Geoscience Reference
In-Depth Information
Beforemovingontoexcitedlyinterpretingdinosaurbehaviorfromtheirtracks,
though, I should point out one minor disadvantage caused by how most tracks were
preserved. Dinosaur tracks, just like modern ones, were probably weathered soon
aftertheyweremade,placedunderassaultbytheerosiveeffectsofrain,wind,grav-
ity, and other animals stepping on them. This means that dinosaur tracks may not
reflect the original surface impacted by a dinosaur. Consequently, a common way
for dinosaur tracks to have made it into the fossil record was as
undertracks
. That
is, many of the tracks we see were actually transmitted below the surface where a
dinosaur walked, trotted, or ran.
This phenomenon is similar to how, when exerting pressure with a pen or pen-
cil while writing or drawing on a sheet of paper, an image of the writing or draw-
ing is also impressed on underlying pages. The decided preservational advantage of
this phenomenon is that such tracks were already buried, protecting them from de-
struction.Hence,allpaleontologistswhostudydinosaurtracksfirstassumetheyare
looking at undertracks, and only modify these realistic expectations if confronted
by the delightful details of skin.
In essence, if a dinosaur track shows pad and scale impressions from the foot
of its maker, only air separated the flesh of that dinosaur from the sediment pre-
serving it.
Any dinosaur track we find in the geologic record, though, is at the end of
its history. So we also have to throw in an additional dollop of skepticism when
divining any given track found at the same earth's surface we now occupy. Under-
tracks made by dinosaurs may have been spared weathering for as much as 200
million years, but once exposed they can quickly become blurred or erased com-
pletely by modern weathering. This is where paleontologists depend on the sharp
eyes and good graces of the general public, who far outnumber paleontologists and
perhaps are outside more often. Many a dinosaur track or trackway has been found
by hikers, bikers, or other recreationalists who recognized their patterns and then
didtherightthingbyreportingtheirlocations.Maybeitwillbeyourturnsomeday.
