DICKINSARTELLA FAUNA FROM THE SAIWAN FORMATION (OMAN): A BIVALVE FAUNA TESTIFYING TO THE LATE SAKMARIAN (EARLY PERMIAN) CLIMATIC AMELIORATION ALONG THE NORTH-EASTERN GONDWANAN FRINGE. RIVISTA ITALIANA DI PALEONTOLOGIA E STRATIGRAFIA , v. 111, n. 3, 30 Nov.2005.