The study of gravity currents has long been of interest due to their prevalence in industry and in nature, one such example being the spreading of viscoplastic (yield-stress) fluid films. When a viscoplastic fluid is extruded onto a flat plate, the resulting gravity current expands axisymmetrically when the surface is dry and rough. For such a case, the flow above the non-slip surface is dominated by shear stresses. However, when experiments are performed with a viscoplastic fluid (Carbopol) extruded onto a flat plate wet by a thin coating of water, fractures appear to create a distinctive flower-like pattern. By performing a number of variations on the experiments, we demonstrate that a recently proposed shear-thinning extensional-flow instability is not responsible. Instead, further investigation suggests that these patterns arise from the solid-mechanical fracturing of the complex fluid, exacerbated by the presence at the surface of the solvent making up the fluid (i.e. water) which reduces the fracture toughness.