RECONSTRUCTION OF THE APPARATUS OF THE CONODONT GENERA HINDEODUS AND CAENODONTUS FROM THE HEGLER LIMESTONE MEMBER (BELL CANYON FORMATION, GUADALUPIAN, MIDDLE PERMIAN), GUADALUPE MOUNTAINS, WEST TEXAS

A 38 m section of the Hegler and Pinery Members of the Bell Canyon Formation (Guadalupian, Middle Permian) exposed on the north side of US 62/180 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 4 m of sandstone topped by a thin sandy bentonite overlain by two carbonate mudstone units (Hegler Limestone Member) separated by a one meter thick sandstone interval. These limestone beds contain seven genera of agglutinated foraminifers and the conodonts Pseudohindeodus ramovsi and Caenodontus serrulatus. 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 belonging to the upper part of the Hegler Limestone Member and bearing ammonoids. Above the ammonoid beds is a 6 m silty interval with several thin limestone beds containing agglutinated foraminifers, the conodonts P. ramovsi, Jinogondolella aserrata, Hindeodus sp., and rare radiolarians. The remainder of the section contains two carbonate dominated intervals referred to the lower and upper parts of the Pinery Limestone Member (separated by a sandstone interval). In one sample (7G) of the lowermost carbonate of the Hegler Limestone Member, abundant elements of P. ramovsi and scarce elements of C. serrulatus were recovered enabling the complete apparatus of each of these species to be constructed. The apparatus of P. ramovsi is very similar to the septimembrate (15 elements) apparatus of Idiognathodus/Streptognathodus and contains two paired P1 and P2 elements, an S0 element flanked by paired S1-S4 elements, and paired M elements. One significant difference is that the paired P2 elements are not of typical ozarkodinid type. The apparatus of C. serrulatus contains paired cone shaped P1 and P2 elements, an S0 element flanked by serrated on concave side S1-S3 elements, and paired M elements. Coniform conodonts are rarely known above the Devonian and this apparatus reconstruction is the first proposed for this unique Middle Permian age coniform conodont.