As you embark on your journey to explore the Ozarks, stop to smell the roses, so to speak. Breathe the crisp clean air into your lungs and notice the vast array of trees towering above. In spring beautiful dogwoods bud with brilliant white flowers. Animals, like chipmunks, foxes, and deer frolic through the wilderness. In the fall the leaves on the trees turn a stunning red, gold and purple. A sight you must see only in person to understand its awesomeness. In the distance a ravine cut by erosion and time runs through the Park. Millions of years ago if you were here you would be under water. Today you will find evidence of ancient times, treasures left for eternity untouched by Mother Nature, in countless fossils.
Meriam-Webster defines a fossil as, "a remnant, impression, or trace of an organism of past geologic ages that has been preserved in the earth crust." There are many different types of fossils that come from both plants and animals. Fossils are formed by a process called petrification. This is where a plant or animal will die and the remains are covered by mud and silt, preserving it. Fossils can be from plants or animals. Sometimes in fossils the actual structure of soft tissue or bone can decay completely away over time, leaving only an impression. Other times in animal fossils, bones themselves may actually become preserved.
450 million years ago, during the Paleozoic Era, for much of the time, Arkansas was covered by ocean. Here in Northern Arkansas, the ocean was shallow, and marine plant and animal organisms thrived greatly. Throughout the Paleozoic Era, the geology of Arkansas started to change drastically. Through the processes of continental drift and the moving of tectonic plates, occasionally the water level would rise and then subside again, causing erosion. These processes brought in silt and mud to northern Arkansas and created just the right environment for fossils to begin forming. "Calcium shells and skeletons became limestone, sand became sand stone, silt became silt stone, and clay became shale." (Foti, Thomas: Encyclopedia of Arkansas). At the end of the Paleozoic Era, marking the beginning of the Mesozoic Era, Arkansas became dry and the marine life that once thrived started to become extinct. One such animal was various crinoid species.
Crinoids are called sea lilies because they resemble an underwater flower. Even though crinoids resemble a flower, they are not plants. Some people will mistake a crinoid for a plant because of common features. The calyx or head of the crinoid can be mistaken for the sepals of a flower. The arms of a crinoid resemble the petals of a plant. Lastly, the columns of a stalked crinoid resemble that of a stalk on a plant. The columns of crinoids can be many feet in length which attach to the ocean floor.
(Click here to see Crawling Crinoid video)
Even though similar on the outside, inside crinoids differ greatly from plants. In fact they are actually marine animals with a nervous system, a digestive system, and reproductive systems. Also crinoids do not use photosynthesis to survive. They actually eat plankton floating around in the ocean. The amount of crinoids that existed at the time was immeasurable. Vast forests of crinoids could be found in the shallow ocean waters which made Northern Arkansas a hot spot for crinoids during the Paleozoice Era. In fact, the abundance of crinoids was so great that in certain places you could find whole beds of limestone that were made of just crinoid body parts. Of the crinoid fossils that can be found, most are stalk fragments.
(Click here to see Introduction to Fossil Crinoids Part 1 video)
Even though prehistoric crinoids are gone today, types of crinoids can still be found. They are not the same species though. Living crinoids and their closest living relatives, which include starfish, sea urchins, and sand dollars, are usually found in deeper ocean water.
To receive credit for this earthcache, the following are required for approval:
1. Post a picture of yourself at the "Giant Alien Monkey Skull" (optional)
2. What shapes are the crinoid fossils (e.g., circular, tubular)?
3. Facing the "Giant Alien Monkey Skull," how many segments does the crinoid fossil have on the top left side?
4. How many centimeters, approximately, is this crinoid fossil?
5. How many fossils, approximately, are on the "Giant Alien Monkey Skull?"
6. Is the crinoid fossil a plant or an animal fossil?
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1. Kammer, Thomas W., Lane, Gary. "Crinoids Paleontological Society." www.paleosoc.org/crinoids.pdf. Geological Society of America and the University of Kansas. Pub. 1978. Web. 21 November 2014.
2. Mann, Doug & Claudia. "Crinoids Past Meets Present." http://www.fossils-facts-and-finds.com/crinoids.html. Published by fossils-fact-and-find.com. p. 2013. Web. 21 November 2014.
3. Guccione, M.J. "Geologic History of Arkansas Through Time and Space." http://ebookbrowseee.com/geologic-history-of-arkansas-through-time-and-space-color-copy-pdf-d76644873. National Science Foundation. Margaret J. Guccione. P. 1993. Web. 21 November 2014.
4. Foti, Thomas. "Geologic History: Arkansas in the Paleozoic Era." http://www.encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?search=1&entryID=401. Department of Arkansas Heritage. University of Arkansas Press. P.1992. Web. 21 November 2014.
5. Hamilton, Calvin and Rosanna. "The Formation of Fossils." http://www.scienceviews.com/dinosaurs/fossilformation.html. ScienceViews.com. p. 2003. Web. 21 November 2014.
6. "fossil." Merriam-Webster.com Merriam-Webster, 2011. http://www.merriam-webster.com/dictionary/fossil. Web. 11 November 2014.