. Bulletin of the British Museum (Natural History), Geology. FOSSIL ANTILOPINI OF EAST AFRICA 53 structure throughout its history. However some evolutionary changes do occur, for instance : diminution of the basal pillars (in early gazelles these lie between the anterior and posterior lobes of the molar teeth on the inner side of the uppers and the outer side of the lowers), increasing hypsodonty, and an increasing depth of the mandibular ramus to house the longer teeth. The reason for the decline of the basal pillars (they may be retained in other groups such as the Reduncini and Bovini) is n
. Bulletin of the British Museum (Natural History), Geology. FOSSIL ANTILOPINI OF EAST AFRICA 53 structure throughout its history. However some evolutionary changes do occur, for instance : diminution of the basal pillars (in early gazelles these lie between the anterior and posterior lobes of the molar teeth on the inner side of the uppers and the outer side of the lowers), increasing hypsodonty, and an increasing depth of the mandibular ramus to house the longer teeth. The reason for the decline of the basal pillars (they may be retained in other groups such as the Reduncini and Bovini) is not easily understandable, but the other changes are obvious improvements of masticatory efficiency. But these modifications within Gazella are not so pronounced as those which occur in other gazelline genera and in the closely related Caprinae. The list of possible changes is : i. Little worn upper and lower molars come to possess transverse ridges across the anterior and posterior lobes. These ridges are seen on the dentine as well as on the enamel. 2. Accentuation of the styles on the outer walls of the upper molars. 3. A flattening of the outer walls of the upper molars between the styles. This may proceed to such an extent between the mesostyle and metastyle that the posterior outer surface becomes concave. OVIS M2. 0VI5 M2. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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