A new method of age determination for mammals

For estimating the age of mammals such widely differing characters as coat colour, size, skull proportions and sutures, ossification, numbers of corpora albicantes, changes in the lens of the eye, etc., have been used; but such methods are laborious and frequently yield only an approximate result. While working on the elephant seal (Mirounga leonina) in 1949, a new and accurate method of determining age, depending upon cyclical variation in the rate and manner of calcification of the teeth, was developed. This makes possible determination of age, to within a month, up to at least twenty years in the male, and thirteen years in the female.