Geoscience Reference
In-Depth Information
Similarly, stones of equal or different hardness mashing against one another would
have imparted a sort of microwear on gastroliths, evident as pits and gashes. These
marks also might have been from quartz sand or other minerals in the stomach, per-
haps including those on or in plants. Both types of microwear also involved much
muscular activity behind it, whether through gnashing of teeth or squeezing of giz-
zards. In principle, the only major difference with gastroliths is their exposure to
low-pH stomach acids, which presumably would leave a more chemical overprint.
Still,despitethesestudiesthatusedlasers,microscopes,andothertechnologic-
ally advanced tools to study suspected gastroliths, healthy skepticism about the re-
cognition of dinosaur exoliths in Mesozoic rocks still lingered well after the 1990s.
Regardless ofthese non-believers, though,thegoodnumberofgastroliths foundin-
side dinosaur skeletons in the early part of the 21st century ensures that paleonto-
logists have plenty more of these trace fossils to study, and bodes well for finding
more dinosaur gastroliths in the future.
Dinosaur Gastroliths? Get Real!
So how important are these dinosaur gastroliths, considering the continued skep-
ticism and theories that still surround them? First of all, despite previous attempts
to diminish these important trace fossils via the almost-clever pun “gastromyths,”
they really do exist. Admittedly, our views of gastroliths in dinosaurs have changed
considerably since their discovery. Yet a little history lesson about gastroliths helps
to understand just how far our concepts about these dinosaur trace fossils have pro-
gressed, with novel insights about them emerging in just the past ten years or so.
The earliest description of possible gastroliths in a dinosaur was in 1838,
whenFrenchpaleontologistJacquesAmandEudes-Deslongchampsnotedaboutten
pebbles underneath the ribs of the Middle Jurassic dinosaur
Poekilopleuron
, which
had been discovered in France. He concluded that these rocks were in this dino-
saur's stomach, just like those found in fossil crocodiles from the same area. Much
later, in the late 19th century and leading up to 1900, paleontologists began spot-
tinggastrolithsindinosaursandmarine-reptilecontemporariesofdinosaurs,suchas
