The side view of a Trimerus delphinocephalus found in Clark County, Indiana in the Waldron Shale layer. The creature lived in the Silurian ...

Here is the back thorax of a Trimerus type trilobite from the Silurian period. It is described in more detail on page 98 of the Fossils of...

Here is a Ordovician bryozoan found in the Kope Formation in Carroll County, Kentucky. It has linear tubes attached, three are showing in t...