Early Carboniferous age for Arynshand Formation,Mongolian South Gobi,based on conodonts

Conodonts from the lowermost part of the Arynshand Formation at the Bayan-Khoshuu Ruins section in the Mushgai area, south Gobi, including Siphonodella cooperi, S. cf. crenulata and S. cf. isosticha, clearly indicate that the Arynshand Formation is Early Carboniferous rather than Devonian-Carboniferous. The formation rests unconformably on the volcanogenic Minjin Member of the Botuulkhudag Formation from which we have not recovered conodonts. The Arynshand Formation contains some presumably reworked Devonian conodonts which cannot be used to provide a reliable age.