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RE: New dinosaur paper: Ankylosaur tail club smacking

This question suggests another more specific: what happens when the predator
gets so close that the tail club 'knob' passes beyond the target, and
contact is made instead by the 'handle'? Obviously it would be pretty
strong, as a composite bundle of vertebrae, ossified tendons, muscles,
ligaments and skin, but for some impacts it would surely be at risk of
snapping when wrapped around a tyrannosaur tarsus (or whatever). More of a
challenge for someone to model, but just as relevant!

I'd also be interested in a comparison of anatomy and function among
ankylosaurs, glyptodonts and meiolaniid turtles. How detailed is the

Dr John D. Scanlon, FCD
Riversleigh Fossil Centre, Outback at Isa
"Get this $%#@* python off me!", said Tom laocoonically.

-----Original Message-----
From: Augusto Haro [mailto:augustoharo@gmail.com] 
Sent: 28 August, 2009 1:34 AM
To: tijawi@yahoo.com
Cc: dinosaur@usc.edu; afarke@gmail.com
Subject: Re: New dinosaur paper: Ankylosaur tail club smacking

Does not it seem difficult for just the tip of the tail to just hit
such a small point of the anatomy of a large carnivorous dinosaur such
as the ankle/lower limb? It would require calculation and precise
positioning of the herbivore to put the ankle of the theropod in line
with the trajectory of the tip of the tail... (unless the ankylosaur
hitted all the time the predator was around, just in case it hits the
limb once). Is there any unequivocal evidence of a large theropod bone
hitted by these clubs?

Perhaps the device can have more chances of functioning against small
predatory dinosaurs, moreover packs of these, or predators whose main
bodies are at the height of the club, such as large crocs. Doedicurus,
a glyptodont with a similar tail club lived along with much smaller
predators (and perhaps along with large crocodylians such as

2009/8/27 Tim Williams <tijawi@yahoo.com>:
> Andrew Farke <afarke@gmail.com> wrote:
>> I've briefly blogged about the new
>> ankylosaur function article at the
>> Open Source Paleontologist:
>> http://openpaleo.blogspot.com/2009/08/new-paleo-paper-in-plos-one.html
> As stated in the abstract, "Large knobs could generate sufficient force to
break bone during impacts, but average and small knobs could not".  But I
wouldn't have thought that average and small knobs were therefore
non-functional as defensive devices against predators.  It would not be
necessary for the ankylosaurid to debilitate the predator by breaking bone,
but simply to warn the predator off.
> The predator wouldn't *know* that the swinging tail club of a smaller or
mid-sized ankylosaur would not break its ankle.  The fact that the blow
would hurt (and probably quite a lot!) is reason enough to avoid it.  If the
predator was struck by an undersized tail club, the pain inflicted by the
blow would tell the predator that there is the *potential* for a
debilitating injury (even if, biomechanically, there isn't enough impact to
smash through bone).  The predator may have even have witnessed (or
experienced itself) a blow from a large tail club to be aware of the
> In other words, for ankylosaurids as in politics, perception is more
important than truth.  If a predator perceives a tail club to be dangerous
(because in larger ankylosaurids it really is), then it will avoid it, for
fear of incurring a crippling injury.
> Cheers
> Tim