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Re: Sauropod necks 2 ( was Re: Dino reputation 'is exaggerated')



Taking the chance to expand--

An analog more apt than crampons would be
tree-climbers such as are (or were) used by
lumberjacks, telephone repairmen and treesurgeons. A
lumberjack wearing "treehooks" has a single spike on
each foot. When he is climbing up a treetrunk, the
body's weight (minus that supported by the hands) is
supported by one spike as the other is moved up and
then driven into the tree. If the spike is too small,
it will not have enough "traction" to support the
climber's weight, precipitating a painful (or even
fatal) event known as "skinning out"; if it is too
large, it becomes difficult to penetrate the trunk,
leading to the same result. Note that almost all
propulsive forces are generated by the legs, _not_ the
hands which are mainly used for stabilization.

Small spikes are used for climbing de-barked poles,
and larger spikes are used for trees. The largest size
commercially available are for climbing thick-barked
and/or dead trees. 

As I can attest, you can also skin out when
transmitting force to the tree with your hands, (or,
logically, teeth), while both spikes are set in the
tree. 

Which begs the question--
Are "sickle claws" in the various Dromaeosauridae
appropriately scaled/engineered for transmitting
propulsive/reactive forces when embedded in sauropod
tissue?

Don

--- don ohmes <d_ohmes@yahoo.com> wrote:

> >From a practical perspective, I find Dr. Manning's
> scenario much more convincing than the "ninja
> warrior
> w/ a toe-dagger" image. I find the crampon analogy
> apt,  and feel that these animals were well-equipped
> for merely for "hanging on" but actually climbing;
> not
> towards the tops of trees or mountains, but toward
> the
> vulnerable areas of sauropods/large herbivores.
> Also,
> improving traction of the hind legs allows more
> force
> to transmitted to be from the jaws to prey.
> 
> Don
> 
> --- Dino Guy Ralph <ralph.miller@alumni.usc.edu>
> wrote:
> 
> > Do we know enough about the keratin exterior to
> > assess the function of this 
> > claw?
> > --------
> > "Dino Guy" Ralph W. Miller III
> > Docent at the California Academy of Sciences
> > proud member of the Society of Vertebrate
> > Paleontology
> > ----- Original Message ----- 
> > From: "Allan Edels" <edels@msn.com>
> > To: <dinosaur@usc.edu>
> > Sent: Wednesday, October 12, 2005 9:08 AM
> > Subject: Dino reputation 'is exaggerated'
> > 
> > 
> > > >From the BBC:
> > >
> > > http://news.bbc.co.uk/1/hi/sci/tech/4332272.stm
> > >
> > >
> > > Text follows:
> > >
> >
> ====================================================
> > > Dino reputation 'is exaggerated'
> > >
> > > The dimensions of the hydraulic limb reflected
> > what is known from the 
> > > fossil record
> > >
> > > The _Velociraptor_ dinosaur made famous by the
> > Hollywood movie Jurassic 
> > > Park may not have been quite the super-efficient
> > killer we all thought.
> > > Like other dinos in its family, it had a
> > distinctive sickle-shaped claw on 
> > > the second toe which many have assumed was
> > employed to disembowel victims.
> > >
> > > But tests on a mechanical arm suggest this
> > fearsome-looking appendage was 
> > > probably used just to hang on to prey.
> > >
> > > UK scientists report their experiments in the
> > journal Biology Letters.
> > >
> > > "This dispels the myth in place for some 40
> years
> > that this was a 
> > > disembowelling claw - this is not the case,"
> says
> > Dr Phil Manning, from 
> > > the Manchester Museum, University of Manchester.
> > >
> > > "I'm saying that the primary function of this
> claw
> > was to hold on to the 
> > > prey, effectively like a climber's crampon," the
> > curator of palaeontology 
> > > told the BBC News website.
> > >
> > > _Velociraptor_ belonged to the Dromaeosauridae,
> a
> > family of small to 
> > > medium-sized, lightly built and fast-running
> > dinosaurs from the Cretaceous 
> > > Period (146 million to 65 million years ago) who
> > appear from the fossil 
> > > record to have been very effective predators.
> > >
> > > There is even evidence some, such as
> > _Deinonychus_, hunted in packs.
> > >
> > > They all possessed a large, curved claw on their
> > big toes that could 
> > > rotate through an arc in excess of 200 degrees.
> > >
> > > By kicking and slashing, it has been widely
> > thought these creatures could 
> > > quickly open up their unfortunate victims,
> either
> > killing them outright or 
> > > making them bleed so profusely death followed
> very
> > quickly.
> > >
> > > Dr Manning and his team tested the reputation on
> a
> > robotic arm fitted with 
> > > a life-like Dromaeosaur claw. The set-up was
> based
> > on detailed fossil 
> > > measurements.
> > >
> > > The mechanical limb mimicked the sort of kick
> that
> > might have come from a 
> > > 2m-long, 40kg _Velociraptor_. The Kevlar and
> > carbon-fibre-coated aluminium 
> > > claw was thrust into the flesh from pig and
> > crocodile carcasses.
> > >
> > > Instead of producing the expected slashing
> wounds,
> > the robotic impacts 
> > > created only small, rounded punctures.
> > >
> > > What is more, the way the skin tissue bunched
> > under the impacts prevented 
> > > the claw from withdrawing easily.
> > >
> > > The punctures had a depth of about 30-40mm.
> > >
> > > "It seems highly unlikely that wounds of this
> > depth would have posed a 
> > > danger to the vital organs of a large
> herbivorous
> > dinosaur, though they 
> > > would obviously be fatal to small prey," the
> team
> > writes in Biology 
> > > Letters.
> > >
> > > Dr Manning does not want people to think less of
> > _Velociraptor_ or 
> > > _Deinonychus_ because of the research.
> > >
> > > Its killing efficiency may not have matched
> their
> > Hollywood image but the 
> > > creatures would still have presented a
> terrifying
> > prospect.
> > >
> > > "It's effectively like a fatal embrace," he told
> > the BBC News website.
> > >
> > > "These claws were used to hook into the flanks
> of
> > prey larger than them so 
> > > the jaws could do the despatching.
> > >
> > > "Imagine the scene: it's the Lower Cretaceous,
> and
> > Tenontosaurs (large, 
> > > plant-eating dinosaurs) are grazing on ferns or
> > cycads, going about their 
> > > everyday business," he added.
> > >
> > > "Unbeknown to them, you've got a pack of
> predators
> > stalking them.
> > >
> > > "First, [the Dromaeosaurs] try to separate the
> > animal they wish to kill by 
> > > running into the pack.
> > >
> > > "The lead attacker then jumps on to the flanks
> of
> > the animal, followed by 
> > > maybe two or three others, hooking the huge
> claws
> > in their feet into the 
> > > animal and holding on with the re-curved claws
> on
> > their hands.
> > >
> > > "And once they're hooked into their prey, the
> > razor sharp teeth of their 
> > > jaws go to work causing as much blood loss as
> > possible to weaken the 
> > > animal.
> > >
> > > "Eventually, the other animals come over for the
> > kill, probably ripping 
> > > open the throat and stomach with their teeth -
> not
> > their claws."
> > >
> > > The results of research were first shown on The
> > Truth about Killer 
> 
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