BIOSTRATIGRAPHY OF A COMPLETE PINERY SECTION (BELL CANYON FORMATION, GUADALUPIAN, MIDDLE PERMIAN), GUADALUPE MOUNTAINS, WEST TEXAS

A 38 m section of the Hegler and Pinery Members (Bell Canyon Formation, Middle Permian, Guadalupian) exposed on the north side of US 180/62 a few kilometers west of its intersection with TX 54 on the west side of the Guadalupe Mountains contains limestone intervals interbedded with sandstone and siltstone. The basal interval consists of four meters of sandstone topped by a thin sandy bentonite overlain by two limestone units separated by a one meter thick sandstone interval. These limestone beds contain agglutinated foraminifers of the genera Psammosphaera, Thurammina, Hyperammina, Ammodiscillites, Ammobaculites, Textularia, Reophax, and the conodont Pseudohindeodus ramovsi. In the middle part of the second carbonate the conodonts Jinogondolella aserrata and a narrow morphotype of J. nankingensis appear. At the top of this unit there are two nodular beds bearing ammonoids. Above the ammonoid beds is a 6 m silty interval with thin limestone beds containing agglutinated foraminifers, the conodont P. ramovsi and rare radiolarians Entactinia parapycnoclada and Hegleria mammifera. Above this is a 5 m interval dominated by limestone with subordinate silty beds. These limestone beds contain the conodonts Jinogondolella aserrata, J. palmata, calcareous foraminifers and the radiolarians Pseudoalbaillella, Entactinia, Wuyia, Polyedroentactinia, Paratriposphaera, Tormentum and the species Follicucullus japonicus. Next above is a sand/silt interval approximately 5.5 m thick topped by a unit 8 m thick of alternating limestone and siltstone with the conodonts J. aserrata, J. palmata, Pseudohindeodus sp, Hindeodus wordensis and Sweetina triticum, foraminifers, and radiolarians in the lower part including Pseudoalbaillella scalprata. The diagnostic conodont Jinogondolella postserrata first appears 1.5 m below the top of this last limestone unit and marks the Wordian/Capitanian boundary. This section also contains a diverse fish assemblage represented by chondrichthyan teeth, scales and buccopharyngeal denticles; actinopterygian teeth, tooth plates, scales and pharyngeal denticles. A new genus of the Jalodontidae and the species Stethacanthulus meccaensis were also found and are the youngest known occurrences of these taxa in the world.