Skull morphology in herbivore mammals: a comparative study case in macropodids (Metatheria, Diprotodontia, Macropodidae) and caviids (Eutheria, Rodentia, Hystricomorpha)

ÁLVAREZ, ALICIA; FLORES, DAVID A.

MASTOZOOLOGí­A NEOTROPICAL

UNIDAD DE ZOOLOGÍA Y ECOLOGÍA ANIMAL, INSTITUTO ARGENTINO DE INVESTIGACIÓN DE LAS ZONAS ARIDAS, CRICYT, CONICET

Lugar: Mendoza; Año: 2019 vol. 26 p. 241 - 254

0327-9383

Quantication of morphological diversity among herbivorous mammals and comparisonsbetween herbivorous marsupials and placentals are scarce. In this report we compared morphological variation of the skull and mandible in three representatives of caviid rodents and three species of macropodid marsupials, whose size is comparable, using three-dimensional geometric morphometrics. We applied two levels of comparison, one pointed to a placental-marsupial dichotomy and another pointed to the intra-variation in each group. We also performed an analysis of modularity based on a likelihood approach in order toevaluate dierent modularity models and analyzing the intra- and inter-module correlation (i.e., morphological integration). Beyond strong morphological dierences that split caviids and macropodids along the first axes of the morphospaces of the cranium and mandible, they shared similar allometric shape changes, including the enlargement of muscular attachment areas and lengthening of the diastema. In both clades, the largest value of inter-module correlation (as a measure of modular integration) was found for the oral-nasal andorbit modules. We reported relatively low values of within-module correlation for the oral-nasal and molar modules in macropodids while the opposite was recorded for caviids. Beyond the great dierences in cranial structure, one of the factors that inuence the patterns of morphological variation and dierential integration was the processing of plant matter which seems to induce strong structural changes in both clades, in which the eciency of the masticatory apparatus is resolved in a similar way.