Shrew Opossums: Paucituberculata

DYNASTY IN EXILE

Like the few poor refugees of a downfallen, once mighty civilization, the five living shrew opossum species, lurking in the undergrowth of temperate forests in South America, are but a pale afterglow of their former splendor. From seventeen to twenty-four million years ago, the order Paucituberculata included four other families besides Caenolestidae, while the caenolestids were the most abundant marsupials in terms of species during that era. The extinct Paucituberculata species had teeth specialized in unique ways, and lived in both temperate and tropical biomes throughout most of the South American continent.

The extinct families of Paucituberculata are Paleothentidae, Abderitidae, Polydolopidae, and Argyrolagidae. Species of Paleothentinae had developed an enlarged forward lower molar with a shearing crest. Abderitinae species took that molar further and equipped it with a forward-facing, sharp, high, serrated blade. The species of Polydolopidae carried a number of enlarged, forward-directed lower incisors and a pair of large shearing teeth of uncertain origin. The Polydolopidae were small marsupials, the largest no bigger than a rabbit, that behaved and were equipped like rodents. The rodent-like Argyrolagidae resembled small kangaroos, with two-toed hind feet and a long, well-muscled tail. They moved about by hopping and leaping, much like kangaroos. Family Paleothentidae evolved an impressive nine genera and nineteen species.