Natural History - Barrandei Fossil Trilobite

In a matrix. 112 grams, 13.2 x 8.5 cm

Fine condition.

From the Green River Formation, Lincoln County, Wyoming, U.S.A. From an old Lincoln collection.

Seasonally, some 56 million years ago, in the Green River Region of Wyoming, torrential rains fell on the mountains. The rain flowed down the mountain sides, forming wide shallow lakes in the valley below. During the dry season, these lakes evaporated (similar to certain parts of Africa today). Millions of fish died in this short period of time. This climatic cycle happened over a 20-thousand-year period. Layer upon layer of mud was deposited over these years, entombing huge numbers of fish. At a much later date volcanic activity uplifted this area to expose their fossils.

Displaying a fossil Knightia sp. fish. 553 grams, 15 cm



Acquired during the 1980s. From the Pradi Collection, Boston, U.S.A.

In southwest Wyoming (and parts of Colorado and Utah) in the Green River Formation are found some of the world's most outstanding specimens of fossil fish. The Green River system was composed of three lakes: Lake Ulinta, Lake Gosiute and Fossil Lake. These Eocene lakes lay in a series of intermountain basins formed by geological events that uplifted the Rocky Mountains during the early Tertiary time. The climate was much different from the desert-like climate of this area today. Both the fauna (crocodiles, alligators, boa constrictors and some subtropical fish families) and the flora (such as large palm trees) indicate a climate much like that found along the Gulf Coast today. Large amounts of ash found in the sediments indicate that volcanoes were particularly active at this time.

Comprising three Ophiuroidea sp. specimens on matrices. 330 grams total, 9.1-11.4 cm



From El Kaid Errami, Tafilalt, Morocco, North Africa. From an old German collection.