Surprisingly complex community discovered in the mid-Devonian fossil forest at Gilboa

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The origin of trees by the mid-Devonian epoch (398–385 million years ago) signals a major change in terrestrial ecosystems with potential long-term consequences including increased weathering, drop in atmospheric CO2, modified climate, changes in sedimentation patterns and mass extinction1, 2, 3. However, little is known about the ecology of early forests or how changes in early terrestrial ecosystems influenced global processes. One of the most famous palaeontological records for this time is the ‘oldest fossil forest’ at Riverside Quarry, Gilboa, New York, USA, discovered in the 1920s4, 5. Hundreds of large Eospermatopteris sandstone casts, now thought to represent the bases of standing cladoxylopsid trees6, were recovered from a horizon that was originally interpreted as a muddy swamp. After quarry operations ceased, relatively minor outcrops of similar fossils at nearby localities have provided limited opportunities to evaluate this pervasive view using modern methods7, 8. In 2010, removal of the quarry backfill enabled reappraisal of the palaeoecology of this important site. Here we describe a 1,200m2 map showing numerous Eospermatopteris root systems in life position within a mixed-age stand of trees. Unexpectedly, large woody rhizomes with adventitious roots and aerial branch systems identified as aneurophytalean progymnosperms run between, and probably climb into, Eospermatopteris trees. We describe the overall habit for these surprisingly large aneurophytaleans, the earliest fossil group having wood produced by a bifacial vascular cambium. The site also provides evidence for arborescence within lycopsids, extending the North American range for trees in this ecologically critical group. The rooting horizon is a dark grey sandy mudstone showing limited root penetration. Although clearly belonging to a wetland coastal plain environment9, the forest was probably limited in duration and subject to periodic disturbance. These observations provide fundamental clarification of the palaeoecology of this mixed-group early forest, with important implications for interpreting coeval assemblage data worldwide.

At a glance


  1. Eospermatopteris cast, moulds and root system, Riverside Quarry, New York, USA.
    Figure 1: Eospermatopteris cast, moulds and root system, Riverside Quarry, New York, USA.

    a, Mould in quarry highwall showing casting sandstone (black arrow) and the vertical extent of rooted palaeosol (white arrows) with both levels containing attached roots. Scale bar, 20cm. b, Bottom of newly recovered cast with attached roots diverging into casing sandstone (arrow; New York State Museum (NYSM) 18055). Scale bar, 20cm. c, Forest palaeosol horizon on quarry floor showing raised rim, central basin and extensive rooting system; the surface equivalent to the counterpart of the cast shown in b. Entire scale bar, 50cm.

  2. Plan map of part of the quarry floor showing original rooting horizon.
    Figure 2: Plan map of part of the quarry floor showing original rooting horizon.

    Eospermatopteris root mounds indicated with different levels of confidence. Dark shading, high confidence; light shading, intermediate confidence; dashed circles with no shading, low confidence. Radiating lines, radiating pattern of roots associated with root mound; central double circle, approximate diameter of central basin; outer circle, entire diameter of observed root system. Aneurophytalean main stems and other linear stem fragments are shown in black. Lycopsid main stem (arrow j) and probable distal branches (arrow k) are grey. The approximate position of the quarry highwall is indicated by a dotted line; the georeference point (see Supplementary Discussion) is indicated by a four-point star. Arrows a–l, plants that are shown in Figures or in the Supplementary Information.

  3. Aneurophytalean rhizomes.
    Figure 3: Aneurophytalean rhizomes.

    a, Large specimen showing abundant carbon and several depressions, or knobs partially permineralized with pyrite. White line, part of the grid system for the map constructed in the field. Scale, 5cm. b, Rhizome collected by Goldring (NYSM 6575) showing numerous attached roots. Scale bar, 10cm. c, Transverse section of branch base showing primary xylem, secondary xylem, secondary phloem and remnants of cortex (arrows), all embedded in extensive secondary xylem of the main stem (NYSM 18056). Scale bar, 1mm. d, Interpretation of the lateral branch xylem in c showing probable three-ribbed primary xylem (shaded). e, Interpretation of rhizome originally collected by Goldring (NYSM 18051), showing attached and associated aerial branches in outline, attached roots in black and thick carbon on rhizome in grey.

  4. Arborescent lycopsid.
    Figure 4: Arborescent lycopsid.

    Upper portion of tree (arrow k in Fig. 2), including the main stem (occupying the width between the arrows) and smaller stems with similar leaf bases that probably represent distal portions of the main stem or lateral branches (NYSM 18053). Scale bar, 10cm.


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Author information


  1. Department of Biological Sciences, Binghamton University, New York 13902-6000, USA

    • William E. Stein
  2. School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3YE, UK

    • Christopher M. Berry
  3. New York State Museum, Albany, New York 12230, USA

    • Linda VanAller Hernick &
    • Frank Mannolini


L.V.H. and F. M. were responsible for collections and analysis, W.E.S. for mapping, C.M.B. for geological section, and W.E.S. and C.M.B. for palaeoecological interpretation. W.E.S. led the writing of the paper with substantial contributions from C.M.B.

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Supplementary information

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  1. Supplementary Information (10.1M)

    This file contains a Supplementary Discussion comprising: Survey data and site comparison; Geology, palaeoenvironmental setting and age; Use of names for the fossil remains; Criteria for recognizing Eospermatopteris root systems; Difficulties in estimating height for Eospermatopteris trees; Identity of aneurophytaleans at Gilboa; Aneurophytalean rhizome compression collected by Goldring; The arborescent lycopsid at Gilboa and Supplementary References. Supplementary Figures 1-27 with legends are also included.

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