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Showing posts from April, 2007

Maximum bite force in Tyrannosaurus rex

I'm on a roll today. Might as well post another.

So obviously, this is a Tyrannosaurus rex. It's so famous I'm afraid I don't really know what else to write about. Oh well, I'll just ramble on about bite forces then.

T. rex has been the focus of many biomechanical studies. Bite force is no exception. However, as much of a celebrity T. rex is, as far as I'm aware, there have only been two studies so far that have attempted to estimate the bite force of T. rex: Erickson et al. (1996) and Meers (2002).

Erickson et al. (1996) had an interesting approach of reproducing bite marks using cast replicas of a T. rex tooth and ramming it into a cow bone. They recorded the forces needed in order to penetrate the bone to different depths. The depths of T. rex bite marks found on a Triceratops ilium was compared to this relationship of puncture depth and forces needed. As a result they found out that a bite force of 6.4 kN were needed in order to to make that bite mark. From th…

Coelophysis bauri

I'm going to start using this blog not only for my technical comments but also to introduce my attempts at life-restorations of theropod dinosaurs. Left is the famous Coelophysis bauri. Coelophysis is one of the best preserved theropods with numerous complete specimens.

One interesting thing about this animals is the supposed evidence of cannibalism. Two specimens have been long considered to have
remains of members of its own species in their thoracic cavities. This view has been recently challenged by Sterling Nesbitt et al. A closer reinspection of the specimens revealed that in one specimen (AMNH FR 7223) the gut contents were actually not even inside the ribcage but underneath it. The second specimen (AMNH FR 7224) on the other hand was shown to actually have bone materials within its thoracic cavity. However, detailed histological study has shown that none of these bones had any diagnostic characters to suggest they were Coelophysis but were more likely to be from a small croc…

Terrestrial-style feeding in Acanthostega

Although the very early tetrapod Acanthostega possesses many adaptations for an aquatic lifestyle, recent work by Molly Markey and Charles Marshall of Harvard University suggests it had a more terrestrial-style feeding. This is a pretty cool piece of work as suture morphologies on the skull roof of a modern fish Polypterus was correlated with suture functions during feeding. Stain gauge measurements in the skull of Polypterus show tension in the anterior and compression in the posterior parts of the skull. The cross-sectional morphology of these sutures seem to be correlated well with the strain patterns. (image left taken from here)

The authors then went on to quantify suture morphology in fossil forms, a sarcopterygian Eusthenopteron, an early tetrapod Acanthostega, and a fully terrestrial Phonerpeton. The cross-sections revealed that while Eusthenopteron showed similar suture morphology to Polypterus, Acanthostega and Phonerpeton did not. Extrapolating the relationship between sutu…

DinoBase Launch

So I am managing an online resource called DinoBase. DinoBase was set up by Mike Benton of University of Bristol about 7 years ago, but had recently undergone a complete make-over. While the old DinoBase used to be literaly tens and hundreds of html pages, the new DinoBase features a dynamic system. It's pretty much a relational database, where all the different categories of information (e.g. genus, location, reference, etc.) are stored in separate tables but link to other tables. This enables data entry to become very quick and easy.

As far as the user is concerned, the information on these individual tables are pulled out and compiled onto a single page, just like any webpage, only that that particular page doesn't exist online as an individual page. So type in a dinosaur genus, species, year of description or author, click on the one you want to view and all the relevant information about that dinosaur will be presented in a single page. This, I think is a very cool system.

Robotic salamander

I know this isn't about dinosaurs but it's more to do with scientific methods in palaeontology. Recently, in the journal Science, there was a paper about a robotic salamander where its gaits are controlled by a spinal cord model. The spinal cord model gives out signals that oscillates the trunk. The team confirmed that the more intense the signal, the higher the frequency of the oscillation gets. This higher frequency oscillation produces a swimming gait similar to that of real salamanders. On top of that, they found that limb oscillation saturates at a lower frequency and the robot switches from walking to swimming.

According to the authors, the main significance of this study is 'to show how a tetrapod locomotion controller can be built on top of a primitive swimming circuit and explain the mechanisms of gait transition, the switch between traveling and standing waves of body undulations, and the coordination between body and limbs'.

This work has been taken up pretty …

Ultrasaurus and Ultrasauros

This is an ancient topic, but I was just thinking about it the other day.

Do you remember that whole thing about Ultrasaurus?

In 1979, James Jensen of Brigham Young University found what he believed to be the largest sauropod ever. The press went mad and widely publicised the dinosaur under the name Ultrasaurus. I remember as a kid that Ultrasaurus (along with Supersaurus) was always depicted as a huge brachiosaur dwarfing even Brachiosaurus.

However, it took another 6 years before Jensen finally published his findings. By then, a Korean palaeontologist, Haang Mook Kim, had already named a sauropod with the name Ultrasaurus because he thought it belonged to the same genus that Jensen had found. But it turned out that Kim's Ultrasaurus was something different, and when Jensen wanted to use Ultrasaurus, his first preference, he couldn't because it was 'preoccupied'. So he instead named his dinosaur Ultrasauros with an 'o'.

Funnily enough, Kim's Ultrasaurus later …