by Tiffany Adrain, Paleontology Repository, Department of Earth and Environmental Sciences, University of Iowa, Iowa City, Iowa
This summer, the University of Iowa’s Mobile Museum is rolling out across the state of Iowa with a brand new Museum icon aboard – “Scorpy,” Iowa’s Giant Sea Scorpion! The 6-foot-long, life-size model of the recently discovered and described new species of Ordovician eurypterid (sea scorpion), Pentecopterus decorahensis, is the star of the exhibit, “Delving Deep: Scientific Discoveries from Iowa’s Ancient Sea.”
The University of Iowa Mobile Museum launched in 2014 as a partnership between the Office of the Vice President for Research and Economic Development, the Office of the State Archaeologist, and the Pentacrest Museums. It inspires visitors to understand the world by bringing exhibits with cutting-edge research, one-of-a-kind artifacts, and interactive digital media to Iowa’s communities statewide. It promotes interdisciplinary partnerships and collaborations to present UI research and stimulate understanding, appreciation, and pride for the University of Iowa and the state.
The “Delving Deep” exhibit tells the amazing story of the discovery of an Ordovician sea scorpion, the world’s oldest and the largest for its time, and its surprise association with a meteorite impact crater. In 2005, the Iowa Geological Survey (IGS) discovered a shale outcrop in Decorah, Iowa, with the help of a local geologist, as part of their state bedrock-mapping program. They had been looking for rocks that matched an historic account of a shale that was so rich in organic material that it could be burned like coal, which the locals of the time believed (and hoped) it was. The shale was inconveniently submerged in the river on the outskirts of Decorah, but when one of the geologists fell in after peering too closely, he managed to collect some good samples. Later, with the help of funding from the National Science Foundation, a part of the riverbank was dammed temporarily for more intense collecting. UI students spent hundreds of hours over several summers splitting the shale samples, leading to the discovery of unusual fossils, different from those in similar age rocks in the surrounding areas. Other Ordovician formations in Iowa preserve fossils such as gastropods, brachiopods, trilobites, crinoids, cephalopods, algae and other common bottom-dwelling organisms. In contrast, the shale contained an entirely different suite of fossils: conodonts (microscopic jaw parts) still associated with the conodont animal, shrimp-like phyllocarids, coprolites, early jawless fish, algae, and large pieces of organic cuticle from the oldest known eurypterid. This 465-million-year-old fauna is so unusual, rare, and well preserved, it was given the name of the Winneshiek Lagerstätte. The eurypterid remains were studied by James Lamsdell, Postdoctoral Associate at Yale University, who described them as a new species; Pentecopterus decorahensis – a penteconter is a Greek warship, and –pterus means “wing,” Decorah is the town where the discovery occurred (Lamsdell et al. 2015).
Making an Impact
The research did not stop there! The question remained about why this shale with its special fossils was there in the first place. The IGS and the U.S. Geological Survey investigated, taking rock cores, and using aerial geophysical surveying. They discovered that the shale unit was present in a 3.5 mile–wide circular area, surrounded by deformed rocks and underlain by a breccia of angular broken rocks. The presence of shocked quartz was the final clue that the Winneshiek Lagerstätte sits in a meteorite impact structure! This is only the second impact structure discovered in Iowa (the Manson Impact Structure is the only other one known). The crater left in the Ordovician sea-floor by the meteorite impact provided a deeper, quieter environment unsuitable for common Ordovician organisms, but perfect for the undisturbed preservation of giant sea scorpion molts.
Scorpy on TV!
When James Lamsdell and his co-authors published their paper about the new sea scorpion, National Geographic got interested and included the story in their TV show The Strange Truth. I was lucky enough to be invited to participate as Collections Manager of the University of Iowa Paleontology Repository, Iowa City, where the Winneshiek Lagerstätte specimens are housed. Very early, one cold November morning, I headed off to Decorah with IGS geologist Paul Liu to meet his colleague Bob McKay and be interviewed for the show. I was quite excited but also terrified! The film crew was great (and very good at editing, thankfully)! After we did our serious-scientific-interviews-in-a-darkened-room, we had a bit of fun in store for the town of Decorah – Scorpy’s homecoming! Dennis Wilson of Pangaea Designs in Denver had been commissioned to make a life-size model of the sea scorpion and brought it to Decorah for its debut! And so, for one afternoon and morning, after a chilly unveiling at the river bank with the IGS geologists, film crew and the landowners who had permitted the excavations, “Scorpy” (the film-crews’ name for the model) was brought to life and driven around the town of Decorah, visiting the local pizza parlor for eurypterid-shaped pizza, and the local high school for his own personal homecoming! The NatGeo show aired in January 2016 – we’re famous!
On the road again!
Now, for the summer of 2017, Scorpy is back on the road in the UI Mobile Museum, thanks to the generosity of Dennis Wilson, who donated a new model especially for the “Delving Deep” exhibit. In the exhibit, visitors can also see examples of typical Ordovician fossils, replicas of the delicate Winneshiek Lagerstätte fossils, and meteorites from the UI Department of Earth and Environmental Sciences collections. Other exhibits in the UI Mobile Museum are “Speaking of Work: The Iowa Labor History Oral Project” and “Oneota Archaeological Connections.” Two interactive digital touchscreens with several digital exhibits let visitors learn about research and creative activity happening in a variety of UI units. The UI Mobile Museum is available for free to tour schools across Iowa from April through the end of October. A staff of highly experienced educators from the Pentacrest Museums and the Office of the State Archaeologist are collaborating to create associated guidelines and activities to enrich the Mobile Museum experience for students. The UI Mobile Museum is also available for community events. If you are in Iowa this summer, check out the calendar of events at https://discover.research.uiowa.edu/mobile-museum and maybe you’ll get to meet Scorpy!
Lamsdell, J. C., Briggs, D. E. G., Liu, H. P., Witzke, B. J., and McKay, R. M. 2015. The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa. BMC Evolutionary Biology 15:169 DOI: 10.1186/s12862-015-0443-9.