Brian F. Glenister

Permian cephalopod limestones, Oman Mountains : evidence for a Permian seaway along the northern margin of Gondwana

Abstract Cephalopod limestones of Middle Permian (Middle Guadalupian, Wordian Stage) age occur at the base of the Hawasina nappes in the Oman Mountains. They overlie mafic volcanic rocks, are a few meters thick, are interbedded locally with reef-derived gravity flow deposits. The cephalopod limestones are interpreted as a condensed sequence caused by a regional transgression on the Arabian platform. The ammonoid fauna is remarkably similar to that of the western Mediterranean and Timor, suggesting an unrestricted faunal exchange in a Permian seaway along the northern margin of Gondwana where pelagic sediments were being deposited. Due to the uncertain provenance of the Cimmerian microcontinents, the width of this seaway must remain speculative.

Ammonoid cephalopods from the Lower Permian of Thailand

The purpose of the present statement is to announce discovery of a well-preserved and potentially diverse Lower Permian ammonoid fauna from south-central Thailand. Previous Thai records of Permian ammonoids lack descriptive detail (e.g., Yanagida, 1988), but two sparse Permian occurrences from nearby areas in Malaysia have been described recently by Lee (1980). Closest similarities of the Thai material are with faunas from the Pamir (Leonova and Dmitriev, 1989) and with our undescribed collections from south Xinjiang.

Late Permian ammonoid cephalopod Cyclolobus from Western Australia

A single specimen of Cyclolobus persulcatus Rothpletz (1892), a species interpreted as a primitive member of the genus, is described from the Cherrabun Member of the Hardman Formation, Liveringa Group, Canning Basin, Western Australia. It is the youngest Permian ammonoid known from Australia. Type and other representatives of C. persulcatus from Indonesia (Timor) are part of the “Amarassi fauna,” which is considered post-Guadalupian. Cyclolobus is sporadically abundant and widely distributed in the Dzhulfian Stage, and probably extends into the overlying Dorashamian Stage.

Permian Ammonoid Cyclolobus from the Zewan Formation, Guryul Ravine, Kashmir

Ammonoid cephalopods serve significantly as a basis for correlation of strata near the boundary between the Paleozoic and Mesozoic Erathems. This is a report of the diagnostically Late Permian (uppermost Paleozoic) ammonoid Cyclolobus walkeri (Diener, 1903) from the Zewan Formation 20 meters below the Permian-Triassic contact at the classic section in Guryul Ravine, Srinagar region, Kashmir.

ENDEMIC PERMIAN AMMONOID GENUS YINOCERAS, CENTRAL HUNAN, SOUTH CHINA

Abstract Revision and redefinition of the Permian ammonoid genus Yinoceras Chao, 1954, is based upon examination of the holotype of its type species, Y. lenticulare Chao, plus new material collected from the Kungurian Dangchong Formation of central Hunan, China. Yinoceras is a valid yinoceratin genus within the pseudohaloritid Superfamily Pseudohaloritoidea, Suborder Tornoceratina, Order Goniatitida.

PAEDOPRONORITES, A NEW UPPER PERMIAN (WUCHIAPINGIAN) AMMONOID FROM INDONESIA (TIMOR)

Representatives of the ammonoid family Pronoritidae are ancestral medlicottioideans (Order Prolecanitida) characterized by moderately evolute conch and relatively simple sutures. They comprise the ancestral Pronoritinae, characterized by an undivided dorsal lobe, and the descendant Neopronoritinae with bidentate dorsal lobe. The new genus Paedopronorites is interpreted as the terminal neopronoritin paedomorph. It conforms to the pattern displayed by many late Paleozoic taxa (Glenister and Furnish, 1988a, 1988b), being the geologically youngest representative in the lineage, and characterized by small size, sutural simplification, and low abundance. Pronoritidae form one of the longer lineages of Paleozoic ammonoids, with few changes occurring from Mississippian (lower Visean) to …