Today's quest is to find some information on bone modification, such as scratches and fractures, which are indicative of environment of deposition, presence of other fauna etc... Most of the resources I've found so far are human-centric, with regards to archaeology. It'll be interesting if I find features in Isisfordia duncani and the other Isisford fauna, which have been previously described in archaeological research as "human tool marks"...
Just thought I'd link these amazing light-painted photos of dinosaurs by Darren Pearson. Very festive, actually!
_ (Continued from Part 1)
...Then there's the 'mystery'. The stampede theory has been around for at least 20 years. The only thing new about this documentary is the supposed villain of the piece: Australovenator wintonensis. And throughout the rest of the documentary, it feels like the evidence is being made to fit the suspect.
Using footprint dimensions, ichnologists can calculate hip height and running speed of dinosaurs. These same formulas were used to calculate the running speed and size of the smaller bodied track makers. The documentary team were fine with the conclusions reached: some 30 mm tall (at the hip) dinos running at 14 km/h. When these formulas are applied to the larger footprints, they predict a much larger hip height than the suspect, A. wintonensis! Well not to worry, we'll say that in this case the formula is incorrect, and just assume it was the much shorter A. wintonensis with very large feet. But we'll still use the formula to calculate running speed, and suprise suprise, it was moving very fast, at 17 km/h! So what is the final proof that it was A. wintonensis? Fitting the foot in the footprint.
The computer generated model of the A. wintonensis metatarsals and tarsals are mapped onto a scan of 'its' much larger footprint. Have a look at the pictures below. It appears that the fleshed out model suddenly grows to fit the track! And then the reconstructed life size model (using this blueprint) is created and brought back to Lark Quarry where it *gasp* fits the print! Amazing!
Here's an overlay of the two (kindly provided by the documentary team): note the position of the toes...
_There are other inconsistencies regarding the incorrect measurement of track lengths, the A. wintonensis foot reconstruction being biomechanically incorrect, and the dimensions of the footprint suggesting an ornithopod versus theropod track maker... but I'll leave these to another day, another rant. It's just disappointing that the documentary makers couldn't be happy with evidence of a much larger theropod (if indeed the track maker was a theropod) roaming Lark Quarry, instead of framing poor A. wintonensis!
_Above: images of Australovenator wintonensis pedal reconstruction, from Dinosaur Stampede documentary via ABC, Prospero Productions 2011.
I watched the documentary Dinosaur Stampede on ABC on Tuesday night, and I can't say I'm very impressed with the scientific rigor (or lack thereof) displayed. The documentary focuses on The Dinosaur Stampede National Monument: a dinosaur trackway site containing thousands of dinosaur footprints, at Lark Quarry in central-western Queensland. The original interpretation for this site was that it represented a stampede, with a larger bodied theropod pursuing smaller bodied ornithopods and theropods.
I have to mention my personal bias from the outset: I know the authors who wrote a rebuttal to this stampede story, who claim that the larger bodied track maker was not a theropod, but an ornithopod, perhaps similar to Muttaburrasaurus langdoni. Even so, I think there were some obvious misinterpretations that even an unbiased viewer would have noticed.
The documentary glosses over the first interesting piece of evidence: that the trackway of the larger bodied dinosaur heads in the opposite direction of the smaller bodied dinosaurs. Why would the stampede head toward the supposed threat? Attempts to fit this into the stampede story (here and here) seem awkward and complicated. And it feels like the evidence is being forced into a shoe that doesn't fit (more on that in Part 2). I am a big believer of parsimony: that the simplest explanation is often the most correct. For example, the larger track maker may have passed through before the smaller dinosaurs (heading in the opposite direction) passed through. You can even see some smaller dinosaur footprints inside the larger footprints.
The final CGI movie of the stampede shows the predator chasing the prey, which would have resulted in all tracks heading in the same direction. Why wasn't this problem examined in the documentary?
Trackways at Lark Quarry - note the smaller prints heading to the bottom of the image, and the larger prints heading to the top. Image courtesy of the Queensland Museum "Winton dinosaur trackways - Fact Sheet", 2011.
Keep an eye out tomorrow for Part 2: Australovenator was framed, we need justice!
Well, the front half anyway. In this sketch, you can see from the external basicranium (base of the skull, at the top of the page) to the eighth thoracic vertebrae (approximately half way down the trunk). The left and right scapula, and left humerus, radius and ulna (making up the forearm) are preserved, along with osteoderms and ribs. It's a rough sketch, but while drawing I'm paying close attention to bone surface modification, element orientation and absence of elements to elucidate taphonomic history.
I was able to play with the crocodiles again today! I went to have a look at the anatomy of extant Crocodylus porosus, and ended up staying to help with blood and tissue sample collection from 1.5 yr old crocs for my friend's Honours project. Those little guys will form part of my PhD thesis in about 6 months: as decaying carcasses. Fun times! Never before has an animal been so well utilised!
This film of two women in a canoe watching these amazing starlings in flight is, well, amazing! Breathtaking! And very hypnotic. And they never seem to collide, only merge gently and continue on... the starlings, not the women.
About the author
Dr Caitlin Syme is a palaeontologist who recently finished her PhD at The University of Queensland, studying the taphonomy (preservation state) of fossil non-avian dinosaurs, crocodiles and fish from the Winton Formation, Queensland, Australia. Think forensic science or CSI for fossils, and you're on the right track!
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