Originally discovered in Kansas, which was once an inland sea that spanned North America, Xiphactinus was a long, ray-finned fish that was built for speed and living like today's tuna or tarpon, even greatly resembling the latter, which have been clocked at over 30 miles an hour. Having a generalist diet, feeding on anything it could fit in its enormous maw, occasionally swallowing and choking on fish almost its own length, around 20 feet in length. They had a very successful lifestyle with fossils being found globally, terrorizing both the coast and the open ocean; they survived right up until the KT extinction event.

https://youtu.be/wV2CF2WWGFQ