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Anatomically Preserved “Strobili” and Leaves from the Permian of China (Dorsalistachyaceae, Fam

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Anatomically Preserved “Strobili” and Leaves from the Permian of China (Dorsalistachyaceae, Fam Anatomically preserved "strobili" and leaves from the Permian of China (Dorsalistachyaceae, fam. nov.) broaden knowledge of Noeggerathiales and constrain their possible taxonomic affinities Wang, Shi-Jun; Bateman, Richard M.; Spencer, Alan R.t.; Wang, Jun; Shao, Longyi; Hilton, Jason DOI: 10.3732/ajb.1600371 License: Creative Commons: Attribution-NonCommercial (CC BY-NC) Document Version Publisher's PDF, also known as Version of record Citation for published version (Harvard): Wang, S-J, Bateman, RM, Spencer, ART, Wang, J, Shao, L & Hilton, J 2017, 'Anatomically preserved "strobili" and leaves from the Permian of China (Dorsalistachyaceae, fam. nov.) broaden knowledge of Noeggerathiales and constrain their possible taxonomic affinities', American Journal of Botany, vol. 104, no. 1, pp. 127-149. https://doi.org/10.3732/ajb.1600371 Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. •Users may freely distribute the URL that is used to identify this publication. •Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. •User may use extracts from the document in line with the concept of ‘fair dealing’ under the Copyright, Designs and Patents Act 1988 (?) •Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive. If you believe that this is the case for this document, please contact [email protected] providing details and we will remove access to the work immediately and investigate. Download date: 01. Feb. 2019 RESEARCH ARTICLE AMERICAN JOURNAL OF BOTANY Anatomically preserved “strobili” and leaves from the Permian of China (Dorsalistachyaceae, fam. nov.) broaden knowledge of Noeggerathiales and constrain their possible taxonomic affi nities 1 Shi-Jun Wang2 , Richard M. Bateman3 , Alan R. T. Spencer 4 , Jun Wang 5 , Longyi Shao 6 , and Jason Hilton 7,8 PREMISE OF THE STUDY: Noeggerathiales are an extinct group of heterosporous shrubs and trees that were widespread and diverse during the Pennsylvanian– Permian Epochs (323–252 Ma) but are of controversial taxonomic affi nity. Groups proposed as close relatives include leptosporangiate ferns, sphenopsids, progymnosperms, or the extant eusporangiate fern Tmesipteris . Previously identifi ed noeggerathialeans lacked anatomical preservation, limiting taxo- nomic comparisons to their external morphology and spore structure. We here document from the upper Permian of China the fi rst anatomically pre- served noeggerathialeans, which enhance the perceived distinctiveness of the group and better indicate its systematic affi nity. METHODS: We describe in detail the newly discovered, anatomically preserved heterosporous strobilus Dorsalistachya quadrisegmentorum , gen. et sp. nov., and redescribe its suspected foliar correlate, the pinnate leaf Plagiozamites oblongifolius . KEY RESULTS: Plagiozamites possesses an omega ( Ω )-shaped vascular trace and prominent cortical secretory cavities—a distinctive anatomical organiza- tion that is echoed in the newly discovered strobili. Dorsalistachya strobili bear highly dissected sporophylls alternately in two vertical rows, suggesting that they are homologs of leaf pinnae. If so, the “strobilus” is strictly a pseudostrobilus and consists of sporangium-bearing units that are one hierarchical level below true sporophylls. The “sporophylls” bear four microsporangia on the lower (abaxial) surface, occasionally interspersed with short longitudi- nal rows of megasporangia. A single functional megaspore develops within each winged megasporangium, suggesting adaptation for dispersal as a single unit. CONCLUSIONS: Dorsalistachya presents a unique combination of reproductive features that amply justifi es establishment of a new family, Dorsalistachyaceae. Noeg- gerathiales represent a distinct taxonomic Order of free-sporing plants that most resembles early-divergent eusporangiate ferns and the more derived among the extinct progymnosperms. By the early Permian, noeggerathialeans had attained levels of reproductive sophistication similar to the most derived among the Pa- leozoic sphenophytes and lycophytes, but their heterosporous life history may have contributed to their extinction during the Triassic climatic aridifi cation. KEY WORDS 