Oral Presentation- Symposium 12th International Mammalogical Congress

Evolution of cranial development in marsupials (#475)

Norberto P Giannini 1 , David A Flores , Fernando Abdala
  1. Unidad Ejecutora Lillo, San Miguel De Tucumán, Tucumán, Argentina

Cranial ontogeny in mammals has been quantitatively studied in a number of lineages. In this report, we integrate the information of allometric growth from 15 skull variables that define shape and approximately represent (sensory, mechanical) functions of the skull. We estimated multivariate coefficients of allometry, and their resampled confidence intervals, of those 15 variables for 24 marsupial species from 10 living families, using 4 placentals as comparative outgroups. Confidence intervals were optimised in a well resolved phylogeny. Optimisations show changes in most internal nodes, although we did not detect synapomorphies either in marsupial or placental basal nodes, suggesting the conservation of an ancient therian growth pattern of Mesozoic age. Ameridelphia is defined by a growth rate increase in orbits and the height of the muzzle, and decrease in length of the coronoid process. Australidelphia is defined only by a decrease of the confidence interval of the height of the coronoid process. We detected synapomorphies in almost all subclades (except Dasyuromorpha and Phalangeridae). The variables with phylogenetic signal were those related with growth of the mandible, and marginally, breadth of the braincase and length of the upper toothrow. These results describe, from a developmental perspective, the way skull components evolved in marsupials, and show a remarkable correspondence of cranial ontogeny and marsupial lineage evolution.