The single factor that has made Fossil Butte world famous is the
occurrence of literally millions of beautifully preserved fossil fish.
In one layer approximately 14 inches thick, the fish are nearly black
and preserved in a nearly white shale. Most of the fish are perfectly
preserved, retaining every detail of the skeleton and even undisturbed
scales. Fish from Fossil Butte have been collected and sold since the
1870s and may be found on sales counters, in museums, and on living room
walls throughout the world.
The fossil fish from the Green River Formation have a history of
discovery stretching back to 1856. At that time Leidy (1856:256)
described a fish given to him by a Dr. John Evans. Leidy called the fish
_Clupea humilis_, a type of herring. Exactly where Dr. Evans obtained
the specimen is not known. He passed through the area of the Green River
Formation several times and could have collected it during any one of
those trips (Knight 1955:12).
During the construction of the Union Pacific Railroad in the 1860s,
workmen blasting a cut through Green River shales, about 2 miles west of
Green River, Wyoming, came upon remains of well-preserved fish. Hayden
(1871:742) first mentions this cut as "Petrified Fish Cut." Many of the
fish from this cut were given to Cope who described them in Hayden’s
(1871) report. Insects, plants, and a bird feather were also obtained
from "Petrified Fish Cut" at this time.
Sometime in the 1870s the first fish were obtained from Fossil Butte
itself. Cope (1877, 1878) described fish from the Green River Formation
which may be from Fossil Butte. His locality is "nearer the mainline of
Wasatch Mountains" (Cope 1877:807). This may be Fossil Butte. His 1878
locality information is just as poor. He does mention a specimen of
_Priscacara peali_ given to him by A. C. Peale. Since it was Peale who
first wrote about Fossil Butte, the specimen may have come from the
butte.
Peale (1879) first mentioned the quarrying of fish at Fossil Butte, but
he had no specific date as to the discovery of the butte or the
beginning of quarrying of fish.
Cope (1884) published two large volumes about the Tertiary vertebrates
of the West. Here he mentioned three fossil localities for his Green
River Fish: "Petrified Fish Cut," "The Mouth of Labarge Creek," and
"Twin Creek." Twin Creek is now known as the Fossil Butte site.
Since that time, the quarries at Fossil Butte have been extensively
worked, mostly by commercial collectors.
The fish from Fossil Butte form an unusual array of genera (Table 1)
unlike any now found living together. Included in the assemblage are
forms usually found in marine waters and tropical, fresh-water fish
(Schaeffer and Mangus 1965).