Although crinoids look more like delicate lilies (crinoid comes from krínon--the Greek word for “lily”), they actually are related to starfish, sand dollars and sea urchins. Fossil Jimbacrinus crinoids from Australia are very rare to come by, and this plate with over a dozen 3D specimens--including a straight cephalopod--is even more so. Crinoids are an excellent example of a living fossil because there are over 600 species of crinoids with us today with very little evolutionary differences.
The first true Crinoids first appeared during the Ordovican period almost 490 million years ago making it the earliest echinoderm. Mass mortality fossils of Jimbacrinus crinoids show that these sea creatures lived in large colonies on the shallow ocean bottom around western Australia where some present-day species can still be found.
Jimbacrinus had five flexible arms attached to the cup-shaped calyx, giving them their “flower” appearance. These appendages had a special feathery lining, called pinnules, and sensitive tube feet. When the arms uncurled to catch food particles the pinnules would help to move the catch to the mouth. The mouth and anus of the crinoid were located within the calyx. The hollow, yet supple segmented stem contained the nervous system and the holdfast, or roots, held the animal to the seafloor (some crinoids are able to choose where to root, some float, and others are able to walk). Jimbacrinus grew to about nine inches in length. The largest known crinoid fossil had a stem almost 130 feet long.
Fossil coprolite from fish and other cephalopods have been discovered with crinoid body parts like calyxes and torn off stems suggesting these ancient bottom dwellers had several predators.
This large plate displays over 20 different crinoid specimens from the Late Permian period around 260 million years ago. It is 17” x 15” and the longest stem measures six inches long. The five-inch straight cephalopod can be seen in the lower left. Sections of stems and inadunate crinoids where the arms are detached from the calyx are present. The incredible preservation and preparation of these creatures give them a graceful alien-like appearance.
Jimbacrinus bostocki Teichert 1954
Late Permian, Artinsk.
*note Conularid association
Northwest Basin, Western Australia