Locomotor adaptations in scapular shape in carnivorans

TY - GEN

T1 - Locomotor adaptations in scapular shape in carnivorans

AU - Gálvez-López, Eloy

PY - 2013

Y1 - 2013

N2 - The relationship between scapular shape and locomotor pattern in Carnivora was studied on 213 scapulas from 101 species representing the whole locomotor range of extant carnivorans. The 34 3D-landmarks digitized were analysed using geometric morphometrics. Locomotor-related shape differences were assessed using canonical variate analysis (CVA) and discriminant function analysis (DFA). The first two canonical variates of the CVA defined a shape space that clearly separated all locomotor categories (all paired comparisons were significant), accounting for 82.4% of shape variation. However, high DFA misclassification rates were obtained when comparing semiarboreal and semifossorial carnivorans, and both with scansorial and terrestrial carnivorans. Due to their extreme locomotor adaptation, aquatic carnivorans had the most characteristic scapular shape, presenting the relatively shortest and widest scapulas with the relatively least protruding spines in the sample. Aquatic carnivorans also presented an expansion of the cranial portion of the vertebral border, and lacked well-developed acromial processes. The secondary adaptation to swimming of semiaquatic carnivorans was evidenced by the mix of features shared with (e.g. short scapular blade, wide and flat supraspinous fossa) and opposed to (e.g. high spine, the smallest infraspinous fossa, well-developed acromial processes) aquatic carnivorans. Several shape changes were associated with increased arboreality (terrestrial – scansorial – semiarboreal – arboreal), namely a shortening and widening of the scapular blade (especially at the infraspinous fossa), a cranial displacement of the proximal portion of the spine (greatly increasing the proximodistal curvature of the spine), a medial shift of the glenoid cavity (which also becomes cranially adducted), and acromion and metacromion becoming coplanar. Finally, although scapular shape in carnivorans is significantly affected by size and phylogenetic relatedness, corrections for both factors had no significant effect on either CVA or DFA results. Thus, locomotor adaptations in the scapular shape of extant carnivorans seem independent of size or shared ancestry.

AB - The relationship between scapular shape and locomotor pattern in Carnivora was studied on 213 scapulas from 101 species representing the whole locomotor range of extant carnivorans. The 34 3D-landmarks digitized were analysed using geometric morphometrics. Locomotor-related shape differences were assessed using canonical variate analysis (CVA) and discriminant function analysis (DFA). The first two canonical variates of the CVA defined a shape space that clearly separated all locomotor categories (all paired comparisons were significant), accounting for 82.4% of shape variation. However, high DFA misclassification rates were obtained when comparing semiarboreal and semifossorial carnivorans, and both with scansorial and terrestrial carnivorans. Due to their extreme locomotor adaptation, aquatic carnivorans had the most characteristic scapular shape, presenting the relatively shortest and widest scapulas with the relatively least protruding spines in the sample. Aquatic carnivorans also presented an expansion of the cranial portion of the vertebral border, and lacked well-developed acromial processes. The secondary adaptation to swimming of semiaquatic carnivorans was evidenced by the mix of features shared with (e.g. short scapular blade, wide and flat supraspinous fossa) and opposed to (e.g. high spine, the smallest infraspinous fossa, well-developed acromial processes) aquatic carnivorans. Several shape changes were associated with increased arboreality (terrestrial – scansorial – semiarboreal – arboreal), namely a shortening and widening of the scapular blade (especially at the infraspinous fossa), a cranial displacement of the proximal portion of the spine (greatly increasing the proximodistal curvature of the spine), a medial shift of the glenoid cavity (which also becomes cranially adducted), and acromion and metacromion becoming coplanar. Finally, although scapular shape in carnivorans is significantly affected by size and phylogenetic relatedness, corrections for both factors had no significant effect on either CVA or DFA results. Thus, locomotor adaptations in the scapular shape of extant carnivorans seem independent of size or shared ancestry.

M3 - Conference contribution

VL - 296

SP - 194

EP - 195

BT - Anatomical Record

T2 - 10th International Congress of Vertebrate Morphology

Y2 - 8 July 2013 through 12 July 2013

ER -