Cretaceous Research (2000) 21, 553–562 doi:10.1006/cres.2000.0217, available online at http://www.idealibrary.com on Late Campanian ammonites from the Saiwan area (Huqf Desert, Sultanate of Oman) *W. James Kennedy, †John W. M. Jagt, ‡Samir S. Hanna and †Anne S. Schulp *Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK; e-mail: Jim.Kennedy@earth.ox.ac.uk †Natuurhistorisch Museum Maastricht, PO Box 882, NL-6200 AW Maastricht, the Netherlands; e-mail@nhmmaastricht.nl ‡Sultan Qaboos University, College of Science, PO Box 36, Al-Khod 123, Sultanate of Oman; e-mail: hanna@squ.edu.om Revised manuscript accepted 31 March 2000 Recently collected ammonite faunules from the Samhan Formation (Aruma Group) exposed south of Saiwan (Huqf Desert, Sultanate of Oman) comprise three species, Kitchinites angolaensis Howarth, 1965, Pachydiscus (P.) arabicus Kennedy & Jagt sp. nov., and Manambolites dandensis Howarth, 1965. These taxa allow the middle and upper members of this formation to be dated as Late Campanian, based on the stratigraphic ranges of the ammonite taxa elsewhere (Israel, Angola). A previous age assignment (Early Campanian) to this formation was based primarily on foraminiferal and calcareous nannoplankton dating of the overlying Fiqa Formation.  2000 Academic Press K W: ammonites; Campanian; Late Cretaceous; Sultanate of Oman; new taxon. 1. Introduction In February–March 1998, staff members of the Vrije Universiteit Amsterdam, the Natuurhistorisch Museum Maastricht, and the Sultan Qaboos Univer- sity (College of Science, Earth Science Department, Al Khod) carried out field work in three areas in the Sultanate of Oman. In the Al Khod area, the Late Campanian?–Maastrichtian Al Khod Conglomerate (Nolan et al., 1990; A. S. Schulp, G. J. Boekschoten, S. S. Hanna, A. F. Hartman and J. W. M. Jagt, work in progress) was studied in detail, with the emphasis on vertebrate remains. At Jebel Rawdah, marine faunas of the Maastrichtian Simsima Formation (Kennedy, 1995; Smith, 1995; Smith et al., 1995) were sampled, while in the Saiwan area (Huqf Desert), they were collected from the Campanian Samhan Formation in which rudist reefs occur (Platel et al., 1994; Schumann, 1995). In the latter area, two localities within the Samhan Formation yielded suites of silicified ammonites (Figure 1). These specimens, together with material collected previously from Locality 1 by Alastair Milne (formerly at Petroleum Development Oman, Mutrah) and Carina Hoorn- Milne (formerly at the Sultan Qaboos University, Al Khod), are described and illustrated herein. 2. Geographic and stratigraphic setting Outcrops in the Huqf Desert south of Saiwan are well known for their rudist reefs (see e.g., Platel et al., 1994; Schumann, 1995). In this area, two localities were sampled (Figure 1): Locality 1, GPS co-ordinates (UTM 40): 562 444/ 229 4854. With the exception of SQU H-13 (Manam- bolites dandensis, Figure 6A–C), all ammonites were collected from this locality. Associated faunal ele- ments include rare rudistids, arbaciid, holectypid and spatangoid echinoids, scleractinian corals, and thick- shelled oysters conspecific with, or closely related to, Oscillopha figari (Fourtau, 1904), previously recorded from the ?Upper Campanian–Maastrichtian of Egypt and Jordan (see Malchus, 1990; Aqrabawi, 1993). Locality 2, GPS co-ordinates (UTM 40): 561 540/ 228 6646. A single specimen of M. dandensis (SQU H-13) was collected here. Lithologic logs were not measured, but the sections sampled correspond to units recognized by Platel et al. (1994) and Schumann (1995) (see Figure 2). Ammo- nites from Locality 1 all originate from Schumann’s Unit 1, which comprises yellowish white marls and marly limestones up to 12 m thick, usually intensely weathered. In the section of Platel et al. (1994, 0195–6671/00/040553+10 $35.00/0  2000 Academic Press