83 



Allc^metrics 



Intergeneric allometrics 



Although allometric approaches usually are chosen in different size relations of the 

 systematic sample taxa (in individuals of equal size, proportion differences would stand 

 out aheady by smiple comparison of the values), it may nevertheless be useful to analyse 

 allometries even in individuals of almost same size, as allometrics sometimes do differ in 

 individual features even in species of equal dimensions. 



Referring to nectar intake, some specialized flower bats show an extremely prolonged 

 rostrum. Relative length to total skull lengtli varies considerably between individual 

 species. So, there are differences in relative length of the visceral skull both between the 

 species of a genus and between inidivual genera. Furthermore, the species show 

 considerable differences in body size (factor up to 1.8). Thus, it was to examme whether 

 different proportions can be explained by aUometry - and whether the rostra of different 

 size foUow the same principles of construction. 



From the total of 17 skull measures mvolved in univariate analysis, five allometric 

 parameters which are especially affected by rostrum prolongation were related to SIZE: 



1. Width over canini (CC) (figs. 61-62): This measure gives information on terminal 

 rostnmi width and affects the geometry of the visceral skull with respect to its relative 

 size. 



2. Upper tooth row (OZR) (figs. 63-65): Distinct assigmnent of the canine, premolar and 

 molar alveoli to the maxillaria allows to determine relative length of these maxillar bones. 

 It remains, however, important to consider tlie dental formula and the number of 

 postcanine teeth, respectively, in the upper jaw. 



3. Length of the palate (GL) (figs. 66-70): Apart from the maxillaria, primarily the 

 palatinae become stretched in the course of rostrmn prolongation. Thus, this measure 

 compared to the braincase (SIZE) also gives information on relative prolongation of the 

 visceral skull. The conspicous contours of the proxunal palate edge variy in individual 

 species between sharply V-shaped over smootlily U-shaped up to a weakly rounded, 

 almost straight form. Tlius, tliis measure is considerably determined by the construction of 

 the bony palate. 



4. Length of mandible (UKL) (fig. 71): Tliis measure reflects a very useful correlate of the 

 respective rostrum length. Compared to OZR and GL it has the advantage that a) the 

 measure also comprises the rostral part anterior of the canines, b) none of the 

 constructions not origmally associated with the visceral skull will affect the measure, and 

 c) the measures are easily accessible. 



5. Coronoid height (CH) (fig. 72): Representmg an expression for the functional 

 significance of the M. temporalis for the mter locking jaws, the relation of coronoid height 

 to braincase (SIZE) gives information on relative importance of the chewmg process, tlius 

 considering an important aspect of functional morphology in the analysis of rostnmi 

 prolongation. 



The data given earlier (p.66) lead to the foUowmg statements: 



Width over canini (C-C): In tlie genera Carollia and Phyllostomiis summarized in the 

 outgroup, the canine distances are comparatively wider than in tlie Glossophaginae and 

 Lonchophyllinae (fig. 50, tab.5). 



