Geoscience Reference
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The answers to that rhetorical question are yes, no, and maybe, and not necessar-
ilyinthatorder.Thelikelihoodofcorrectlydiagnosingtheseenigmatic tracefossils
depends on slavishly asking and addressing a few important questions:
• Are the suspected gastroliths inside a dinosaur skeleton?
• Are there just a few of these stones, dozens, or more than a hundred?
• Are these stones clustered in a compact mass, taking up a small volume
compared to most of the dinosaur's body?
• Isthismassofstonesintherightlocationinthedinosaur'sskeleton,namely
its abdominal cavity?
• Are the stones appropriately sized for this dinosaur?
Ideally, if all of these criteria are fulfilled, gastroliths will also outline the ap-
proximate size and shape of whatever organ was holding it in a dinosaur, such as a
gizzard. Astrace fossils,then,thesecanactually helpfillinthatpartofadinosaur's
soft-part anatomy as a proxy.
However, if a dinosaur body is not associated with your gastrolith suspects,
then confirming that these rocks formerly resided in a dinosaurian alimentary canal
gets much tougher, albeit not impossible. When faced with an absence of bones but
with some possible gastroliths, you must ask a second set of questions:
• Are these rocks in strata of the right age for gastrolith-bearing dinosaurs?
• Are these rocks in strata of the right environments for dinosaurs?
• Are these rocks the right composition to have survived time in an acidic
environment: not limestone, but more like chert, quartz sandstone, or
quartzite?
• Do they have the same size, shape, and surface texture as those of known
gastroliths found inside dinosaurs?
Afewpaleontologistshavesuggestedthatifagastrolithisfoundoutsideofthe
body cavity of a dinosaur or other animal that used gastroliths, with nary a bone in
