NOTHOFAGUS-BEARDMORENSIS (NOTHOFAGACEAE), A NEW SPECIES BASED ON LEAVES FROM THE PLIOCENE SIRIUS GROUP, TRANSANTARCTIC MOUNTAINS, ANTARCTICA

Leaves from the Late Pliocene Sirius Group at Oliver Bluffs in the Dom inion Range, Transantarctic Mountains, are assigned to the new species Nothofagus beardmorensis Hill, Harwood et Webb, sp. nov. The plant wh ich produced the leaves was winter deciduous, and it is probable that the wood and pollen of Nothofagus that co-occur in the sediments are c onspecific with N. beardmorensis. The presence of this species in Anta rctica in the Pliocene suggests a much different climate than at prese nt, since no extant Nothofagus species can survive temperatures below about -22 degrees C in winter, and temperatures must have been substan tially above 0 degrees C for a relatively long period during the growi ng season for the growth and reproductive effort observed. A prelimina ry estimate of a 13-15 degrees C temperature difference between fossil deposition and the present day is inferred.