I was invited to lead a couple of mt. dulcimer jams at the Will McLean Music Festival (March 11-13, Sertoma Youth Ranch, Brooksville, FL). A couple of the gals from the New River Strings group and I wandered through the vendors where I found this wonderful fossil — I’ve always wanted a specimen from the Green River! The vendor said he’d been carting it around for years and so let me have it for a pittance.
Online: This site from Berkley —
http://www.ucmp.berkeley.edu/tertiary/eoc/greenriver.html — gave me some excellent information which I share here along with a photograph of the latest acquisition to my at-home museum.
For those of my more scientifically minded friends … oh, wait, that’s all of my friends … the fish are lower left: a herring, Knightia alta and the fish on the upper right is Diplomystus dentatus. Both are among the most common fossil fish found in the Green River formation. They’re estimated to have been deposited during the early to middle Eocene between 49.7 and 50.7 million years ago. (You can see why I’m excited about this beautiful fossil!)
The following is slightly altered from the information at the Berkley page: “One of the most important fossil sites for understanding the Eocene is found at Green River, located in western Colorado, eastern Utah and southwestern Wyoming in the United States. During the Eocene, this region was located at much the same latitude it is today, though the climate in which the organisms lived differs somewhat from that of the present-day western United States. The fossils, especially plants, found at this site indicate that the climate was moist temperate or sub-tropical, with temperatures ranging from 15 to 20 degrees Celsius. In addition to the plants, another piece of evidence suggesting that the climate was sub-tropical was the presence of fossilized crocodiles. Crocodiles can only survive in areas with a constant, warm temperature.
If you were able to visit the Green River locality during the Eocene, you would see palms, cat-tails, sycamores, and other familiar plants from North America, but you would also see some that are today more common in, or restricted to, eastern Asia. A series of large inland lakes extended across the region, and it is in the bottoms of these lakes that various plants and animals were buried and fossilized. These lakes later dried up as the local climate changed, and many of the plants and animals living here went extinct.”
Unfortunately I never got to go to the Green River when I lived out west. None of the people I knew in Colorado were into fossils (except Norma and Lauri Noble, both geologists) and I did most of my digging alone.