• distal fibula
• functional morphology
• primate
• trabecular bone

Within my thesis work, for the first time the trabecular bone is analyzed in the distal epiphysis of the fibula, in an extant primate sample. The goal is to determine a relationship between locomotion behaviour (arboreal/terrestrial) and fibular trabecular morphology, by means of an evaluation of the adaptive response of trabecular bone to mechanical stimuli and the different loads on the ankle joint during arboreal/terrestrial activities. I had the availability of 67 individuals’ micro-CT scans (resolution 100 micrometers), thanks to the University of Witwatersrand, South Africa. They belong to Chlorocebus aethiops (n=24), a mixed arboreal-terrestrial species, Papio ursinus (n=24), a highly terrestrial species, and Homo sapiens (n=18), the most terrestrial primate. Because of the resolution, in this first sample I could compute only the degree of anisotropy (DA) in a reliable way, and my expectation is a statistically higher DA in terrestrial species, since their ankle experiences a highly stereotyped loading pattern. Moreover, I exploited two additional samples. The first consists of 17 left fibulae, provided me by La Specola Museum, Florence: Chlorocebus sp. (n=1), Chlorocebus aethiops (n=1), Chlorocebus pygerythrus (n=1), Colobus guereza (n=4), Papio sp. (n=1), Papio cynocephalus (n=1), Papio hamadryas (n=1), Propithecus diadema (n=1), Ateles paniscus (n=2), Alouatta seniculus (n=1), Cercopithecus albogularis (n=2), Macaca nemestrina (n=1). This sample allowed me to study a wider taxonomical/locomotor range but with a lower sample size. The second sample consists of 3 human fibular specimens (necropolis of Olmo di Nogara, Verona). On these two additional samples, micro-CT scans were performed at National Research Council in Pisa, obtaining images with a resolution of 26-35 micrometers. It allowed me to compute 6 parameters (DA, BV/TV, Tb.Sp., Tb.Th., Conn.D., SMI), differently from the South African sample. Trabecular variables were extracted from two cubic VOI’s (one for each of the two joint surfaces between fibula and talus). They were scaled according to the joint size (actually a proxy of body size), using previously published data (Marchi 2015). Moreover, they were positioned just below the cortical-trabecular interface and in the central part of each joint surface. I performed the image processing step in Avizo 6.3. whereas trabecular architecture was quantified through ImageJ. Because of the heterogeneity in resolution, from a statistical point of view the interspecific analysis was divided in two parts. The first concerns a univariate quantitative approach (ANOVA), exploiting DA data in the sample from South Africa. The second part is a multivariate qualitative analysis (PCA without post-PCA statistical tests, because of the low sample size); thus, an entire suite of trabecular variables (6 per specimen) are analyzed in the two additional samples, in order to find a differentiation, according to locomotion behaviors. Highly terrestrial and highly arboreal species are expected to occupy two extreme positions in the scatterplot, while mixed arboreal/terrestrial species are expected to be in between the two extremes. Since the present study is preliminary, a qualitative approach can however provide some insights for future studies.