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Showing posts from 2010

Old drawings: Allosaurus, ambush predator

I was flipping through an old sketch book yesterday (only because I was looking for spare large-sized sketch paper for some possible figures in preparation for a manuscript I'm currently working on) and I came across a few old dinosaur drawings that I had completely forgotten about. I present one here.

It's an Allosaurus squatting behind some foliage waiting for the right moment to burst out to attack the group of Stegosaurus. It's even inching forward little by little to get to the perfect position. I wouldn't be surprised if Allosaurus was an ambush predator; lying in wait till the right time to attack, then sprinting up to its prey and delivering a slashing bite to inflict serious wounds to its prey.

With it's relatively small teeth, Allosaurus doesn't fit the bill for an average theropod (even though it is frequently cited as being the quintessential theropod). However, Allosaurus had an incredible gape and very strong neck muscles. So Bakker (1998) suggeste…

How to test if your milk is about to go off

I just 'discovered' this morning that there is a way to test if your milk is about to go off even if it still looks, smells and tastes normal, although you know it's pretty old already. If that's the case and you're worried your milk is about to go off, then here's something you can do to see if it actually is close to going off:

Take some of the milk and microwave it for about 30 seconds. If it's actually pretty old then the milk should curdle; if not, you've got yourself a nice cup of warm milk. Alternatively, you can pour some of the said milk into a cup of hot tea or coffee and see the same effect but you'll end up wasting a perfectly good cup of tea or coffee!

Quick update - two year old Pachyrhinosaurus project

I don't know if anyone remembers this ancient post and this follow-up on my Pachyrhinosaurus reconstruction, but I've just yesterday pulled out my half-finished drawing and started my process of finishing it.  I just realised that my original post was about 2 years ago; it's about time I finished the darned thing.  I've completely abandoned layering by anatomy (e.g. layers of muscle, skins) and reverted to my comfortable method of just fleshing it out the way I like. I've realised it's the only way to get it finished!

I also have to make my post on plotting in R...

R for beginners and intermediate users: reading and manipulating data

I had been preparing a comprehensive tutorial on how to plot in R (The R Project) with different groups differentiated in different colours, but Blogger stupidly erased my post and decided to automatically save my empty draft at that precise moment. Since I cannot reproduce the original post, I decided to break it up into a series of smaller topics.
There are plenty of R resources available in various places but I found that they are frequently one of two extremes; either too basic or too advanced.  I think of myself as an intermediate user (i.e., I can comfortably handle canned packages but want a bit more control than the default settings allow) so the type of info I find are not too helpful. So I thought it would benefit others like me if I summed up some of the simple things I learned over the last year or two.
As a first of such posts, I will deal with reading in and manipulating data.  These may be very simple and basic, but some of the things I wanted to do required a bit more th…

I hate Blogger autosave!

Until now, I quite liked Blogger's auto save feature.  Not any more.  I was hitting Ctrl Z to undo things until for some reason the whole post disappeared, and then at that moment, Blogger decided to auto save.... I lost a whole evening's worth of blogging and I can't remember the phrasing I used which I really liked.


I have been meaning to write about this for the longest time, but things kept getting in my way.  Now, I have the perfect opportunity, as Paolo at Zygoma has coordinated with me to write a post on this very topic.  When Paolo was at the Bristol City Museum, I used to go bother him a lot, and together we'd go through their extensive cat skull collection.  One day, we came across a very interesting tiger skull specimen.  The box kind of said it all; it was labelled 'TIGER' on one end and 'MAN-EATER' on the other.  So we excitedly opened the box and found an isolated skull with no mandible but with a handwritten label.  The label read:

So this tiger was hunting humans for two years (how regularly, no one knows) until someone shot it dead.  Upon examining the skull it was apparent why this tiger was preferentially hunting humans; its canines are heavily worn down.

