 Sea eagles and other fish-eating birds of prey are also typically excluded, however tied to marine environments they may be.Seabirds, by virtue of living in a geologically depositional environment (that is, in the sea where sediments are readily laid down), are well represented in the fossil record.They are first known to occur in the Cretaceous period, the earliest being the Hesperornithiformes, like "Hesperornis regalis", a flightless loon-like seabird that could dive in a fashion similar to grebes and loons (using its feet to move underwater) but had a beak filled with sharp teeth.