Geoscience Reference
In-Depth Information
tracks provide some insights on dinosaur hunting behaviors? All of these are good
questions, and I'll do my best to answer them through what dinosaur tracks tell us.
Probably the most famous and longest-known example of a possible “stalking
theropod” trackway comes from near Glen Rose, Texas. This trackway, discovered
by paleontologist Roland Bird in 1938, was in a limestone bed cropping out in the
Paluxy River. He noticed the trackway in direct association with a sauropod track-
way, and was thrilled to see how the theropod tracks at first paralleled and then in-
tersected those of the sauropod; at this point, the theropod tracks ceased. Bird sur-
mised that this was where the theropod leaped onto the left side of the sauropod to
bring it down, just like a lion would with its prey.
“Wow, that sounds incredible!” you think. Yes, it does, which also means the
story may not be so simple. For one thing, the sauropod tracks continue on past
where the theropod tracks stopped, and show no alteration of gait or depth of tracks
on the left side. One would think that the addition of a multi-ton predator on one
sidewouldcausesomereaction,oratleastalittlebitofimbalance.Sonowthemore
reasonable explanation is that, yes, the theropod might have been stalking the saur-
opod but did not jump onto it there. Instead, the tracks just weren't preserved after
the point where they disappear. So we don't really know whether the theropod was
goingafterthissauropodornot.(Bytheway,ifyouwanttoseethistrackway,don't
gotoTexas,unlessyoulikelookingatrectangularholesinriverbedsthere.In1940,
Bird and many laborers extracted the trackway and took it to New York City, where
it is now displayed in the American Museum of Natural History.)
Within a mile of this trackway, though, are elongated dinosaur tracks that may
reflect evidence of stalking behavior, connecting to speculations mentioned pre-
viously that some theropods went fishing. Glen Kuban, a paleontologist who has
studied and mapped the Paluxy River dinosaur tracks for more than twenty years,
wondered whether a few of the theropod tracks there were a direct result of their
stalking fish in shallow water, like modern grizzly bears seeking salmon. His reas-
oning was based on how a few trackways show where their makers went from nor-
