Problematic fossil
Hyperostosed neurocranium fossil from unknown bony fish
Common name: Tilly bone (Hyperostosic bone)

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                       5 6
Click Here higher magnification of surface features (photo 6)

7 8

This is dense and as heavy in the hand as a rock of the same size.
Not to be confused with the lighter weight of Pleistocene bone.

This fossil is one of two (almost identical) specimens brought to us over a period of several years by
individuals seeking identification. The first fossil was said to be found on a Missouri River gravel bar
while the second one, illustrated here, was purchased a few years later when a Midwest school's
science lab was closed and all its contents were sold. It was purchased without identification or
locality information. Photographs of the fossil were taken to help in the search for an identification.

These fossils are problematic. Most publications we have found deal with modern fish. Both fossils
have a strikingly similar appearance. They appear to be from the same or similar species. If this fossil
has been studied it should have a scientific name and supporting documentation.

Similar fossils (purchased on eBay)
* Incorrectly identified as: "Sea Brains" and Fossil Fish Ballast Organs
   Miocene - Bone Valley Formation - Sarasota, Florida

Click on picture

Bilateral symmetry is the main feature of a hyperostosid ("Tilly") bone.

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Paleontology and Geology of Missouri
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