Geoscience Reference
In-Depth Information
ciraptor
's left foot was positioned just below the
Protoceratops
' head shield, close
toitsneck;itslefthandwasgraspingtheheadshield.Restassured,thiswasnotlike
a kitten and puppy wrestling with one another, nor was it like any other hint of in-
terspecies play,butmoreemblematic ofTennyson's“nature, redintoothandclaw.”
Paleontologists who studied these fossils agree that both dinosaurs must have been
buried instantaneously, which probably happened from the collapse of a nearby
sand dune, a geological referee abruptly and permanently stopping the fight.
So one would think by now that trace fossils would again come to the rescue
with evidence of dinosaur mating, arising and proudly pointing to dinosaurian con-
gress. Surely sediments somewhere, sometime, during the more than 160-million-
year history of dinosaurs recorded visible signs of a male and female dinosaur con-
ducting a Mesozoic version of “business time.” Alas, the answer thus far eludes us,
a postponing of evidence that tries the already-stretched patience of intellectually
lustypaleontologistswhodesperatelyseekthewarmafterglowofscientificgratific-
ation that comes from a sudden, ecstatic release of suspense.
Fortunately, ichnology, like all sciences, has predictive power, promising
deeply satisfying scientific insights that happen multiple times and in rapid suc-
cession. Through the use of modern traces and animal behavior, we can paint pic-
tures of what dinosaur mating traces should look like, and use those conjectured
imagesasguidesfordetectingmatingtracefossilspreservedinthegeologicrecord.
Of course, when looking for such double-entendre traces, paleontologists will have
to adjust their search images according to dinosaur anatomies, sizes, and behaviors
that may have left their marks while making the horizontal bedrock.
For theropods, such traces would have varied with the size of the mating di-
nosaurs involved. For example, the mating traces of a pair of
Microraptor
—each
weighing less than a kilogram (2.2 lbs.)—should have left much less of an impres-
sion compared to traces made by a pair of
Spinosaurus
, which together would have
made for 8 to 15 tons of convivial society. Still, mating traces of these bipedal di-
nosaurs would show a basic pattern of one or two footprints adjacent to one anoth-
