Morphometric Studies of the Axial Skeleton of the African Giant Rat (Cricetomys gambianus, Waterhouse) Part (1): Skull Typology

Abstract

The purpose of this study was to investigate some aspects of the skull typology of the African giant rat. In this study, 16 adult African giant rats (Cricetomys gambianus, Waterhouse) of both sexes were used to investigate the bones of the cranial skeleton. The dimensions of excised skulls were measured directly using pre-established anatomical points. Morphometric analysis of the skulls showed important measurements and features; the intercondylar width was 1.45 ± 0.02cm. The mean nasal length in females at 2.93 ± 0.05 cm was longer than the 2.76 ± 0.06 cm of male. The infraorbital foramen was large in the African giant rat with the greatest length being 0.75 ± 0.02 cm while the greatest breadth was 0.52 ± 0.02 cm. Maximum mandib-ular height and length were 2.13 ± 0.02 cm and 3.62 ± 0.04 cm respectively. Four parameters were statistically significant at P< 0.05 between both sexes and include the intercondylar width, temporal bone height, external auditory pore height and the sub arcuate fossa height; these could thus serve as basis for sexual dimorphism. Major morpho-logic findings include the presence of a ventral mandibular foramen, a complete jugal arch and presence of jugal foramen. This work has provided morphometric information that will aid in sexual dimorphism and taxonomy of the African giant rat.