Protoconch size of lepidocyclina (nephrolepidina) - a potential paleoclimatic indicator

Analysis of an Indo-Pacific species, Lepidocyclina (Nephrolepidina) sumatrensis shows that the protoconch diameter varies with latitude. The data plotted on the reconstructed continental positions for the Miocene epoch shows that forms away from the equator are characterised by progressively larger protoconch diameter. An average value of protoconch diameter > 200mu is seen to occur from 15-degrees to 30-degrees latitude while those with < 200mu are confined within 15-degrees latitude. This observation can have potential use in inferring the climate of the geological past