INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
HETEROCHRONY AND POSTNATAL GROWTH IN MAMMALS ─ AN EXAMINATION OF GROWTH PLATES IN LIMBS
GEIGER, M.; FORASIEPI, A.M.; KOYABU, D.; SANCHEZ-VILLAGRA M.
Congreso; 10th International Congress of Vertebrate Morphology; 2013
Extant mammals display a broad spectrum of limb specializations coupled with different locomotor strategies and habitat occupation. This anatomical diversity reflects different patterns of development and growth, including the timing of epiphyseal growth plate closure. We investigated the sequence of union in 15 growth plates in the limbs of more than 400 specimens, representing 34 genera and 59 species: 33 placentals, 25 marsupials, and one monotreme. The relative age of the specimens was estimated by dental eruption and wear. We found a common trend of growth plate closure sequence, but one that is universal neither among species nor in higher order taxa. For example, the girdle elements (acetabulum and supraglenoid tubercle) ossify first in marsupials whereas the distal humerus is fused before the girdle in some placentals. Moreover, unlike placentals, marsupials maintain many epiphyses separated during the entire life. Lapsed epiphyseal growth plate closure is particularly known from reptiles. However, as complete union of all epiphyseal growth plates is recorded in monotremes, the marsupial condition might represent the derived state. Locomotor habitat has no detectable correlation on the growth plate closure sequence. The variation recorded in the sequence of epiphyseal growth plate closure in different breeds of domesticated forms provides clues on the heterochronic patterns that characterize the generation of morphological diversity.