THE AGE OF THE NEOSELACHIAN FAUNA OF THE THANIYAT PHPSPHORITE MEMBER, NORTHWESTERN SAUDI ARABIA

The Thaniyat Phpsphorite Member is a 30-40 meter thick sedimentary unit that is exposed in northwestern Saudi Arabia, and is a part of the Late Cretaceous-Early Tertiary phosphatic belt that extending from Morocco to India. The age of this unit has been debated to be Maastrichtian and/or Paleogene in informal publications or personal communications that needs to be Reviews and rectified. Recent collaboration between SGS (Saudi Geological Survey), KSU (King Saud University), and UM (University of Michigan) resulted in sampling several beds of phosphates and phosphatic sediments from the Thaniyat Phpsphorite Member exposed along the southern edge of the Jibal al Tubayq and in Wadi Al Faiha in the northwestern part of Saudi Arabia. Fossil neoselachian (sharks and rays), mainly teeth, were the main component in our analysis. These were collected from two distinctive levels of this member. The lower level the contact between the sandstone facies of what is known as the Zallum Formation of the Aruma Group and the Thaniyat Phpsphorite Member of the Jalamid Formation (Turayf group). While the upper level to produce these fossils is above the fissile shale topping the Phosphatic sandstone including the same level of the 1970 USGS phosphate adit. Preliminary results from washing and picking produced at least a dozen of sharks and rays teeth found in both levels. The fauna include the following species: Ginglymostoma sp., Serratolamna cf. khderii, Serratolamna serrata, Cretolamna appendiculata, Squalicorax kaupi, Squalicorax bassanii, Squalicorax pristodontus, Parapaleobates atlanticus, Schizorhiza stromeri, Dalpiazia stromeri, Rhombodus binkhorsti, Rhombodus sp., and Dasyatis sp. The Neoselachian fauna obtained from both levels seem to be similar in diversity, taphonomy, and preservation. The Thaniyat Phpsphorite Member is early Maastrichtian age. This is due to the great similarities of the fauna found here and the neoselachian faunas found in the Al Hasa Phosphorite Formation on the Jordanian side in the localities of Naqb Etaiiq and Esh-Shidiya Phosphate Mine. Also the fauna of the Thaniyat Phpsphorite Member is part of a more diverse fauna from the Maastrichtian phosphate of Egypt.