Oceans of Kansas: A Natural History of the Western Interior Sea

The bright midday sun glinted off the calm waters of the Inland Sea and silhouetted the long, sinuous form of a huge mosasaur lying motionless amid the floating tangle of yellow-green seaweed. Twenty years old and more than thirty feet in length, the adult mosasaur was almost full-grown and was much larger than any of the fish or sharks that lived in the shallow seaway. A swift and powerful swimmer over short distances, the mosasaur used surprise and the thrust of his muscular tail to outrun his prey with a short burst of speed. --from Chapter One