Fossil Crinoids

July 5 (Tuesday), 6 p.m., Teton Co. Library Auditorium – Open to Public. Presentation: “Fossil crinoids from the ancient oceans of the Tetons”. Presented by Forest Gahn, BYU Idaho.


About 350 million years before the formation of the Tetons, Jackson Hole and the surrounding region were situated approximately 10 degrees north of the equator and were part of an ancient ocean basin. Myriad marine animals, including corals, brachiopods, trilobites, and crinoids lived and died in this environment. Catastrophic submarine landslides (turbidites) occasionally buried many of these organisms alive, preserving snapshots of the ancient seafloor communities. Later, these sediments formed rocks that were uplifted and exposed in local mountain ranges, including the Tetons. As a result, many of the surrounding mountains include abundant marine fossils.

Among the most diverse and beautiful of these fossils are crinoids, a group of stalked echinoderms related to starfish and sea urchins. Crinoids, commonly known as sea lilies and feather stars, originated about 500 million years ago and still live in the ocean today. Although they look like plants, crinoid are animals that mostly live attached to the seafloor and filter seawater for plankton with feathery arms. Locally, hundreds of fossil crinoids can be found intertwined on some limestone surfaces, and they are so well preserved that these fossils can be studied almost as if they were from living biological assemblages. In addition to revealing patterns of original diversity and relative abundances, crinoids from the Tetons reveal evidence of ancient biotic interactions, including predation and parasitism.

This presentation will showcase local crinoids and their collection, in addition to active research on their preservation and paleoecology.