Natural History - Flexicalymene Fossil Trilobite Nodule

Displaying serrations and polished enamel, from the Carcharocles megalodon shark. 238 grams, 10.5 cm



Ex Lincolnshire, UK, collection.

Carcharodon megalodon is regarded as one of the largest and most powerful marine predators in vertebrate history and likely had a profound impact on structuring of the marine communities. Fossil remains indicate that this giant shark reached a length of more than 16 metres (52 ft) and also affirm that it had a cosmopolitan distribution. Scientists suggest that C. megalodon in life looked like a stockier version of the great white shark, Carcharodon carcharias.

On a rectangular matrix. 292 grams, 15.7 cm



From Wyoming (Green River Formation), USA. From an old Bristol, UK, collection.

Seasonally some 58 million years ago, in the Green River region of Wyoming, torrential rains fell in the mountains. They flowed down the mountain sides, forming wide shallow lakes in the valley below. During the dry season, these lakes would dry up due to evaporation (as happens in 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 entombed all these fish. At a much later date, volcanic activity uplifted this area to expose the fossils.

A polished blue banded agate book end pair, showing some exposed crystals. 4.6 kg total, 13.5-14.5 cm



From a Humberside, UK, collection.