A specimen ofBuchiceras bilobatumis shown to have been able to maintain neutral buoyancy in water despite the ever increasing weight of epifaunal oysters which it carried on its shell. It is deduced that before settlement of the oyster spat, the camerae of the ammonite contained several grammes of water and that this was slowly pumped out as the oysters grew. Revised calculations on the densities of other ammonoids suggest that the presence of large quantities of liquid in cephalopod camerae was a common occurrence. The significance of this liquid in the growth, mode of life, and evolution of ammonoids is discussed.
展开▼
