Utah Gastrolith - A Controversial Rock
 
My dad found this rock while hunting for dino bone in the Morrison Formation in Utah where a lot of dino bone has been found. This one iswirls of color! People often don't realize that there was also great agate waiting to be swallowed by dinosaurs 75 million years ago.
 
When I was a kid, there was a large, complete dino herbivore femur at least five feet long that was my playground. My dad gave it to the Prehistoric Museum in Price, Utah. He had literally hundreds and hundreds of pounds of dino bone in a storage room. He sold or traded it away before he died. I was shocked to see the room where he kept it, empty and bare, when I disposed of the family property.
 
My point is that my dad had a better opportunity to actually find dino gizzard stones than just about anybody. You can read a longer essay about gastroliths at the blog page, KinesavaTALKS.
 
What’s a “Gastrolith” ?
 
There's seldom any doubt about whether a rock is actually dino bone. But dino gizzard stones have traditionally been very controversial - more than just about any rock you can think of because many paleontologists have maintained that they're not really different from beach agate.
 
A brief search will clearly illustrate the problem. There are lots of "Gastroliths" for sale online. Different people are asking for a VERY wide range of prices. They range from around $10 each all the way up to (Gaaakkk!) $3,500. I guess that all it would take is one person willing to pay that much.
 
Wikipedia has a great article about Gastroliths that I highly recommend. I've been writing about my dad's Gastroliths for years now and I notice that the Wikipedia article has recently been thoroughly revised.
 
https://en.wikipedia.org/wiki/Gastrolith
 
The Wikipedia article now leans in the direction of saying that Gastroliths CAN be distinguished from beach agates.  (It used to lean the opposite way.)
 
"Gastroliths can be distinguished from stream- or beach-rounded rocks by several criteria: gastroliths are highly polished on the higher surfaces, with little or no polish in depressions or crevices, often strongly resembling the surface of worn animal teeth. Stream- or beach-worn rocks, particularly in a high-impact environment, show less polishing on higher surfaces, often with many small pits or cracks on these higher surfaces. Finally, highly polished gastroliths often show long microscopic rilles, presumably caused by contact with stomach acid."
 
The Wikipedia article also includes a picture of some Utah Gastroliths! (see the pic above).
 
I remember Starr Springs!!!  It's there on the flanks of the Henry Mountains. My dad drove his Jeep past it a lot on our trips into the desert.