Stop+5+Fossils+in+the+Steps+of+F.J.+Toole



=Crinoid Ossicles= Grey rock slabs on the walls outside the western entrance to F.J.Toole Hall (Chemistry). They are visible on the cedar planters in the centre of the north face of the building, especially towards the back of the upper surface of the planters.

The grey steps and the ‘fractured’ rocks on the walls either side of the steps contain small fossils. These are the fragmented remains of a sea creature called a crinoid. It was anchored to the seabed, had a long stem, and a head (calyx) with tentacles that caught suspended organic material for nutrition (see Figure). As is the case for many animals, when they die, their bodies disintegrate. The stem breaks into tiny plates, called ossicles. These can be many shapes, depending on the species of crinoid.

In this rock the ossicles are only about 3.5 – 5 mm in diameter, and are lighter in colour than the surrounding rock. They typically have a hole in them, which can also be different shapes, and probably contained a primitive central nervous system (akin to a spinal cord).


 * EXERCISE:** Which of the following shaped ossicles most closely resembles those seen in the rock at this stop?