Similar Mechanical Forces in Hemimandible Goat Breeds

Abstract

The mammalian mandible is generally seen as a functional unit as a lever during biting. Allometry can be an important factor that contributes to adaptative traits and its variation. The purpose of this study was to determine if there is an allometric relationship in goat hemimandible. For this purpose, seven hemimandibles belonging to wild Capra pyrenaica and 43 more belonging to different domestic goat breeds were studied. Digital photographs were used to obtain two distances: from the temporo-mandibular to the middle of the cheek teeth row, and from the temporo-mandibular articulation to the bottom of the angular process. Our analyses determined that goat hemimandibles exhibit positive allometry (r2=0.658), which hints at fundamental constraints in goats due to their size differences. Nevertheless, in view of methodological constraints (exclusively morphometrical data, small sample size, lateral landmarks¿) we caution that this similar functional pattern of mandible can not exclude adaptative patterns.

Authors are indebted to the staff at the Natural History Museum of Barcelona (Catalonia), especially its Curator of Mammals, Dr Javier Quesada, for loaning part of the specimens and their associated information, and JosuéSabaté, for his disposal of Rasquera skulls