"Tylosaurus" likely specialized as an ambush predator. It was lightweight for a mosasaur of its size, having a morphological build designed to vastly reduce body mass and density. Its pectoral and pelvic girdles and paddles, which are associated with weight, are proportionally small. Its bones were highly cancellous and were likely filled with fat cells in life, which also increased buoyancy. It is unlikely that the latter trait was evolved in response to increasing body size as the similarly-sized "Mosasaurus hoffmannii" lacked highly cancellous bone. These traits allowed "Tylosaurus" to be more conservative in its energy requirements, which is useful when traveling between ambush sites over large distances or through stealth. In addition, a reduced body density likely helped "Tylosaurus" to rapidly accelerate during an attack, assisted with the long and powerful tail of the mosasaur.