New Wroe paper on the thylacine

[Surroundx]

While looking for citations to add to my thylacine bibliography I came across a library catalogue listing with a new paper by Stephen Wroe in it. I looked up Google Scholar but could only find the citation. Does anybody have access to this paper?

Abstract:

"Aboriginal land use patterns, climate change and competition with dingoes have been linked to the Tasmanian tiger's extinction on the continent's mainland. For this, our research team from the University of NSW has recently analysed the mechanical performance of the Tasmanian tiger's skull relative to two living marsupial predators - the Tasmanian devil and spotted-tailed quoll.\n The seemingly disproportionate and even stumpy legs of the Tasmanian tiger do not appear to be suitable to long distance pursuit. New Beginnings What role does research have in shaping our perception of the species? Since the extinction of the Tasmanian tiger there has been a new wave of understanding of their behaviour."

Attard, Marie and Wroe, Stephen. (2012). The Thylacine Myth-A new study of the biomechanics of the Tasmanian tiger's skull debunks the hysteria behind the campaign that led to its extinction. Australasian Science 33(5): 19. [incomplete citation]

[Deleted]

"Unsuitable for long pursuit"
Every thing I have heard about the thylacine is that it is a plodder, Once it got on a scent trail nothing would shake it off until it caught up with the exhausted prey.
Usually roos and wallabies.
BC

[youcantry]

"do not appear to be suitable to long distance pursuit"

"Do not appear".

Apparently humans are designed for running. Deer, not so much. So apparently when humans chase deer, humans cool down by perspiring. The breeze as you run keeps you cool. But deer, on the other hand, need to pant to cool down. (I mean, we all cool down by both perspiration and panting, but for humans, perspiration plays the major part, and for deer it's panting).

Problem is, a deer can't pant if it's running. You don't have to be fast - you just have to keep the deer on the move. Apparently if you can chase one for about 20 minutes, it'll just collapse in a heap on the ground from heat exhaustion. You then just walk up and kill or capture it.

Now... to the question "What role does research have in shaping our perception of the species?" (which I think is an excellent one - I mean, they appear to be proposing debunking every single witness that claimed the thylacine pursued its prey relentlessly on the grounds of looking at the tiger's "stumpy legs") I ask: researchers: can you tell me whether the thylacine's primary heat exchange is through perspiration over panting? If so, then tell me whether pademelons and other macropods primarily exchange heat through panting. If so, then who cares if it has stumpy legs - a 20 minute slow-mo pursuit would be enough to capture its prey and be consistent with the eyewitness accounts.

www.chrismcdougall.com/book.html

"For centuries they have practiced techniques that allow them to run hundreds of miles without rest and chase down anything from a deer to an Olympic marathoner while enjoying every mile of it."

and:

www.lehigh.edu/~dmd1/art.html

"Tarahumara running is based on endurance not speed. This fact is exemplified by their hunting practices. In order to catch such wild animals as deer, wild turkeys, and rabbits, the Tarahumara simply chase after the animal until the animal drops from exhaustion. Their hunting practices are widely known in Mexico and ranchers have been known to hire the indians to chase down wild horses ." (emphasis mine)

[harry hunter]

kangaroos lick their forearms to cool down

thylas pant while resting during a hunt

the mate takes over the chase until the resting thyla has recovered enough to continue

these days fences block an easy escape for young kangas which cannot leap over them

so the defenceless youngster is captured and dispatched easily and very quickly with a jaw clamping down on the back of its neck and a shake or two to break the neck

the usual pursuit distance is about 1 - 2 km so the chosen prey can be cut out from the mob and driven into fence

the male generally makes the kill after the rest of his family has herded the prey into the fence

[molloch]

The movement economics of a macropod mean that it basically can not be run down by a quadruped through sustained pursuit alone. If thylacines evolved to run down macropods, they would be built far differently, or they would hunt in packs, like dogs.

Here is the link to the article:

www.australasianscience.com.au/article/issue-june-2012/thylacine-myth.html

but you need a subscription. This is more of a popular article than a peer reviewed one, by the looks of it. None of the uni's I have access to seem to have it.

[Surroundx]

I don't know what I'm talking about here, but I believe that the tigers' stripes are generally believed to have evolved for camouflage. So it seems to me that perhaps the thylacine also stalked its prey, and perhaps scavenged like the TD when the opportunity arose.

[Thylacoleo Gal]

Jul 1, 2012 11:52:32 GMT 10 Surroundx said:

While looking for citations to add to my thylacine bibliography I came across a library catalogue listing with a new paper by Stephen Wroe in it. I looked up Google Scholar but could only find the citation. Does anybody have access to this paper?

Attard, Marie and Wroe, Stephen. (2012). The Thylacine Myth-A new study of the biomechanics of the Tasmanian tiger's skull debunks the hysteria behind the campaign that led to its extinction. Australasian Science 33(5): 19.

I should(?) be able to lay hands on a copy next week. But if anyone else can find one sooner ..

