Searching for Dental Signals of Exudativory in Galagos

Abstract

Consumption of exudates requires acquiring exudates. Exudate-feeding marmosets possess a distinct dental signal consisting of the "short-tusked" anterior dentition, which they use to gouge tree bark and elicit exudate flow. Observations of exudate-feeding galagos have indicated that these animals use the toothcomb in some fashion to acquire exudates, but behavioral observations of galago exudate acquisition are incomplete. The present study was designed to assess dental morphometrics of galagos in an effort to search for a more complete dental signal of exudate-feeding in this group. Cleaned and dried skulls from 137 galago specimens were selected representing seven species with varying proportions of exudates in their diets. Two-dimensional measurements were taken from the toothcomb, maxillary canine, mandibular and maxillary first premolars, and the last mandibular molar.

Exudativory in the Asian loris, Nycticebus: Evolutionary divergence in the toothcomb and M3

“…In addition to these linear measurements, a biomechanical shape variable for the ability of the toothcomb to resist bending in the parasagittal plane, as may be experienced during gouging activities, was also calculated (see Burrows and Nash, ; Vinyard, personal communication). To create this shape variable, the second moment of area for the toothcomb ( I xx ) was calculated.…”

“…As an alternative, we used the geometric mean of linear measures of size as a scaler for each dental variable (Mosiman, ; Jungers et al, ; Sokal and Rohlf, ; Coleman, ). In the present study, 16 craniodental variables were used to compute the geometric mean of each specimen (definitions shown in Table ): toothcomb mesiodistal length (TCL), toothcomb height (TCH), toothcomb labiolingual breadth (TCB), P 2 mesiodistal length (mandPL), P 2 vertical height (mandPH), P 2 buccolingual breadth (mandPB), M 3 buccolingual breadth (mandMB), M 3 mesiodistal length (mandML), maxillary canine mesiodistal length (maxCL), maxillary canine vertical height (maxCH), maxillary canine buccolingual breadth (maxCB), P 2 mesiodistal length (maxPL), P 2 vertical height (maxPH), P 2 buccolingual breadth (maxPB), maximum skull length, and maximum palatal length (after Burrows & Nash, ).…”

“… ( a ) Occlusal view of the mandibular dentition and, ( b ), lateral view of the right dentary in a representative specimen of Nycticebus coucang demonstrating select linear measurements used in the present study (after Burrows and Nash, ). In (a), the distance between the black dots at the toothcomb represents toothcomb mesiodistal length (TCL); the distance between the white dots at I 2 represents toothcomb height (TCH); the distance between the black dots at M 3 represents breadth (mandMB).…”

“…Eaglen () explained morphometric variation among taxa in the toothcomb as instead being more reflective of selection for a grooming function, a notion that has been suggested in other studies (e.g., Eaglen, ; Rose et al, ; Rosenberger and Strasser, ; Asher, ). Recently, Burrows and Nash () demonstrated few morphometric differences in the toothcomb of highly exudativorous galagos ( Euoticus elegantulus and Otolemur crassicaudatus ) relative to galagos that do not intensively consume exudates. Most morphometric dental differences were evident in the relatively larger upper and lower premolars and the upper canine in exudate‐specialists relative to the non‐specialists.…”

Social variables exert selective pressures in the evolution and form of primate mimetic musculature

“…For example, dentition within primates that are primarily seed-eaters, gum and sap-eaters, and fruit feeders shows unique morphological features linked to acquiring and processing these particular foods (e.g. Hylander, 1975;Lambert et al 2004;Burrows & Nash, 2010;Burrows et al 2015). Mandibular morphology has similarly been linked to dietary niche across a range of primate taxa (e.g.…”