Middle Miocene Uruguaytheriinae (Mammalia, Astrapotheria) from Peruvian Amazonia and a review of the astrapotheriid fossil record in northern South America

摘要

Five mandibular and dental specimens referred to the extinct South American ungulate clade Astrapotheria are described. They originate from late middle Miocene deposits of the Ipururo Formation in the Río Inuya-Río Mapuya area, Peruvian Amazonia. The first Peruvian astrapothere remains unearthed in a controlled stratigraphical context reveal the co-occurrence of the uruguaytheriine astrapotheriids Xenastrapotherium sp. and Granastrapotherium cf. snorki. Bispecific uruguaytheriine assemblages were so far restricted to the early Miocene of Venezuela and the late middle Miocene of Colombia. The Fitzcarrald local fauna, including the uruguay theriines described here, recalls unequivocally the Xenastrapotherium kraglievichi Cabrera, 1929-Granastrapotherium snorki assemblage, which characterizes the 13.6-12.76 Ma interval in the Honda Group of La Venta area, Colombia. The spatio-temporal distribution of low-latitude astrapotheriids (< 30°S) is then reviewed, illustrated, and further detailed in both stratigraphical and taxonomic points of view. The group appears in the fossil record during the Oligocene or the earliest Miocene (Uruguaytherium Kraglievich, 1928 and Xenastrapotherium Kraglievich, 1928 in Uruguay and Venezuela, respectively). Uruguaytheriinae are conspicuous elements of middle Miocene mammal assemblages of northern South America (Colombia, Brazil, Bolivia, and now Peru). Astrapotheria probably become extinct during the late Miocene (Huayquerian South American Land Mammal Age), but the youngest specimens are of uncertain taxonomic affinities and/or might be reworked (Astrapotheriidae indet. in Urumaco Formation of Venezuela; ?Astrapotheria in Rio Acre local fauna of Brazil).