[Thylacoleo Gal]

Jul 1, 2012 22:36:29 GMT 10 molloch said:

The movement economics of a macropod mean that it basically can not be run down by a quadruped through sustained pursuit alone. If thylacines evolved to run down macropods, they would be built far differently, or they would hunt in packs, like dogs.

We've paced kangaroos at ~40km/hr over a sustained distance, and something that's puzzled me as a result is this. Evolution produces designs that are "good enough". If you're fast enough to outrun a lion, that's good enough: you get to pass on your genes to the next generation. Question is, why are kangaroos able to run - or rather, bound - so fast over long distances when there's nothing in the Aussie landscape today that can chase them at those speeds? Apart from motor cars, that is.

[molloch]

I think it has probably got something to do with being able to move long distances when drought hits rather than predator avoidance. I have no research to back this up, so I am just throwing the idea out there. They are not actually that capable of fast, sustained saltation, but they are certainly very economical when travelling within a certain speed range range. Evolution will favour those kangaroos that are able to hop a little bit further to find decent food and water. Reduction in panting would also conserve fluids.

[Surroundx]

Jul 2, 2012 21:28:36 GMT 10 Thylacoleo Gal said:

We've paced kangaroos at ~40km/hr over a sustained distance, and something that's puzzled me as a result is this. Evolution produces designs that are "good enough". If you're fast enough to outrun a lion, that's good enough: you get to pass on your genes to the next generation. Question is, why are kangaroos able to run - or rather, bound - so fast over long distances when there's nothing in the Aussie landscape today that can chase them at those speeds? Apart from motor cars, that is.

Perhaps their hopping ability is a remnant of the Late Pleistocene (or earlier) environment in which the traits (as opposed to the macropods themselves) evolved. They were predated by carnivorous marsupials which produced a sufficient evolutionary pressure to force them to adapt by becoming ever more efficient and/or fast to escape being eaten.

Evolution has no foresight, and so even though there may no longer be a pressure on macropods to maintain their superior bounding ability (and it may use up more energy than the traits are worth), their efficiency at bounding will only reduce to "good enough" over time (it's more complicated than that). But that is of course assuming that no current pressure is forcing them to maintain their efficiency. Whereas molloch pointed out one clear possible advantage to the most efficient individuals over those less efficient. And even without any hard data to back it up, given the aridity of much of the Australian landscape and the scarcity of water/suitable vegetation it seems to me to be a real possibility.

[Thylacoleo Gal]

Yes, that's what I was getting at. In order for evolution to equip macropods with extreme fleetness of foot, there must have been predation pressure to drive the selection process. But what sort of predator in prehistoric Sahul could run that fast? Not Thylacines and not Thylacoleo. What about Steve Wroe's terror bird?

* When I said "sustained distance", I was talking about maybe 200 - 300 metres at greater than 35km/hr. The 'roos were drawing away even at that speed but we had to break off because the rough track would have smashed something under the car. The take-home lesson was that 'roos, in this case Western Greys, are pretty damn fast when they need to be. Cheetah speed, really. But what selective pressure gave them that extraordinary ability?

[Deleted]

Aaahhh B**** it why should I bother to stick my bib in.
I've only lived with the B things for a lifetime, so what would I know.
BC

[Surroundx]

Jul 3, 2012 8:59:52 GMT 10 Thylacoleo Gal said:

Yes, that's what I was getting at. In order for evolution to equip macropods with extreme fleetness of foot, there must have been predation pressure to drive the selection process. But what sort of predator in prehistoric Sahul could run that fast? Not Thylacines and not Thylacoleo. What about Steve Wroe's terror bird?

* When I said "sustained distance", I was talking about maybe 200 - 300 metres at greater than 35km/hr. The 'roos were drawing away even at that speed but we had to break off because the rough track would have smashed something under the car. The take-home lesson was that 'roos, in this case Western Greys, are pretty damn fast when they need to be. Cheetah speed, really. But what selective pressure gave them that extraordinary ability?

Perhaps we need to invoke an unknown Late Pleistocene carnivorous taxa to explain the fleetness of foot of Western Grey kangaroos (and other macropod taxa)? ;D Given the scant remains of some of the MF, some known only from fragmentary remains, the existence of an as yet unknown carnivorous species doesn't seem that farfetched, especially given the fact that predators have lower population densities than their prey.

I was wondering whether megalania could be responsible? I don't know very much about varanids but I know that perenties can move very fast up a tree when danger hits. But I'm not sure how long they could sustain that speed for, and even less so whether megalania could.

Then again, perhaps we are missing something quite obvious. Perhaps their fleetness is just an exaptation or a coincidence? I'm getting quite excited thinking about his mystery now the more I think about it.

[Deleted]

Well there are plenty of thylacinids to choose from, I think it's up around 13 species known from the Thylacinidae in the fossil record.
T potens could be big and dangerous enough to give a roo a run for it's money?