Molecular signatures of fossil leaves provide unexpected new evidence for extinct plant relationships

  • Nature Ecology & Evolution 110931099 (2017)
  • doi:10.1038/s41559-017-0224-5
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Gene sequences form the primary basis for understanding the relationships among extant plant groups, but genetic data are unavailable from fossils to evaluate the affinities of extinct taxa. Here we show that geothermally resistant fossil cuticles of seed-bearing plants, analysed with Fourier transform infrared (FTIR) spectroscopy and hierarchical cluster analysis (HCA), retain biomolecular suites that consistently distinguish major taxa even after experiencing different diagenetic histories. Our results reveal that similarities between the cuticular biochemical signatures of major plant groups (extant and fossil) are mostly consistent with recent phylogenetic hypotheses based on molecular and morphological data. Our novel chemotaxonomic data also support the hypothesis that the extinct Nilssoniales and Bennettitales are closely allied, but only distantly related to Cycadales. The chemical signature of the cuticle of Czekanowskia (Leptostrobales) is strongly similar to that of Ginkgo leaves and supports a close evolutionary relationship between these groups. Finally, our results also reveal that the extinct putative araucariacean, Allocladus, when analysed through HCA, is grouped closer to Ginkgoales than to conifers. Thus, in the absence of modern relatives yielding molecular information, FTIR spectroscopy provides valuable proxy biochemical data complementing morphological characters to distinguish fossil taxa and to help elucidate extinct plant relationships.

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This research was financially supported by grants from Lund University, faculty funding for synchrotron-light-related projects for ESS and MAX IV to V.V., the Swedish Research Council (VR grant 2015-4264 to V.V., and VR grant 2014-5234 to S.M.), This research was further funded by the Swedish Research Council (VR) under grant LUCCI (Lund University Carbon Cycle Centre) and the Utrecht Network Young researchers’ grant to M.P. We thank the Botanical Garden of Lund University, Sweden for giving permission to sample plant leaves; M. Pole (Nanjing Institute of Geology and Paleontology, Nanjing, China) for providing fossil cuticles from New Zealand and Svend Visby Funder (Centre for GeoGenetics, Natural History Museum, Copenhagen, Denmark) for giving access to T. M. Harris’ fossil collections.

Author information


  1. Department of Palaeobiology, Swedish Museum of Natural History, SE-104 05, Stockholm, Sweden

    • Vivi Vajda
    •  & Stephen McLoughlin
  2. Department of Geology, Lund University, SE-223 62, Lund, Sweden

    • Vivi Vajda
  3. Department of General Physics and Spectroscopy, Vilnius University, LT-102 57, Vilnius, Lithuania

    • Milda Pucetaite
  4. MAX-IV laboratory, Lund University, SE-221 00, Lund, Sweden

    • Anders Engdahl
    •  & Jimmy Heimdal
  5. Chemical Physics, Department of Chemistry, Lund University, SE-222 41, Lund, Sweden

    • Per Uvdal


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V.V. and P.U. conceived and led the project, V.V. and S.M. recovered and prepared fossil cuticles, V.V. collected the modern cuticles. M.P., V.V. and A.E. carried out FTIR spectroscopy measurements, A.E., P.U. and J.H. provided expertise in infrared spectroscopy. Spectral analysis was performed by M.P., P.U. and J.H.S. All authors contributed to writing the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Vivi Vajda or Per Uvdal.

Supplementary information

  1. 1.

    Supplementary Information

    1 Supplementary Table, 4 Supplementary Figures, Supplementary References and Supplementary details of analysis