Best fossil collecting is in an inner-bedded shale-limestone, and is Upper Mississippian age. I looked for blastoids, crinoid stems and heads, horn corals, archimedes remains, brachiopods, trilobites, sharks teeth and scales in these shale beds. Most of the collecting here requires some climbing so I put my tools in a backpack and headed up the cut to a promising place. I noticed that the fine bedded darker layers had been where others have been digging so I concentrated my efforts here. Please note we made sure to keep our car well off the right-a-way of the highways.

Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm. Often called sea buds, blastoid fossils look like small hickory nuts. They originated, along with many other echinoderm classes, in the Ordovician period and reached their greatest diversity in the Mississippian epoch (where I was hunting) of the Carboniferous period. Blastoids thrived until their extinction at the end of Permian, about 250 million years ago. Although not as diverse as the crinoids, blastoids are quite nice fossils, especially in many Mississippian-age rocks. They can be found in Illinois, Kentucky, and Indiana.

Like most echinoderms, blastoids were protected by a set of interlocking plates of calcium carbonate, which formed the main body. In life, the body of a typical blastoid was attached to a stalk or column made up of stacked disc-shaped plates. The other end of the column was attached to the ocean floor, very much like crinoids. The mouth was located at the top of the stalk. Radiating like flower petals from the center were five food grooves. Each food groove had many long, thin, fine structures called brachioles, which were used to trap food particles and bring them to the mouth. This gives the Blastoids a unique appearance.

matrix pieces with blastoids showing

close up of blastoid in matrix

close up of 1/2 inch blastoid in matrix"

horn corals oyster shells and crinoid stems

lot of blastoid heads

close up of blastoids

several different kinds of blastoids, smaller sizes

large blastoid head shown from top.

Like crinoids, blastoids were high-level, stalked suspension feeders, feeding mainly on planktonic animals that inhabited clear and silty ocean waters from shelf to bottom.

I found around 75 different blastoid heads as well as quite a few horn corals, oyster shells, and crinoid stems in a matter of 2 hours at this site.

I hope you enjoyed the Field Trip Report!

till next time

KOR

Everett