Geoscience Reference
In-Depth Information
Onland,gastrolithsmighthavehadachancestayinginorclosetoadinosaur's
body. However, once that body was opened, whether by predators, internal decay,
scavengers,orjusttheravagesoftime,thesegastrolithscouldhavescatteredaround
those remains or been accidentally consumed by whatever was eating the dinosaur.
The same would have been true for a floating carcass scavenged by sharks or mar-
inereptiles.Theseanimalscouldhaveeitherhastenedgastrolithdeparturesfromdi-
nosaur bodies while tearing open a dinosaur's body cavity, or inadvertently eaten
some while enthusiastically noshing on dinosaur entrails. All of these considera-
tions mean that gastroliths may have been deposited far away from a dinosaur body
and gone through multiple “lives” as trace fossils.
In2003,paleontologistOliverWingsdecidedtofindoutunderwhatconditions
gastroliths might stay or go after the death of a dinosaur. In setting up this research,
he asked himself what happened to gastroliths in modern dinosaurs—ostriches
(
Struthio camelus
)—after they died and their gastrolith-holding bodies were placed
in different environments. Following the death of two ostrich chicks from bacterial
infections on a South African farm, he donated their bodies to science by watching
their corpses decay for six days. One chick, the smaller one of the two—weighing
only2.1kg(4.5lbs),oraboutthesizeofaroasterhen—wasleftoutintheopenand
on land, where both South African sunshine and cadaver-loving insects quickly got
to work on it. Meanwhile, he placed the other, much larger chick, which weighed
11.5 kg (25 lbs), in an uncovered water-filled barrel. After three days, he turned
over each body so that both sides had been exposed to air and water, respectively.
The results were surprising. In the land-based chick, its gastroliths stayed put.
Although insects, dehydration, and bacterial decomposition successfully caused
rapid weight loss, tissues tightened around the gastroliths in its crop, a biological
shrink-wrap that kept all of these stones together and in one place. In contrast, the
water-immersed chick lost very little flesh, but it opened up and lost all of its gast-
roliths, which fell to the bottom of the barrel. Although quite simple and limited to
only two samples, this little experiment gave Wings and other dinosaur paleontolo-
