Relaciones de similitud, paleoecología y extinción de los Abderitidae (Marsupialia, Paucituberculata)

Abstract

Similarity relationships of the three genera and seven species of the extinct South American family Abderitidae, a marsupial group with a plagiaulacoid type of molariforms, are presented using multivariated analysis techniques. Also, the paleoecology and the inferred causes of extinction of these marsupials are discussed. In the multivariated analysis, the relationships between all the species of the family were studied. Sixteen characters were employed, eleven qualitatives and five quantitatives. The results of the multivariate analysis: 1) support the previous supraespecific classification; 2) indicate that the genus Abderites and Pitheculithes are related across the species A. meridionalis and P. chenche; 3) indicate that the genus Parabderites and the group Pitheculithes+Abderites are related across the species Parabderites minusculus and Pitheculithes chenche; and 4) show that the specimens determined as Parabderites sp. are more closely related with P. bicrispatus than with P. minusculus. Finally, on the basis of the available paleoecological evidences (specific richness and relative abundance, diet, habitat, and body size) it is possible to infer that: 5) the three groups of South American marsupials with a plagiaulacoid type of molariforms (i.e., Polydolopidae, Palaeothentidae, and Abderitidae) had similar ecological requirements; 6) the Polydolopidae were opportunistically replaced by Palaeothentidae and Abderitidae; and 7) the post-Friasean extinction of Palaeothentidae and Abderitidae was physically rather than biologically driven, marking a great difference with the apparent causes of decline and extinction of the similarly adapted multituberculates and plesiadapiforms in North America.