Rare and interesting fossils...

The fossils are shown in order of increasing age:

Botfly Larvae from the Green River (Oil) Shale of Wyoming, from the Eocene. These provide a good example of soft tissue fossilization, in rocks more than 50 million years old! The Green River formation is made up of layers, mostly paper-thin, which seem to represent depositions of one year at a time. The fact that there are millions of layers gives a clue to how long it took to lay down this layer of shale.

This is a marine worm from the Silurian, another "soft" fossil. It comes from the Racine formation, specifically a canal in Blue Island, IL.

This is another Silurian fossil, from Bulgaria, a graptolite, Spirigraptus spiralis.

This is from the Harding Sandstone of Colorado, Middle Ordovician. These are phosphoric plates from the armor of one of the earliest vertebrate fishes, possibly Skiichthys? These denticles are complex and beautiful under magnification. Here they are shown four times actual size.

An early Crinoid from the Spence Shale, in the Middle Cambrian. This is ten times older than the Eocene example at the top of the page. The Spence Shale is in northern Utah and southern Idaho.

This is probably Yuknessia, a kind of algae which is found in the Lower Cambrian fossils of Chengjiang and the Ruin Wash site. These fossils are older than the Burgess Shale fossils. Ruin Wash is near Pioche, Nevada.