Geoscience Reference
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is a very handy one to identify quickly, especially in a remote field area.) We also
can get a better understanding of gaits by measuring distances between alternating
feet(
pace
),betweenthesamefoot(
stride
),andthewidthofthetrackway(
straddle
).
Many other measurements can be taken from a trackway, but these three are essen-
tial and constitute a good start in their study.
Can these same principles be applied to dinosaur trackways, in which you can
just glance at a dinosaur trackway and excitedly shout “Theropod!” “Ornithopod!”
or“Barney!”(whatevertheheckheis)?Theansweris,mostly,yes.Partofthisiden-
tification is aided by the obviousness of some tracks, which are then confirmed by
trackway patterns. For example, if you see bathtub-sized depressions that express
themselves in an alternating diagonal pattern, you will probably not shout “Baby
theropod!” Furthermore, sauropod tracks normally show a slow walking or “un-
derstep” pattern in which the rear foot did not quite fall in the same place as the
front foot; appropriately, its stride is short, too. In a few instances, their rear tracks
registered directly on top of (and hence wiped out) their front tracks, indicating a
slightlylesssluggishpace.Sofar,Ihaveonlyseenonesauropodtrackwayinwhich
the rear feet were placed ahead of the front feet on the same side, approaching what
we might call a “trot.” This trackway was from a relatively small sauropod, which
might have been a juvenile that didn't know it wasn't supposed to run.
Speaking of sauropod trackways, their patterns can be further placed into two
categories based on their widths:
narrow gauge
and
wide gauge
. These terms are
borrowed from railroads, in which the rails are either narrowly spaced (light rail)
or widely spaced (freight trains). For bipedal dinosaurs like theropods and most or-
nithopods, their normal trackway patterns show they were walking, although some
have been interpreted as slow walking, fast walking, or running. Their trackways
haveanalternatingright-left-rightpattern,andmostareprobablynarrowerthanthe
body width of the dinosaur that made them, especially for theropods. They did this
by rotating their legs inward with each step forward, as if they were fashion models
sashaying down a runway.
