Swimming Ability of the Enigmatic Carboniferous Fish: Tullimonstrum Gregarium

Abstract

Tullimonstrum gregarium, more commonly known as the Tully Monster, is one of the strangest creatures in the fossil record. While it was traditionally considered a problematic fossil, recent studies have firmly placed the Tully Monster with the vertebrates as a relative of lamprey and hagfish. This may offer insight into the Tully Monster’s ecology, but the Tully Monster’s Swimming ability remains uncertain due to its strange body plan. This study aims to investigate the hydrodynamics of these features to gain insight into the Tully Monster’s swimming ability using computational fluid dynamics (CFD). 3D and 2D simulations of the Tully Monster revealed that the eyebar and proboscis are likely key hydrodynamic features, and that the tail fin complex could have generated pressure differentials. Pressures generated around the body also suggest the Tully Monster was a slow swimmer, and likely had a hydrodynamic tendency to descend in the water column.