an arc of 180 degrees, covering the entire half circle behind it. Swing speeds at the tail end may have been as high as 50 km/h. Continuous rapid swings would have allowed the spikes to slash open the skin of its attacker or to stab the soft tissues and break the ribs or facial bones. More directed blows would have resulted in the sides of the spikes fracturing even sturdy longbones of the legs by blunt trauma. These attacks would have crippled small and medium-sized theropods and may even have done some damage to large ones. Earlier interpretations of the defensive behaviour of Kentrosaurus included the suggestion that the animal might have charged to the rear, to run through attackers with its spines, in the way of modern porcupines. Though Kentrosaurus likely stood with forelimbs erect like in other dinosaurs, it is hypothesised that the animal adopted a sprawling posture when defending itself. Its neck was flexible enough to allow it to keep sight of predators, as it could reach the sides of its body with its snout and look over the back. In addition, the posterior position of the center of mass may not have been advantageous for rapid locomotion, but meant that the animal could quickly rotate around the hips by pushing sideways with the arms, keeping the tail pointed at the attacker. Kentrosaurus was nevertheless not invulnerable. A quick predator could have made it to the tail base (where the impact speed would be much lower) when the tail passed and the neck and upper-part of the body would have been unprotected by the tail swings. A successful predation of Kentrosaurus may have required group hunting. Compared to the more robust spikes of Stegosaurus, the thinner spikes of Kentrosaurus were at greater risk of bending. Paleoecology Kentrosaurus lived in what is now Tanzania in the Late Jurassic Tendaguru Formation. The main Kentrosaurus quarries were located in the Middle Saurian Beds dating from the upper Kimmeridgian. Some remains were found in the Upper Saurian Beds dating from the Tithonian. Since 2012, the boundary between the Kimmeridgian and Tithonian is dated at 152.1 million year ago. The Tendaguru ecosystem primarily consisted of three types of environment: shallow, lagoon-like marine environments, tidal flats and low coastal environments; and vegetated inland environments. The marine environment existed above the fair weather wave base and behind siliciclastic and ooid barriers. It appeared to