Archidiskodon planifrons (Falconer et Cautley) from the Tatrot zone of the Upper Siwaliks

Although the discovery of the elephantine mentioned in the title of the present contribution dates from the early days of collecting in the Siwalik Hills (Falconer and Cautley, 1845, pl. 2 figs. 5a, 5b, as Elephas planifrons the stratigraphical position of this species within the tremendously thick Siwalik series of continental deposits was first settled only in 1913, when Pilgrim wrote: “There is absolutely no trace of Elephas either in the Middle Siwalik or in the Tatrot zone of the Upper Siwalik. It first appears as the species Elephas planifrons some 2,000 feet above the base of the Tatrot zone” (Pilgrim, 1913, p. 294), that is, within the Pinjor zone. Hence, Pilgrim (1. c., pl. 26) assigns Archidiskodon planifrons (Falconer et Cautley) to the Pinjor zone of the Upper Siwaliks. Meanwhile, molars indistinguishable from those of the Siwalik A. planifrons had been discovered in Bessarabia, Southern Russia (Pavlow, 1910, p. 27, pl. I fig. 23) and in Lower Austria (Schlesinger, 1912, p. 89), in strata which were then considered to be approximately of Upper and of Middle Pliocene age respectively. In accordance with this, Pilgrim (l.c., p. 323) regards the Pinjor zone as Middle to Upper Pliocene, and the underlying Tatrot zone, the basal beds of the Upper Siwaliks, as Lower Pliocene. However, he states further that, if some subsequent discovery should bring to light a specimen of A. planifrons in the basal beds of the Upper Siwaliks, it would then be impossible to regard the Tatrot zone as much older than the occurrences of this species in Europe (l.c., p. 295). Unfortunately, the beautiful specimens of Archidiskodon planifrons collected in 1922 by Barnum Brown in the Upper Siwaliks around Kalka were loosely embedded in sand, occurring in gullies or depressions, and consequently are of uncertain stratigraphie position; yet Osborn (1942, pp. 950—959) regards these molars as having been derived from the Pinjor zone.