Geoscience Reference
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stomach acids were sufficient for digesting anything consumed by a theropod. Al-
though no one has yet found gastroliths directly associated with
Struthiomimus
,
some of its relatives, collectively called ornithomimids (“ostrich mimics”), do have
them. This fact has prompted paleontologists to start thinking about what these
theropods might have eaten other than meat: insects, plants, or a blend of both? Or
didthesegastrolithshavesomeotheruseswestilldon'tquiteunderstand?Andwhy
would some herbivorous dinosaurs with teeth unsuited for chewing, such as most
sauropods or stegosaurs,
not
have gastroliths?
Speakingoffood,yetanotherdimensionofdinosaurbehaviorthatismuchbet-
ter comprehended through their trace fossils regards what they ate. Traces woven
into the opening narrative, such as healed bite marks, toothmarks on bones, wear
on teeth caused by plants, and coprolites (fossil feces), tell us much more about di-
nosaur dietary choices than any other means of fossil evidence. For instance, we
can now surmise that
Edmontosaurus
and
Triceratops
must have been quite tasty
forsometyrannosaurs.Thisisbackedbyhealedtoothmarkscausedbyalargepred-
atory theropod preserved in a few bones of
Edmontosaurus
, including at least one
with a smoking gun (or tooth, as it were) linking it to
Tyrannosaurus
or its close
relatives.
Triceratops
bones also bear toothmarks that could only have been made by
tyrannosaurs, including those that mark the front of the face and others showing
where they grabbed a
Triceratops
head shield to separate its head from the rest of
its body. Amazingly, not one but two colossal coprolites attributed to tyrannosaurs
have been documented, each with finely ground bone and one containing fossil-
ized muscle tissue. From coprolites, we also suspect that at least some Late Creta-
ceous hadrosaurs ate rotten wood. (Why? Sorry, can't reveal everything just yet.)
We even figured out from dinosaur coprolites that at least a few animals—namely,
dung beetles—depended on dinosaur feces as “manna from heaven” to ensure their
survival. Hence, these trace fossils bring us much closer to reconstructing ancient
