AVOIDING COMPETITION: THE ECOLOGICAL HISTORY OF LATE CENOZOIC METATHERIAN CARNIVORES IN SOUTH AMERICA

ZIMICZ ANA N.

JOURNAL OF MAMMALIAN EVOLUTION

SPRINGER

Lugar: Berlin; Año: 2014

1064-7554

The ecological interaction between small and medium sized South American metatherian carnivores, from the Miocene to Recent, has been analyzed with the objective to understand the ecological interactions between the Hathliacynidae (Sparassodonta) and some Didelphoidea (Didelphimorphia). The species richness through time for these two groups, along with the body mass, diet and several morphofunctional variables has been analyzed here. The results show a double-wedge geometry of the diversity curve. The climax of the Hathliacynidae took place during the Santacrucian mammal-age with a subsequent decline, in the species richness of this family, followed by the extinction of the family at the Barrancalobian subage. Carnivorous Didelphoidea show a first maximum species richness during the Chapadmalalan followed by a decline and a new rise during Recent times. The coexistence of these mentioned groups took place from the Chasicoan to the Chapadmalalan mammal-ages covering a time span of around six million years. The multivariate and univariate analyses of morphofunctional variables suggest a restriction of the Hathliacynidae to hypercarnivory while the Didelphoidea occupied the niche of meso- and hypocarnivory. The body mass analyses show some overlap in small sizes but it is not correlated with any superposition in the morphospace of functional variables. In summary, any passive replacement or active displacement between the Hatlhyaciniidae and carnivorous Didelphoidea are supported by the fossil record. In turn, a partition of the metatherian carnivorous guild seems to have occurred through to the Neogene. The extinction of the Hathliacynidae seems to be a result of environmental change.