The canines even look like they could have broken and were subsequently worn down from continued use.  With…

Old drawings: Cars

Next in my line of old drawings is a non-palaeo one.  I always liked drawing cars but was never good at it.  So I'd doodle and try to practice from time to time.  Here, I've got a selection of cars; a Subaru Impreza, some Japanese pick-up truck, a sedan, and another Japanese-style truck with a kind of near-future Sci-Fi anime feel.  Incidentally, Smarty Pants is a product idea I had as a joke (though the technology isn't available to make it happen).

Old drawings: Spinosaur!!!

These are really old, from when I was doing my Masters; one of them is actually dated, 6 June 2004. I was really into spinosaurs back then and I would spend some evenings drawing spinosaurs. One particular evening, instead of drawing life restorations or skull reconstructions, I had decided to draw all the known fossil materials - well, whatever figured material I could find at that time.
The above are my drawings of the preserved cranial and mandibular elements of Baryonyx walkeri and Suchomimus tenerensis that I could see from published figures. I based Baryonyx on a figure in Charig & Milner's chapter in the book Dinosaur Systematics: Approaches and Perspectives (Carpenter & Currie, eds) rather than the description, so the identification of the bones are according to that chapter. By that time I had already had a chance to observe the real Baryonyx material at the NHM, the "jugal" of which is accompanied by an updated label identifying it as an angular.  S…

Old drawings: Allosaurus

Recently, I came across a stash of old drawings that I had completely forgotten about. I'll try and upload them in the next week or two. Some are palaeo, others are not, but still quite interesting nonetheless...
Here is the first. I think it is an Allosaurus head. At least the skull looks like an Allosaurus and it has lacrimal horns like an Allosaurus, so it must be an Allosaurus. Nothing special I guess...

Spinosaurus - biomechanical profile of biting

In a comment to a post on my paper, Andrea Cau suggested I use his reconstruction of Spinosaurus to run my analysis and compare it to the one I used in my paper (the reconstruction from Dal Sasso et al., 2005).
So here is the result. The plot above shows all the mechanical advantages from my 41 taxa as grey dots. The black line is the Spinosaurus from Dal Sasso et al. (2005) while the red line is Andrea's reconstruction. There is an obvious difference, with Andrea's showing higher mechanical advantages overall. However, in the whole scheme of things, the difference is quite small. There isn't a drastic difference in the profile either. So all in all, this is good news, both to me and to those that reconstruct skulls.

New paper: media response

I was originally going to post more on the science in my new paper on theropods, but I thought it would be a good opportunity to present my observations on the media response to my paper (or whatever media coverage there was).
The Proceedings of the Royal Society releases their own press materials before the official online release, the abstract for which, I actually wrote myself (200 words) when I submitted the final corrected version of the manuscript. Following the said press release (but before the online release) I got contacted by two journalists, one for Discovery News and another for Australia's ABC News. I was quite impressed by both journalists' questions; they were very good questions. So I did my best to answer as much as I can in the limited time I had (I was in London visiting the Natural History Museum).
The resulting articles that came out on the day of the online release of the paper were quite good. I was pleasantly surprised. If you haven't already, y…

New paper: jaw biomechanics and the evolution of biting performance in theropod dinosaurs

My new paper on theropod jaw biomechanics was finally published as an early online edition of the Proceedings of the Royal Society B. It became available on Wednesday, 9th June, but I was busy studying cat skulls at the NHM in London and I didn't have much time to comment on it until now. It is a modified version of the study I presented at SVP 2009; although I don't know how many people remember my talk. I made a few revisions to the analyses afterwards (as a response to my reviewers), but the main points are pretty much the same.
This study is pretty much a revamp of my MSc thesis where I compared biting efficiency using a novel numerical method. In my MSc thesis, I looked at how the crushing component of the bite force is affected by jaw margin morphology and how they compare across different theropod taxa. Since it was back in my early days of quantitative comparative analyses, I had no idea (or never occurred to me) how I would go about and compare them numerically (e.…

