Natural History - Amethyst Crystal Geode Section

Knightia alta specimen on a rectangular matrix. 1.03 kg, 19.8 cm



From Wyoming (Green River Formation), USA. From a Lincolnshire, UK, collection.

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.

A near complete Charonosaurus sp. hadrosaur egg, retaining the leathery surface, and possibly showing the internal remains at one corner. 1.73 kg, 14.1 cm



From Xixia Basin, Henan Province, China. Ex Eons Ago, USA, circa 2008. Prepared by Christine Coyle, U.S.A. From the private collection of Mr A Hills, Kent, UK.

Dinosaur eggs are known from about 200 sites around the world, the majority in Asia and mostly in terrestrial (non-marine) rocks of the Cretaceous Period. It may be that thick calcite eggshells evolved during the Cretaceous (145 to 65 million years ago). Most dinosaur eggs have one of two forms of eggshell that are distinct from the shells of related modern animal groups, such as turtles or birds; however, some eggs closely resemble the type of shells seen in present day ostrich eggs.

Ophiuroidea sp. specimen on irregular matrix. 698 grams, 15.5 cm



From El Kaid Errami, Tafilalt, Morocco, North Africa. Acquired 1950s-1960s. From an old Bristol, UK, palaeontological collection.