A new early Smithian ammonoid fauna from the Salt Range (Pakistan)
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A new early Smithian ammonoid fauna from the Salt Range (Pakistan) Thomas Bru¨hwiler • Hugo Bucher • Ghazala Roohi • Aamir Yaseen • Khalil Rehman
Received: 27 December 2010 / Accepted: 25 May 2011 / Published online: 11 June 2011 Ó Akademie der Naturwissenschaften Schweiz (SCNAT) 2011
Abstract Recent extensive investigations in the Salt Range (Pakistan) yielded abundant, well-preserved ammonoid faunas of earliest to latest Smithian age that provided the basis for a major revision of Smithian ammonoid taxonomy and for the establishment of a high-resolution biostratigraphic sequence. Here, an additional new ammonoid fauna of typical early Smithian affinity from the uppermost part of the Ceratite Sandstone of the Nammal Gorge section is described. The new fauna, termed Euflemingites cirratus beds, is bracketed between the underlying early Smithian ‘‘Flemingites flemingianus beds’’, here renamed Clypeoceras superbum beds, and the overlying middle Smithian Brayardites compressus beds. Comparison with a recently published high-resolution biochronological scheme for the Smithian of the NIM (northern Indian Margin) based on the Salt Range, Spiti (Himachal Pradesh, northern India) and Tulong (South Tibet) basins shows that the Euflemigites cirratus fauna correlates with the Dieneroceras beds from Spiti based on the common occurrence of the ammonoid species Kraffticeras pseudoplanulatum. The transT. Bru¨hwiler (&) H. Bucher Pala¨ontologisches Institut und Museum der Universita¨t Zu¨rich, Karl Schmid-Strasse 4, 8006 Zurich, Switzerland e-mail: [email protected] H. Bucher e-mail: [email protected] G. Roohi A. Yaseen K. Rehman Earth Science Division, Pakistan Museum of Natural History, Garden Avenue, Shakarparian, Islamabad 44000, Pakistan e-mail: [email protected] A. Yaseen e-mail: [email protected] K. Rehman e-mail: [email protected]
panthalassic biogeographical distribution of Euflemingites cirratus allows correlating the new ammonoid fauna with part of the Meekoceras gracilitatis ammonoid zone of western USA. Three new species (Kashmirites weisserti, Arctoceras schalteggeri and Vercherites wyleri) are described. Keywords Ammonoidea Early Triassic Smithian Salt Range Pakistan Biostratigraphy
Introduction Since the late nineteenth century, the Salt Range in Pakistan has been a classic locality for the research on Early Triassic ammonoids thanks to the pioneering contribution of Waagen (1895). Recent extensive investigations in the Salt Range have yielded abundant, well-preserved ammonoid faunas of earliest to latest Smithian age (Bru¨hwiler et al. 2011b). This newly collected material provided the basis for a profound revision of the taxonomy of Smithian ammonoids. It also enabled the establishment of a much higher-resolution biostratigraphic sequence for the Smithian of the Salt Range in comparison with previous ammonoid zonations for this area (Mojsisovics et al. 1895; Waagen 1895; Frech 1905; Guex 1978). The biochronological treatment of these data together with those from two
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