A SOUTH CHINESE VERTEBRATE FAUNA FROM THE LOWER DEVONIAN OF THE LOWERBLACK RIVER (SONG DA), VIETNAM

A vertebrate fauna is described for the first time from the Lower Devo nian of the lower Black River (Song De) in Vietnam. It comprises essen tially placoderms, including a new antiarch, Songdalepis pustulata n.g ., n.sp., a primitive petalichthyid and possibly an actinolepid, but a lso a sarcopterygian which is thought to be closely related to Youngol epis, and some galeaspid fragments. At least three of these taxa have close relationships with endemic taxa from the Lower Devonian of the S outh China block (Yunnan, Guangxi and the north of Vietnam), thereby s uggesting that the Song Da area was the southern edge of the South Chi na block.