On biomechanics: simplicity vs complexity

I've been preparing this humongous post on this but decided in the end to postpone it and just put up a short and easy one instead.
I wanted to for some time to voice my opinion regarding biomechanical modelling. And in particular the subject of complexity versus simplicity. Biological systems are frequently very complex, the details of which are often poorly understood. The musculoskeletal system is no exception. I shan't linger on how complex the musculoskeletal system is, but I will comment on the approaches in which we try and model this complexity, or approximate it.
With the advent of affordable computers, it has become expected for biomechanicists to perform high-complexity analyses with many parameters. I'm all for development of sophisticated models and analyses. It helps identify elements of the musculoskeletal system that are otherwise difficult if not impossible to determine. But herein lies the problem; a lot of the complexity, be it the actual values of …

On Republic Commandos: the books not the game

I'm going to comment on Star Wars again, this time on a series of books I recently read; Republic Commando and Imperial Commando by Karen Traviss. This series is supposed to be an official tie-in to the game Republic Commando, which I really liked (although I thought it could be longer; only three stages?!). I was hesitant to read this because I was scared that I would be disappointed by the novels (which I tend to more and more these days) so I had put off reading until Order 66 had just come out. Now being a fan of stormtroopers and clone troopers, I had to read Order 66; that was a requirement for me. But because it was the newest book in a series, I had to first read the other three books, Hard Contact, Triple Zero and True Colours. So I decided to buy these books and started reading.
Hard Contact I found was kind of interesting, not bad at all. Although I found it a bit boring and not at all like the game I was so used to - you know, working as a unit and blasting throug…

On calipers

I'll ramble on about calipers today, just because I like calipers. In my line of business I use calipers very frequently. And not just a normal handy 150mm caliper, but a larger 300mm caliper or an even larger 600mm calliper. So I'll just list my callipers in size order.
150mm glass fibre dial calliper I really like this one, despite the fact that I bought it at a local hardware shop - if it's good enough to refurbish your kitchen or build a bed, then it's good enough for me. So far I've trusted my life with the works of carpenters/engineers so I don't see why I can't trust my measurements using their tools. To begin with, craniometrics are not the most precisely defined measurements and taking these at the precision of 0.01 mm is absurd - rounding to the closest mm is fine, at least it's accurate to the mm or maybe 0.1mm.
Anyway, I digressed. I like this dial calliper because first of all it is very easy to read. Unlike vernier calipers dial callip…

Phylogenetically structured variance in felid bite force II

A while back I attempted to introduce my recent publication. But of course as always I think I got carried away with the phylogenetic aspect of it. So unless I hear otherwise I shall suspend my fascination with phylogenetic signals and here discuss a bit about another interesting aspect of my paper on cat bite forces.
I've discussed bite force a lot in the past so I need not introduce it any more. One idea that is fairly widespread is that bite force is somewhat correlated with ecology and in particular prey preference. This can include dietary categories (hypercarnivorous, omnivorous, etc) or prey size categories (small prey hunter, large prey hunter). Previous studies have indicated that relative bite force (after adjusted for size) seem to have a correlation with prey size categories (Wroe et al., 2005; Christiansen & Wroe, 2007). Other craniodental morphofunctional characters also seem to have some correlation with prey size (Meachen-Samuels & van Valkenburgh, 200…

"Is there a palaeobiologist on board?"

"Is there a doctor on board?"This is one of those lines you hear in movies, dramas, cartoons, etc. but you never expect to hear in real life.But recently I actually heard this announcement on an airplane, though unfortunately I don’t know what the situation was, nor did I have the chance to find out if there really was a doctor on board, if he/she came forwards, and what happened afterwards.So no story there…But I did have a thought:“What if they wanted a PhD instead of an MD? And what kind of emergency situation would require the services of a PhD in palaeobiology?”Perhaps the following:Announcement:Is there a doctor in palaeobiology on board?Palaeobiologist (PB):Why yes, I happen to have a PhD in palaeobiology.Flight attendant:Thank goodness.Please follow me to the cockpit.PB:Certainly.-IN THE COCKPITPB:What seems to be the problem?Pilot:We have a terrorist situation here and we need your expertise.PB:Umm…I don’t think I’m qualified to deal with terrorists…Coilot:Oh, you’r…