Geoscience Reference
In-Depth Information
Since Alexander first came up with this formula, it's been prodded, probed,
tweaked, and otherwise tested to see how well it works, or not. Not surprisingly,
then, other paleontologists have come upwith their ownformulas forestimating di-
nosaur speeds. A few have even tried to say that some dinosaurs were not capable
of running at all, a supposition based on analyses of dinosaur skeletons, probable
ranges of motion, and muscle masses that would be required to propel a multi-ton
animal forward at high speed. Nonetheless, Alexander's original formula still en-
dures and is normally the first that paleontologists reach for when they find a dino-
saur trackway and want to know how quickly that dinosaur was moving.
This is probably where the gentle reader, who has seen supposedly sophist-
icated mathematical models undergo complete failures, might wonder if other fea-
tures in a dinosaur trackway tell whether a given dinosaur was speeding up, slow-
ing down, or otherwise varying its pace. For one, the width of the trackway should
get narrower as a dinosaur increased its speed, and wider if it slowed down. Think
about howa full stop bya
Triceratops
would showall fourfeet planted at the width
of the shoulders and hips; in contrast, a full gallop would have registered the feet
more toward the centerline of its body. A general rule for both bipedal and quad-
rupedal track-ways: the narrower the trackway, the more likely the trackmaker was
moving quickly.
Don't believe me? Fine with me, as science thrives on disbelief and testing. If
youhaveadog,haveitwalk,trot,andthenrundownthebeach,andyouwillseeits
trackway width become visibly narrower along the way. The reverse will happen as
yourdogslowsdowntoastop,feetplantedatshoulderandhipwidths,tailwagging
happily.
For another independent way to test dinosaur speed, you can look at how each
footprint is a record of how much ground beneath a dinosaur was disturbed by its
movement. This is an experiment that can be readily performed on the same sandy
beach you used for your dog experiment, and you can use your dog again, or even
yourself. Tracks made by walking show little disturbance of the sand around and
