Geoscience Reference
In-Depth Information
CHAPTER 2
These Feet Were Made for Walking, Running,
Sitting, Swimming, Herding, and Hunting
Why Dinosaur Tracks Matter
If through some miraculous disaster every dinosaur bone in the world disappeared
tomorrow (or the next day, for that matter), the fossil record for dinosaurs would
still be represented quite well by their tracks alone. The main reason for this is very
simple: eachdinosauronlyhad,onaverage,abouttwohundredbonesperindividual.
Yet you could bet that those dinosaurs that made it from mere hatchling to rambunc-
tious juvenile to surly angst-filled teenager to a full-fledged responsible adult prob-
ably made many more than 200 tracks during their lifetimes. This supposition alone
implies—although we'll never know for sure—that dinosaur tracks probably far out-
number their bones in Mesozoic rocks worldwide.
The number and variety of dinosaur tracks out there is astonishing. Thus far, di-
nosaur tracks have been found in eighteen states of the U.S. and on every continent
except for Antarctica, with thousands of newly discovered ones each year. Dinosaur
tracks range in latitude from the North Slope of Alaska to southern Argentina, and
are in rocks dating from the beginning of dinosaurs, about 230 to 235 million years
ago (
mya
), to their very end, 65
mya
. Although it's tempting to think of all dino-
saurtracksaspotholesthatwouldeasilyswallowatricycleanditsdinosaur-admiring
rider,tracksalsovariedinsizefromlessthanthewidthofathumbnailtodepressions
that could be used to park a Smart Car.
Other than their sheer abundance, another comforting thought about dinosaur
tracks is that they very often are in places where dinosaur bones are rare or absent.
Moreover, they also convey snapshots in time, reflecting a vast variety of dinosaur
behaviorsinthemoment,tellingusaboutaformerdinosaurpresenceinagivenplace
