Max Garcia, “Physically Testing the Tully Monster’s Hydrodynamics”
Mentor: Victoria McCoy, Geosciences
Poster #203

Tullimonstrum gregarium, commonly known as the Tully Monster, is a large soft-bodied extinct fish known only from the Late Carboniferous Mazon Creek fossil site located in Illinois, USA. The Mazon Creek fossil site is renowned for its more than 2 million well-preserved fossils found inside ironstone concretions including more than 2,500 Tully Monster specimens. The Tully Monster is an odd critter that greatly lacks the swimming features of other organisms. With no paired fins, an eyebar stretching perpendicular from the midline of the body, and a long proboscis for a mouth, the Tully Monster has a very unusual body plan. These amazingly preserved specimens have led to dedicated research and analysis of the Tully Monster, to answer the question “how did it swim with such a peculiar body plan?”. To understand the hydrodynamics of the Tully Monster, we printed a 3D-model of the organism and placed him inside of a flume, a large tank of flowing water designed to replicate ambient flow while swimming, tied to a rock and a platform for stabilization, and observed the way particles moved around its body to visualize flow. We found that the eyebar stabilized the body during swimming, and the proboscis was used for turning by deflecting water around the body. Further analysis of these findings will provide more understanding of the ecology of the Tully Monster and how it would fit into the unique ecosystem of its time.