The extinct giant white shark, Carcharondon megalodon , swam in these waters, as evidenced by the occassional discovery of a fossil shark tooth that is roughly the size of the palm of a human hand. Marine specimens are diverse. Microfossils of foraminifera and diatoms are abundant. Echinoderms, barnacles, crabs, crocodiles' teeth, and sea turtles have all been preserved here. Fossil remains of birds such as the booby and the gannet have been found.
Terrestrial animals are present in the fossil record also.
Bones from mastadons and rhinoceros are among the fossil treasures of these sediments as are those of tapirs, horses, and tortoises. The formations of the Chesapeake Group provide a rich record of life in and along the shores of the Salisbury Embayment during the Miocene. The exposure site is known as the Horsehead Cliffs. The sedimentary record is incomplete here. The oldest sediments are from the Calvert Beach Member of the Calvert Formation.