Geoscience Reference
In-Depth Information
supposedgastrolithsfoundwiththeselarger,well-toothedtheropodsmaybeeviden-
ce of accidental ingestion, whether through gulping down a prey animal with gast-
roliths or swallowing stones underneath the body of an animal as it was eaten. In
fact, the few gastroliths in the abdominal cavity of the small theropod
Sinocalliop-
teryx
havebeenattributedtoinadvertentgulping,unknowinglyincludingthemwith
ameal.Still,somelargetheropodshavedefinitegastrolithsintheirbodies,thusdir-
ectly disputing the previously held idea that only sauropods and plant eaters made
use of gastroliths.
There is one additional and important facet of this continuing debate that has
yet to be mentioned regarding theropods and gastroliths. Remember the very first
description of gastroliths by Eudes-Deslongchamps in
Poekilopleuron
, in 1838?
Well,
Poekilopleuron
was not only a theropod, but also a big one, estimated to
have been about 9 m (30 ft) long. From a dinosaurian perspective, this matched an
average-sized
Allosaurus
and was about 3/4 the length of an adult
Tyrannosaurus
.
Yes, that's right, gastroliths in dinosaurs as a concept actually began with them in a
verylargetheropod,notsauropods.Unfortunately,wecan'tstudytheoriginalbones
of
Poekilopleuron
, as these were lost in bombing raids during World War II. Nor
can we study the original gastroliths as they too have been lost, which from an ich-
nological standpoint is an even greater tragedy. Still, we are left with this satisfying
pieceofpaleontologicalhistorythatconnectedtheropodswithgastroliths,whichwe
are now revisiting with much vim and vigor through their discovery in many other
theropods of varying clades and sizes.
What's even more exciting about this renewed recognition of gastroliths in
theropods is how it coincides with the evolutionarily based revelation that birds are
dinosaurs,asmanymodernbirdshavegastroliths,too.Ofthesmalltheropodsfound
with undoubted gastroliths in their abdominal cavities, some of these—such as
Caudipteryx
,
Sinocalliopteryx
, and
Sinosauropteryx
—also have feathers. Although
gastroliths are trace fossils and mostly reflect behavior, which is more fluid and
open to interpretation and variety than genetically determined anatomy, natural se-
