Morphometrics of the anterior dentition in strepsirhine primates

Abstract

Size variations in the anterior dentition were analyzed for 26 species of strepsirhine primates. The upper and lower incisor rows of strepsirhines, like those of anthropoid primates, scale isometrically with body size. Within the order Primates, strepsirhines exhibit the smallest incisors relative to body size, followed in increasing size by tarsiers, platyrrhines, and catarrhines. If the lateral teeth of the indriid toothcomb are interpreted as incisors and not canines, correlations between mandibular tooth size variables and body weight are maximized. The upper incisors of strepsirhines are extremely small and frequently widely separated, most likely to minimize occlusion with the toothcomb. Species deviations for assorted size variables of the anterior dentition generally fail to reflect functional variations in the use of the anterior teeth; some of the variables, however, do reflect taxonomic differences within the Strepsirhini. Although toothcomb size variations among extant strepsirhines are more readily interpreted in terms of gum feeding and bark scraping than they are in terms of grooming, anterior dental morphology as a whole is more easily explained by a grooming hypothesis when existing models of toothcomb origins are considered.

Searching for Dental Signals of Exudativory in Galagos

“…after Masters and Brothers 2002). However, Eaglen (1986) found no trends in morphological adaptations in the toothcombs of any of these taxa that reflect exudate acquisition.…”

“…senegalensis feeding behavior have provided evidence that they use their toothcombs in some fashion to access exudates (Bearder and Martin 1980). Charles-Dominique (1977) and Eaglen (1986) observed that E. elegantulus and O. crassicaudatus have relatively narrow and high toothcombs compared with galagos that do not intensively exploit exudates. If exudativorous galagos are using the toothcomb to acquire difficult-to-reach exudates by using a high, narrow toothcomb, we predict that this morphological dental signal would be seen in a large sample of galago exudate feeders.…”

“…The toothcomb has frequently been cited as a dental adaptation for exudate acquisition in the strepsirrhines (Martin 1972(Martin , 1979Gingerich 1975;Charles-Dominique 1977;Bearder and Martin 1980). Eaglen (1986) noted, though, that there were few morphometric adaptations in the toothcomb that distinguished exudativorous strepsirrhines from those that occupied other dietary niches. However, he did find that the most highly exudativorous strepsirrhines, Euoticus, Phaner, and Otolemur crassicaudatus (termed Galago crassicaudatus therein), tended to have high [cementoenamel junction to tip (CEJ-tip)] and mesiodistally narrow toothcombs relative to other strepsirrhines.…”

“…8). Charles-Dominique (1977) and Eaglen (1986) noted that Euoticus and Phaner had a uniquely mesiodistally narrow and high (CEJ-tip) toothcomb among strepsirrhines and suggested that these dimensional characteristics may be useful in accessing difficult-to-reach exudates relative to a wide and low toothcomb, forming an efficient "gouge" or "scoop" (Martin 1990;Kinzey 1992). In general, though, it is unclear what posterior dental morphologies characterize exudativorous galagos (or other strepsirrhines) and which teeth they may use to acquire exudates besides the toothcomb.…”

The Evolution of Exudativory in Primates

“…It is also generally accepted that the specialized gummivores Euoticus and Phaner have distinctive tooth-scrapers. However, the association between tooth-scraper dimensions and exudativory is not particularly strong when seen across strepsirrhines generally (Eaglen 1986). Moreover, comparison of specialized exudativores, moderate exudativores and nonexudativores among galagids provides only limited support for a connection between tooth-scraper dimensions and exudativory (Burrows and Nash, Chap.…”