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maybe a few other plant-eating dinosaurs such as hadrosaurs, and almost never in
theropods, stegosaurs, ankylosaurs, or ceratopsians. Second, these gastroliths were
used to help grind up hard-to-digest food in gizzard-like organs because sauropods
did not have the right teeth for chewing their food. Related to these two assump-
tionswasthetacitagreementthattheropodslackedgastrolithsbecausetheywereall
carnivorous, with big, sharp, pointy teeth, powerful jaws, and marvelously corros-
ive stomach acids. In other words, only wimpy herbivorous dinosaurs needed these
digestive aids.
We now know that this story about gastroliths and dinosaurs, neatly framed,
displayed in a prominent place, and highlighted with artfully angled lighting, is
mostly wrong. Given what we've learned about the varied uses of gastroliths in
modern animals, combined with a broader knowledge about dinosaur diversity,
evolution, and behavior, and all topped with healthy distrust about what constitutes
a real dinosaur gastrolith, this picture, much like paleontologists' wardrobes, has
changed considerably since the days of Barnum Brown.
First of all, the dinosaurs that are now the most likely to have gastroliths are
not
the plant eaters, but theropods. Yes, youread that right: some ofthose meat-eat-
ing, über-macho, Mesozoic killing machines of yore may have needed a little help
from their geological friends. Among the theropods documented thus far with gast-
roliths are: the Early Jurassic
Megapnosaurus
(previously known as
Syntarsus
); the
Late Jurassic
Nqwebasaurus
; the Early Cretaceous
Caudipteryx
,
Shenzhousaurus
,
Sinocalliopteryx
, and
Sinosauropteryx
; and the Late Cretaceous
Sinornithomimus
,
among others.
Well, of course these theropods had to use gastroliths, you might say. These
aresmall,effetetheropods,someofwhich,suchas
Nqwebasaurus
,hadnubbyteeth,
and
Sinornithomimus
, which completely lacked teeth. But then tell that to more im-
posing theropods such as the Late Jurassic
Allosaurus
and
Lourinhanosaurus
, the
Early Cretaceous
Baryonyx
, or the Late Cretaceous
Tarbosaurus
, all of which have
had possible gastroliths directly associated with their skeletons, too. Granted, the
