Dinosaur Gastrolith
Indeterminate gastrolith, cf. Sauropoda gizzard stone • Trace fossil, specifically a gastrolith (stomach stone) used by herbivorous dinosaurs for mechanical food digestion
Geological Period
Mesozoic Era, likely Cretaceous or Jurassic
Estimated Age
66 to 150 million years
Preservation Type
Siliceous or quartzose lithification with natural mechanical abrasion and weathering
Condition Assessment
Good condition; completely natural wear with a smooth tumbled surface, showing minor surface pitting and iron staining, intact without modern damage
Taxonomic Classification
Ichnotaxon: Gastrolith; associated broadly with Sauropoda or large Ornithopoda
Morphological Description
Smooth, rounded, water-worn appearance with a distinct polish and blunt sub-triangular shape. The surface exhibits a high degree of rounding (abraded through gastric churning), with minor iron-oxide staining giving a reddish-brown patina. No visible organic structures, but features characteristic wind-polish or mechanical smoothing typical of internal organ churning.
Rock Matrix
Dense quartzite or fine-grained siliceous sandstone matrix, heavily oxidized with iron staining
Formation & Location
Morrison Formation (Western United States) or Cedar Mountain Formation; commonly found in continental fluvial deposits where dinosaur remains occur
Size & Dimensions
Approximately 10 to 15 cm in maximum length, consistent with medium-to-large sauropod or large ornithopod gastroliths
Value & Rarity
Estimated Market Value
20 to 50 USD
Auction Estimate
15 to 40 USD
Rarity Assessment
Common in specific geological formations, though isolated finds without clear context or association can be difficult to definitively verify as true gastroliths versus stream-rounded pebbles
Scientific Significance
Provides direct evidence of herbivorous dinosaur digestive behavior, metabolic processes, and terrestrial paleoecology. Gastroliths also offer clues about ancient migration patterns when the source rock can be matched to distant geological formations.
Preparation Recommendations
No invasive preparation required. Light brushing to remove surface dust. Store in a stable, dry environment. Can be displayed on a small acrylic ring mount.
Notable Features
Distinct polished surface texture indicative of prolonged internal grinding within a dinosaur gizzard, coupled with deep reddish-brown iron oxide patination.