Fossil "Mother Lodes"

The history of life on Earth is a story told in photographs made of stone--the rocks and fossils preserved when and where conditions were favorable. Some of these photos are time exposures in which events blur together, others, much rarer, are snapshots of an instant in time. These snapshots commonly are the result of the sudden, rapid burial of the organisms living in the environment, as through an ocean storm surge or river flood or avalanche or entrapment in a mucky bog or sticky pit of natural asphalt. These snapshots are characterized by exquisite preservation of anatomical details not usually fossilized, and fossil deposits of this sort are referred to by a German word, lagerstatte, which is a mining term that refers to a "mother lode" or abundance of ore. Fossil lagerstatte are "mother lodes" of exceptionally preserved fossils. The Pennsylvanian (320-286 million year old) Mazon Creek fauna, from which the bizarre Tullymonstrum (the state fossil of Illinois, seen here from the side of a U-Haul truck) is known is one example.

This week's GeoLog challenge is to describe the 5 most significant fossil faunas or lagerstaette, fossil "mother lodes." Despite the relative rarity of exceptional preservation, the list of lagerstaette, for example the list posted on the Wikipedia website, takes up a whole page, so some selection criteria need to be imposed. My "top 5" lagerstaette were chosen to include different geological periods, different depositional or geological environments, and a variety of organisms, from microfossils to dinosaurs, and for their historical significance.

Paleontologically, all lagerstaette are important, because we've learned things from each of them about the variety and diversity of life that we would not have known otherwise.