thagomizer, Battat stego model

[Mike Bonham <bonham@jade.ab.ca>]

I have before me a model of `Stegosaurus ungulatus' in 1/40 scale, from
the Battat Toys line of solid rubber dinosaurs, designed `in collaboration
with the Museum of Science in Boston'.  It's very nice!  The thagomizer
spikes are horizontal (4 spikes each side) and the animal is shown standing
very tall (front legs too) with its tail rising higher than its head.

You may recall the animation in the PBS "Dinosaurs" program, of Stegosaurus
driving off an Allosaurus by thrusting with its vertically-oriented tail
spikes, and then going back to nibbling on the top of a cycadoid by standing
on its back legs.  The defensive thrusting motion looked somewhat awkward,
especially when in the same program Bob Bakker (I think it was he)
explained how very flexible the tail and body vertebrae would have been
in the side-to-side plane, but not necessarily in the vertical plane.  The
motion depicted would have required both, and a fair amount of coordination
to keep the spikes moving along their own axes (like throwing a dart).

With the new sideways spikes, I can much more easily imagine a carnivore
moving in for a bite to the head, neck or flank of a stego, and getting
stabbed in the back by the battery of spikes on that side with a relatively
uncoordinated clinch of the tail to the threatened side.  That would
provide some incentive for the predator (if it survived) to learn to avoid
stegosaurs, and for the stegosaurs to advertise their deadliness with
progressively bigger, flatter and more colourful plates.

Battat has a Stegosaurus, Styracosaurus, Dilophosaurus, Triceratops,
Gallimimus, Tyrannosaurus, a Diplodocus in the high-rearing tripod position,
and what look like, in the picture on the attached dog-tag blurb, Polacanthus,
Maiasaura, Megalosaurus and that spiny-necked African sauropod.
All of the models look quite nicely done.  T.rex, Maiasaura and Styracosaurus
are rather garishly coloured, but that's in vogue right now isn't it?

Their Stegosaurus has orangy-red plates, yellow under-body, and a brown
back with irregular brown stripes extending down the flanks.  It looks
rather lean and bony, with leg muscle definition and loose skin
over the shoulder girdle.  It has a bird-like hooked beak.  Ha!
I just noticed it even has a cloacal vent on the rear of the ventral
protuberance...an anatomically-correct dino model!

Well, are we tired of thagomizers yet?

Mike Bonham        bonham@jade.ab.ca      Jade Simulations International
``Organization is the enemy of improvisation.'' -- Beaverbrook