A NEW SPECIES OF DICERORHINUS (RHINOCEROTIDAE) FROM THE PLIO‐PLEISTOCENE OF MYANMAR

Abstract

A skull and mandible of the new species Dicerorhinus gwebinensis sp. nov. of Rhinocerotidae (Mammalia, Perissodactyla) is described. The material is collected from the upper part of the Irrawaddy sediments (PlioPleistocene) in central Myanmar. D. gwebinensis sp. nov. is morphologically more similar to the extant species D. sumatrensis (Sumatran rhinoceros) than to other species of the genus but differs from D. sumatrensis in having the comparatively shorter nasal, the more concave dorsal profile of the skull, the more elevated occiput and presence of molar crista in M3 ⁄ . This is the first discovery of Dicerorhinus in the upper Miocene to lower Pleistocene of the Indian subcontinent and Mainland Southeast Asia, and fills the chronological and geographical gap of this lineage in Asia. The Dicerorhinus clade probably migrated into Southeast Asia from East Asia by the Pliocene or early Pleistocene. This hypothesis is supported by the scarcity or absence of this clade in the Neogene mammalian fauna of the Indian Subcontinent.

A review of fossil rhinoceroses from the Neogene of Myanmar with description of new specimens from the Irrawaddy Sediments

“…Dicerorhinus gwebinensis Zin-Maung-Maung-Thein, Takai M., Tsubamoto T., Thaung-Htike, Egi N. and Maung-Maung, 2008 Comments: This species was discovered from the Plio-Pleistocene deposits of Irrawaddy sediments at the Gwebin area in central Myanmar (Fig. 1).…”

“…Fossil remains of rhinoceroses are common in the Neogene of central Myanmar and several species have been recognized (Pilgrim, 1910a;Colbert, 1938Colbert, , 1943Cotter, 1938;Chavasseau et al, 2006;Zin-Maung-Maung-Thein et al, 2006, 2008. However, most of the descriptions on these specimens have been provisional due to the fragmentary nature of materials.…”

A mongoose remain (Mammalia: Carnivora) from the Upper Irrawaddy sediments, Myanmar and its significance in evolutionary history of Asian herpestids

“…Nestoritherium), Proboscidea (Stegodon), Rodentia (Hystrix) (Colbert, 1943;Moe Nyunt, 1987;Tsubamoto et al, 2006;Thaung-Htike et al, 2006;Thaung-Htike, 2008;Zin-Maung-Maung-Thein et al, 2008. Among the known mammals from the Gwebin fauna, Propotamochoerus and Dorcabune are the forms from the middle Siwalik Group; thus, the age of Gwebin fauna has been considered as the late Pliocene rather than the Pleistocene (Zin-Maung-Maung-Thein et al, 2008).…”

“…Its thickness has been estimated to be 2000-3000 m (Bender, 1983;Wandrey, 2006). The age of sediments has been suggested to range from the late middle Miocene to Pleistocene based on faunal correlations (Colbert, 1938(Colbert, , 1943Bender, 1983;Chavasseau et al, 2006;Chit-Sein, 2006;Zin-Maung-Maung-Thein et al, 2008), and the sediments are traditionally subdivided into the 'Lower Irrawaddy' and 'Upper Irrawaddy' based on the lithological and paleontological criteria (Stamp, 1922;Colbert, 1935;Bender, 1983).…”

“…Pliocene to early/middle Pleistocene. The locality is included in the Gwebin fauna of the Irrawaddy sediments, and the age of fauna has been suggested as the late Pliocene (Zin-Maung- Maung-Thein et al, 2008).…”