Chapter 9 Review of the investigation of primate fossils in Myanmar

Abstract

Since the discovery of fossil primates in the early twentieth century, the later Eocene Pondaung Formation in central Myanmar has attracted the attention from many palaeoprimatologists (Fig. 9.1). There were two large-bodied primates, Pondaungia cotteri and Amphipithecus mogaungensis (Fig. 9.2), known from two localities (Pangan and Mogaung) in the Pondaung area (Fig. 9.3), and many researchers have argued over the phylogenetic position of these two monkeys, that is, whether or not the Pondaung primates are anthropoids, higher primates which includes the clades of New and Old World monkeys, apes and humans. However, due to the scarcity of the fossil specimens, the controversy concerning the phylogenetic position of the Pondaung primates was not resolved until the 1970s. Some authorities believed they are primitive anthropoids, while others regarded them as adapiforms or non-primate, such as condylarthrans (Pilgrim 1927; Colbert 1937; von Koenigswald 1965; Szalay 1970; Simons 1971; Szalay & Delson 1979). Another problem confusing the taxonomy of the Pondaung primates is whether these two animals belong to the same taxonomic group or not. For example, Szalay & Delson (1979) discussed the Pondaung primates, allocating Amphipithecus to the adapiforms and Pondaungia to the early catarrhines. At that time, only a mandibular fragment preserving P3–M1 for Amphipithecus (Fig. 9.2d) had been found, while a mandibular but also a maxillary fragment preserving M1–2 had been discovered for Pondaungia (Fig. 9.2a). The upper molars of Pondaungia likely retained the ‘true hypocone’ which has been considered the definitive feature of anthropoid primates, but there was no information on the upper molars for Amphipithecus . Fig. 9.1. Geological map of central Myanmar showing primate fossil localities. Pondaung Formation: BHN, Bahin; MGN, Mogaung. Irrawaddy Sediments: YSK, Yinseik; GBN, Gwebin; CHZ, Chaingzauk (including Myokhinthar). (Modified after Geological Map of Myanmar, Myanmar …