3D reconstruction; Dorsalistachya ; Dorsalistachyaceae; eusporangiate fern; heterospory; Noeggerathiales; paleobotany; Permian; phylogeny; progymnosperm; Xuanwei Formation 1 Manuscript received 18 October 2016; revision accepted 22 November 2016. Approximately half of the major groups of land-plants recognized 2 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese today have left no close living relatives (e.g., Hilton and Bateman, Academy of Sciences, Xiangshan, Beijing 100093, P. R. China; 2006 ). However, gradually characterizing such groups until they 3 Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3DS, UK; can take their place in rigorous evolutionary studies requires pains- 4 Department of Earth Sciences and Engineering, Imperial College London, London, SW7 taking paleobotanical research, building conceptual whole-plants 2BP, UK; 5 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and from exceptionally preserved examples of their component organs Palaeontology, Chinese Academy of Sciences, Nanjing 210008, P. R. China; ( Bateman and Hilton, 2009 ). Our knowledge of land-plant phylog- 6 State Key Laboratory of Coal Resources and Safe Mining, School of Geosciences and Surveying eny would remain rudimentary even today if paleobotanists had Engineering, China University of Mining and Technology, Beijing 100083, P. R. China; and not recognized and circumscribed fossil groups that provide phylo- 7 Birmingham Institute of Forestry Research & School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK genetic bridges between extant groups (e.g., Taylor et al., 2009 ): rhynio- 8 Author for correspondence (e-mail: [email protected]) phytes linking bryophytes with lycophytes, progymnosperms linking doi:10.3732/ajb.1600371 ferns with seed-plants, and—within seed-plants—pteridosperms AMERICAN JOURNAL OF BOTANY 104 (1): 127 – 149 , 2017; http://www.amjbot.org/ © 2017 Wang et al. Published by the Botanical Society of America. This work is licensed under a Creative Commons Attribution License (CC-BY-NC). • 127 128 • AMERICAN JOURNAL OF BOTANY linking several disparate groups of extant gymnosperms and the angiosperms. One major group that, until now, has evaded such confi dent phylogenetic placement is the Noeggerathiales sensu Němejc, 1931 (= Noeggerathiopsida sensu Boureau, 1964 ); a group for which we suggest the colloquial name 'bottle-brush ferns'. Extending from the Mississippian to the Triassic, noeggerathia- lean fossils are a particularly important component of peat-forming plant communities in the Permian fossil fl oras of China ( Wang et al., 2009 , 2012 ). Recent research on in situ fossil forests has reconstructed members of the Noeggerathiales as fern-like trees that produced a dense crown of fern-/cycad-like leaves and elongate strobili of crowded sporophylls ( Wang et al., 2009 ; Wang et al., 2012). Although these investigations provided important information on the growth archi- tecture of members of the Noeggerathiales, the absence of anatomically preserved fossils precluded detailed comparison with other phyloge- netically important plant groups. Consequently, noeggerathialeans have long been a ‘phylogenetic football’; they have been linked with an extraordinarily wide range of major groups, including leptospo- rangiate ferns ( Němejc, 1931 ), sphenopsids ( Browne, 1933 ), pro- gymnosperms ( Beck, 1976 , 1981 ; Meyen, 1987 ; Taylor et al., 2009 ), or ranked alongside these clades as a distinct group in its own right ( Boureau, 1964 ); comparison has even been made with the primitive extant eusporangiate fern Tmesipteris Bernh. ( Bierhorst, 1971 ). Here, we document for the fi rst time anatomically preserved noeggerathialean leaves, rachises, and strobili, whose spatial juxta- position and anatomical similarity together suggest that they repre- sent diff erent parts of the same whole-plant species ( Bateman and Hilton, 2009 ). Th e diffi culty that we have experienced in placing taxonomically these morphologically disparate organs prompts a broader review of the classifi cation and potential evolutionary sig- nifi cance of Noeggerathiales. MATERIALS AND METHODS FIGURE 1 Location of Huopu coal mine. (A) Outline map of China show- Geological context— Th e plant fossils described here were found in ing provincial boundaries; boxed area enlarged in (B) . (B) The location of Guizhou Province, southwestern China ( Wang et al.,
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