Geoscience Reference
In-Depth Information
watched songbirds around puddles knows how they partially immerse themselves,
and then shake their bodies to ensure that all of their feathers get wet. Although the
body of water itself will not preserve traces of this activity, moist mud or sand on
their banks and shallow bottoms might record a curious series of tracks, perhaps
with splatter marks on emergent areas next to the water.
So now think of, say, a 1.5-ton
Gigantoraptor
from the Late Cretaceous, one
perhaps rejected by a potential mate. In an attempt to better its health and appear-
ance, it decides to take a dust, sun, or water bath. Now envisage the marks these re-
spective behaviors might have produced. A
Gigantoraptor
dust bath would be a re-
lativelyshallowsemicircularstructure,butenormouscomparedtothoseofallmod-
ernbirds,probablymorethan5m(16ft)wide.Linkingthiswallowtoalargethero-
pod could be tough, but doable if it also rolled its neck and head on the ground out-
side of the main depression, giving more anatomical clues. In contrast, sunbathing
would have left body, wing, and tail impressions, with some movement blurring
their outlines but not as much as in a dust bath. A water bath would perhaps show
a series of walking tracks going from less saturated to more saturated (gooey) sed-
iments, a stopping pattern, then lots of tracks in a small area caused by shuffling of
the feet; water droplets on the shoreline and on top of the tracks there would com-
plete the picture. Hopefully this mental exercise serves as yet another example of
how modern bird traces can act as predictors for what trace fossils might be out
there waiting to be recognized, and the behaviors that might be divined from them.
Bird Intelligence and Tools as Traces
At one time, the phrase “bird brain” was an insult hurled at someone perceived to
lack common sense. Nowadays, it should be taken as a compliment. Paralleling the
extrememakeoverfordinosaursshowingtheywerenotslowreptilian-likedullards,
research on bird behavior in the past thirty years or so has completely changed our
view of birds as simplistic automatons obeying their genetic codes. Instead, we are
increasingly seeing birds more as sophisticates with their own complicated indi-
