ART Evolved: Life's Time Capsule but I thought I'd repost it here with a bit of my commentary...

I'm sure everyone's seen an image of Styracosaurus albertensis before. It is readily distinguishable from other ceratopsians by the presence of elongated horns on the back of the frill...I don't have much to comment on the dinosaur itself so I will comment on my drawing.

With this one, I didn't bother with skeletal reconstructions. Instead, I reverted to my good ol' habit of drawing from the outline in; I imagine what a live Styracosaurus would look like and draw out the outlines and fill in the details. I guess it's more intuitive and I draw something that I think looks right to me; a very unscientific methodology, I must admit. But this way of drawing is more comfortable for me; it reminds me of when I used to doodle on the back of ads that came with our newspaper.

Anyway, the original is a small sketch on…

ART EVOLVED: Life's Time Capsule - The Ceratopsian Gallery

I have been invited to take part in this cooperative blog on palaeoart, ART EVOLVED: Life's Time Capsule. The current feature is the Ceratopsian Gallery (icon below).



I was late in sending in a piece so I don't have my drawing there yet...[Edit: it's up now]

Olfactory bulb in theropods

Ever since I started having suspicions of the role of olfaction in scavenging behaviours of Tyrannosaurus rex, I have been interested in the olfactory capabilities in predators and how they correlate with their behaviours. So much that I bought a nice book called Predator-prey dynamics: the role of olfaction. However, I shan't write about that book today, even though I quite like it. Instead I shall comment on a paper that became available in Proceedings of the Royal Society B.

I refer to the new study by Darla Zelenitsky and colleagues on the olfactory bulbs in theropod dinosaurs and alligator. Zelenitsky et al. (2009) provide the "first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs". They calculate relative olfactory bulb sizes (olfactory ratio: the size of the olfactory bulb relative to the size of the cerebral hemisphere) in 21 species of theropods (including Archaeopteryx) and 1 species of crocodilian (Alligator mississippiensis) using…

Muscle reconstructions: doing the homework

I know I have been lazy with the postings here, and I really need to finish my Pachyrhinosaurus reconstruction. But I have been faced with a bit of a problem since I've decided to reconstruct this dinosaur one layer at a time, i.e. I wanted to be as accurate in the muscle reconstructions as possible so that the fleshed out version would look realistically three-dimensional even over the skin. Basically, I don't know enough about the postcranial musculature. Previously, I would have just roughly fleshed the whole creature out, from the outside in - basically imagining what a dinosaur would have looked like in life and just sketching it. This way, I didn't really need to be accurate in the myology just as long as the animal looked good enough. However, reconstruction from the skeleton up requires a bit more accuracy on the muscle reconstruction, or at least I would want to be as accurate.

If you have been following my blog for any period of time, you would know by now th…