Check the listing for details. 8 Calvert Cliffs MD Miocene Fossils Whale Dolphin Bones Barnacle Bivalve Turtle. Condition: Used. Listed at 59.99 USD. 8 Calvert Cliffs MD Miocene Fossils Whale Dolphin Bones Barnacle Bivalve Turtle. Fossiized shells and bones from the Calvert Formation site in Maryland. Dated to the Early to Middle Miocene era (23-15 million years ago). Very nice examples. Includes: fossil cast cluster, Glycymeris sp blivalve (whole shell filled with mud), barnacle clump, black bone (dophin or whale), dolphin rib fragment, spinous process or fin bone, turtle shell fragment, small bone fragment. Adapted from online sources: In the early to middle Miocene, the Salisbury Embayment was a shallow sea (Delaware, Maryland, and Virginia coastal plains). It is thought to have been a calving ground for many species of early dolphins and whales. Since there were so many marine mammals here, the largest of prehistoric sharks, the Megatooth sharks, spent time feeding here. The fossil bearing Calvert Cliffs of Maryland is part of a large collection of fossiliferous exposures, called the Chesapeake Group. The Chesapeake Group encompasses exposures around the Chesapeake Bay, D.C., Maryland, and Virginia. #2