
The Properties of Fossil Cephalopod Shells
Among the 800+ species of modern cephalopods, only the five Nautilus species have external shells. But, in the distant geological past, most cephalopods had heavy, large, chambered shells that, like the Nautilus shells, allowed them to regulate their buoyancy and orientation in the water. David J. Peterman of Wright State University and his collaborators recently published a comprehensive article in Palaeontologia Electronica suggesting that distinct groups of long-extinct cephalopods differed