Geoscience Reference
In-Depth Information
Dinosaurs on the Run
Youmightbethinkingbynow,enoughaboutthehypotheticalandanachronist-
ic races with humans and talking about dinosaur tracks as theoretical objects. What
was the fastest dinosaur ever interpreted from a dinosaur trackway? How fast were
they, really, especially when compared to the speediest of humans or modern mam-
malian predators such as lions or cheetahs?
Most animals spend much of their time moving at a normal pace. Among hu-
mans, even marathon or ultramarathon runners normally do not spend more than
15% of any given day running and, let's face it, they're not sprinting throughout
even that time. Hence, a reasonable reflexive prediction about dinosaurs is that
whenever they were making tracks, they were walking. Running would have been
quite rare and reserved only for emergencies, such as chasing down prey, not be-
coming prey, or avoiding other dire threats such as forest fires, floods, or storms.
Sure enough, these expectations about dinosaurs mostly taking leisurely strolls are
probably right. Whenever the Alexander formula or variations of it are applied to
dinosaur trackways, most dinosaurs were simply walking.
Still, finding exceptions to a norm is one of the joys of science. Thus when pa-
leontologists encounter tracks that indicate sprinting dinosaurs, they justifiably get
reallyexcited.Sofar,almostalltrack-waysinterpretedasthosemadebyrunningdi-
nosaurs were made by bipedal ones, theropods and ornithopods. In contrast, only a
fewtrackwaysoftrottingquadrupedaldinosaursareknown.Oneofthese,preserved
in Late Cretaceous rocks of Bolivia, was made by an ankylosaur—a big, armored
dinosaur—which must have looked like a living tank as it ambled along. Sadly, not
one trackway yet shows that sauropods, ceratopsians, or other quadrupedal dino-
saurs loped, galloped, pranced, orminced. However,this does notnecessarily mean
these animals only walked. Just remember that running is rare in all land animals,
which means the likelihood of finding fossilized tracks of running quadrupedal di-
nosaurs is also quite small.
