DOS NUEVOS MARSUPIALES "PSEUDODIPROTODONTES" DEL EOCENO DE PATAGONIA, ARGENTINA

Abstract

Quirogalestes alniagaucha n. gen. et sp. is an early Eocene Pichipilinae (Paucituberculata, Caenolestidae) distinguished from Pichipilus and Phonocdromus by the larger size of its p3, and by having a lower molar pattern that is primitive with respect to those of Pichipilus and Phonocdromus. The protoconid is less reduced, the anterobasal cingulum is moderately developed, and the paraconid and metaconid are only slightly separated. The holotype, and only known specimen, was recovered from middle levels of Casamayor Fm. (Casamayoran Age; early Eocene) at Cerrito Fructuoso, in Valle Hermoso (Chubut Province, Argentina). It represents the oldest and more generalized pichipiline known to date. The middle Eocene Hondonadia feruglioi n. gen. et sp. (?Polydolopimorphia) resernbles several polydolopimorphians in the size of its upper canine, the length and width of the incisive vacuities, an upper molar pattern characterized by a well-developed "hypocone" (displaced metaconule), and a (moderate) twinning of the paracone and metacone with stylar cusps B and D, respectively. The holotype, and only known specimen, comes from middle Eocene (Mustersan Age) levels at Gran Hondonada (= "Pozón Grande"; Sarmiento Group), near Paso de Indios (Tehuelches Department, Chubut Province, Argentina). It may represent the persistence (into well-advanced Paleogene times) of a relatively generalized polydolopimorphian quadritubercular molar pattern, which was already established in southern South America by the middle Paleocene. KEY WORDS. Marsupialia. Paucituberculata. Polydolopimorphia. Systematics. Eocene. Patagonia.