A Revision of our Knowledge of African Elephants' Teeth, with notes on Forest and “Pygmy” Elephants.

Abstract

Summary. The problem is to decide, given an African elephant's tooth, the position of that tooth in the series of six. This has been done hitherto by reference to the “ridge formula” whose origin is discussed, and which is shown (a) to have been commonly misinterpreted, and (b) to have been inaccurate in any case. The misleading results, including alleged evidence in support of the existence of a “pygmy” elephant, which resulted from this, are discussed. It has been found impossible to construct a ridge formula which would be of any use in the determination of the position of a tooth in the series and other methods are proposed including the use of two new indices—the laminary index and the enamel‐loop index. The conclusion is arrived at that teeth numbers I and II may always be identified with certainty, number III with fair certainty, and number VI with much less certainty. Numbers IV and V are not at all easily to be distinguished.

Qualitative Comparison of the Cranio‐Dental Osteology of the Extant Elephants,Elephas Maximus(Asian Elephant) andLoxodonta africana(African Elephant)

“…There has been much controversy over whether this subspecies should actually be a separate species from the savanna elephant (Matschie, 1900; Greenwell, 1992). The most striking difference is in overall body size, with males averaging 2.3 m at the shoulder and females averaging 2 m (Morrison‐Scott, 1947).…”

The African elephant, Loxodonta africana: a field method for the estimation of age

“…These were macerated and dried, and placed in a line in apparent age order on a long bench. Any preserved developing molars were returned to their respective mandibles and attempts to finalize the sequence by combining laminary counts, measurements of grinding length, enamel loop width, and the calculation of laminary indices were made, using the methods summarized by Morrison-Scott (1947). When the results of this process were used in conjunction both with the broad trends obtained from body measurements and with field notes on the herd-status in life of each specimen, considerable confusion resulted.…”

“…Particular attention was also paid to the preservation and examination of the proximal molars developing within the alveolar pockets. Morrison-Scott (1938, 1947, after the painstaking examination of a vast amount of material, listed 11 different approaches to the measurements and indices that may be used in identifying and ageing a given molar, and described the "ridge formula", concluding that a reliable ridge formula could not, in fact, be constructed. We proposed the "laminary index" and "enamel loop index" as useful methods, but was inconclusive as to a really reliable formula for the identification of any but the first two molars of each half-jaw.…”

African elephant age determination from teeth: validation from known individuals

“…The rate of formation and emergence of a single set of permanent teeth cannot match the growth rate of jaws or bodies, but a sequence of successively larger teeth increases the shearing area available and thus food intake rates keep pace with growth (Maglio, 1973). Owing to this sequential emergence and replacement of teeth, the size, structure and wear of teeth have been used widely as determinants of age with the assumption of strong genetic (rather than environmental) control on the rate of formation and movement in the jaw (Morrison‐Scott, 1947; Laws, 1966; Sikes, 1971; Fatti et al. , 1980; Haynes, 1991; Todd, 2010a).…”