T173 High-Resolution Investigations of the Permian-Triassic Transition (Posters)

Monday, 23 October 2017
9:00 AM - 6:30 PM
Halls 4EF

REVISED CLARKINA TAXONOMY BASED ON CONODONT SAMPLE-POPULATION APPROACH

Paper number: T173-1
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

A high-resolution Lopingian conodont biostratigraphic framework is necessary to resolve event correlation leading to the end-Permian mass extinction. This has been established in South China using a sample-population approach. Two different approaches, form species and sample-population species, have been used to identify species. The first method has been used from the beginning of conodont research; it identifies species based on one or two characters in a single or a few specimens. This method was popular for a long time because conodont animals were unknown and only a few specimens were obtained from rock samples. Abundant conodont specimens are now often recovered from a rock sample. Abundant specimens in a sample show morphologic gradations that lead us to conclude some form species are better referred to a single species. Many form species are often recognized in single samples making it difficult to stably identify species and a disadvantage to meeting requirements for high-resolution conodont biostratigraphy. The second approach was first mentioned in 1979 to identify ‘neogondolellids’ because the taxa show considerable morphologic variability. “Sample-populations” were formally adopted in 2004 for Clarkina to define the base Changhsingian, resulting in the stable definition, recognition and correlation of C. wangi. Four key points should be emphasized: 1) the method recognizes the entire sample population, including representatives of ontogenetic stages from juvenile to gerontic; 2) intraspecific variations in the shape of the segminiplanate element within a sample population are expected; 3) variation in platform shape of the same growth stage, and variations throughout ontogeny are important in a sample; 4) more than one population may be present in a sample. Yuan et al. (2014, 2017) used this approach to revise the Lopingian Clarkina taxonomy and succession of South China.

Yuan, D.X., Shen, S.Z., Henderson, C.M., Chen, J., Zhang, H., Feng, H.Z., 2014. Revised conodont-based integrated high-resolution timescale for the Changhsingian Stage and end-Permian extinction interval at the Meishan sections, South China. Lithos, 204: 220-245.

Yuan, D.X., Shen, S.Z., Henderson, C.M., 2017. Revised Wuchiapingian conodont taxonomy and succession of South China. Journal of Paleontology, 91: in press.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-300957

© Copyright 2017 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.