Meeting Abstract

P1-71   -   Influence of Phylogeny and Locomotor Mode on Caniform Astragali Munteanu, VD*; Brennan, PLR; Merriman, M; Hedrick, BP; Clemson University, Clemson, SC; Mount Holyoke College, South Hadley, MA; Xavier University of Louisiana, New Orleans, LA; Louisiana State University Health Sciences Center, New Orleans, LA vmuntea@g.clemson.edu

Mammals of the suborder Caniformia have diversified into a multitude of locomotor modes, including high within-clade locomotor diversity. Within mammals, postcranial morphological indicators of locomotor mode often focus on the ankle joint, composed of the astragalus and calcaneus bones. Previous morphometric work on the caniform calcaneus has uncovered morphological distinction between locomotor modes and even some families. The astragalus, however, is relatively understudied. Astragali from 57 species across were micro-CT scanned and were then subjected to three-dimensional geometric morphometrics. These taxa ranged across the caniform tree and contained taxa with the full range of caniform locomotor modes (cursorial, scansorial, semi-aquatic, semi-fossorial, terrestrial). Shapes were digitized in the Auto3DGM package in 3DSlicer using a double pass alignment with 100 and 1000 landmarks respectively. Blomberg’s K statistic generalized for multidimensional data (Kmult) was highly significant. Principal component analysis strongly indicated tight phylogenetic grouping, with ursids and canids in particular grouping tightly in morphospace. Conversely, locomotor groups were relatively scattered across morphospace and were clustered by family. Procrustes ANOVAs were used to assess the relationship between astragalus shape and phylogenetic family, and indicate that 66% of the shape variation within the suborder is associated with family. Of the remaining 34%, only 15% is associated with locomotor mode. When phylogeny is excluded from ANOVA, locomotor mode explains a more substantial amount of variance (~60%) indicating a strong correlation between family and locomotor mode. These results indicate that despite some influence of specific locomotor mode on astragalar morphology, phylogeny consistently has a strong influence on astragalar shape, differing from the findings in the previous calcaneus work.