A disarticulated cranium and mandible partially encased in an extremely hard plastic material were discovered in a riverbed in Pennsylvania.
Several traditional fossil-preparation methods were used to extract the fragile skull from the plastic.
The disarticulation suggested that the cranium and mandible were most likely skeletonized at the time of their immersion into the liquid plastic.
The plastic itself was potentially an important clue.
Its chemical composition indicated that it was similar to the plastic used in kitchen countertops, not commonly sold to the public in the quantity that was used to encase the skull.
The results were compared using the modern bomb curve.
The skull revealed pre-1950 levels of radiocarbon, and thus it was not of recent origin.
On August 1, 1999, a poorly preserved metal bucket was recovered from a river in Lancaster, Pennsylvania.
Inside the metal bucket was a smaller, white plastic bucket containing a human skull partially embedded in a gray plastic material.
The recovered objects were taken to the local medical examiner to have the skull removed from the plastic matrix and to be analyzed.
The medical examiner found the plastic to be very difficult to remove, to the extent that the motor on a bone saw burned out in an attempt to extract the skull.
The skull and plastic were then sent to the FBI Laboratory to determine the composition of the matrix and to attempt to extricate and analyze the human remains.
Radiographs revealed a skull with the cranium and mandible disarticulated within the plastic matrix (Figure 1).