Figure 2. Impact geometries (1-3) and tail reconstruction of Kentrosaurus aethiopicus Hennig, 1915 (4). 1. penetrating impact, 2. slashing impact, 3. blunt impact. Arrow = direction of travel of spike at impact, β = angle between long axes of spike and tail, β = angle between long axis of spike andsurface of target (long axis of target used as proxy), β = angle between direction of travel of spike and surface of target (long axis of target used as proxy). Note how large values for β are required for a penetrating impact, because the direction of travel of the spike is generally limited to a circle around the tail base. Small values for β make blunt impacts likely. 4. likely distribution and orientation of tail spikes (high resolution laser scan digital 3D files of MB.R.4836- 4843, from left to right), based on description and figures in Hennig (1925). Light grey bones are digital mirror images of contralateral side. Tail modeled as truncated cone over high resolution laser scan digital 3D files of MB.R.4800.6 (caudal 1 of lectotype) and MB.R.4801-6 (coossified tail tip vertebrae). All fossils from quarry 'St', Tendaguru, Tanzania, all spikes not part of lectotype and not found in association.