5.5" Dinosaur Coprolite Fossil Polished Slab Specimen Poop Dung Harry Mountain Utah

Location: Harry Mountain, Morrison Formation, Utah

Weight: 2 Pounds 1.1 Ounces 

Dimensions: 5.5 Inches Long, 2.8 Inches Wide, 2.8 Inches Thick

The Item pictured is the one you will receive.

Dinosaur Coprolites, or fossilized feces, are a significant category of trace fossils that provide direct evidence of the dietary habits, digestive physiology, and ecosystems of extinct organisms. In Utah, these specimens are predominantly found in the Morrison Formation, a vast sequence of Upper Jurassic sedimentary rocks dating to approximately 150 million years ago. Unlike body fossils, which reveal an animal's morphology, coprolites offer a "snapshot" of biological behavior, such as predation or herbivory. The recognition of these fossils was pioneered by William Buckland in 1829, who identified them as excrement rather than the "fossil fir cones" they were previously thought to be.

Geological Context and Mineralization

The coprolites discovered in Utah, especially near the Henry Mountains and San Rafael Swell, are famous for their distinctive preservation through agatization. Over millions of years, organic material was replaced by silica-rich minerals like chalcedony, quartz, and jasper. This process often creates a colorful, glass-like matrix that preserves microscopic internal structures. Although the biological material is absent, mineral pseudomorphs retain the shapes of undigested plant matter and seeds, as well as evidence of parasites.

Identification and Biological Origin

Most large coprolites from the Utah Morrison Formation are attributed to sauropods—the large, long-necked herbivores such as Apatosaurus or Diplodocus. Identification relies on size—some exceeding 60 centimeters—and the lack of bone fragments, which would suggest a carnivorous diet. Scientific studies have identified:

• Dietary Composition: Fragments of conifer wood, decayed vegetation, and knobby cuticles are common in the fecal groundmass.
• Chemical Markers: Elevated levels of calcium, magnesium, and phosphorus, indicating mineralized remains of the animal's last meal.
• Ecological Impact: Evidence suggests that methane generated by microbial activity in sauropod guts may have impacted the Mesozoic climate.