See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/6385893 Giant cladoxylopsid trees resolve enigma of the Earth's earliest forest stumps at Gilboa Article in Nature · May 2007 DOI: 10.1038/nature05705 · Source: PubMed CITATIONS READS 91 254 5 authors, including: Frank Mannolini Linda VanAller Hernick New York State Museum New York State Museum 8 PUBLICATIONS 160 CITATIONS 9 PUBLICATIONS 253 CITATIONS SEE PROFILE SEE PROFILE Ed Landing Christopher Berry New York State Museum Cardiff University 244 PUBLICATIONS 3,365 CITATIONS 48 PUBLICATIONS 862 CITATIONS SEE PROFILE SEE PROFILE All content following this page was uploaded by Ed Landing on 06 February 2017. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. Vol 446 | 19 April 2007 | doi:10.1038/nature05705 LETTERS Giant cladoxylopsid trees resolve the enigma of the Earth’s earliest forest stumps at Gilboa William E. Stein1, Frank Mannolini2, Linda VanAller Hernick2, Ed Landing2 & Christopher M. Berry3 The evolution of trees of modern size growing together in forests Middle Devonian (Eifelian) into the Carboniferous, were major fundamentally changed terrestrial ecosystems1–3. The oldest trees contributors to floras worldwide14. Traditionally considered inter- are often thought to be of latest Devonian age (about 380–360 Myr mediate between Lower Devonian vascular plants and ferns or old) as indicated by the widespread occurrence of Archaeopteris sphenopsids, we do not yet understand these plants well enough to (Progymnospermopsida)4. Late Middle Devonian fossil tree reconstruct their overall architecture or phylogeny accurately. Recent stumps, rooted and still in life position, discovered in the 1870s work indicates that the group may have had considerable morpho- from Gilboa, New York5, and later named Eospermatopteris,are logical and anatomical diversity. Several forms were probably quite widely cited as evidence of the Earth’s ‘oldest forest’6,7. However, large and some had significant secondary tissues15–19. Within their affinities and significance have proved to be elusive because Cladoxylopsida, the order Pseudosporochnales, represented espe- the aerial portion of the plant has been unknown until now. Here we cially by the genus Pseudosporochnus from Goe´, Belgium (latest report spectacular specimens from Schoharie County, New York, Eifelian), are among the best-studied20,21. Compressions are com- showing an intact crown belonging to the cladoxylopsid Wattieza monly found of digitately branched systems bearing sterile and (Pseudosporochnales)8 and its attachment to Eospermatopteris fertile non-laminar appendages, all having a highly distinctive trunk and base. This evidence allows the reconstruction of a tall ‘speckled’ pattern caused by sclereid nests in the cortex. On the (at least 8 m), tree-fern-like plant with a trunk bearing large bran- basis of the association of typical branches with trunk fragments, ches in longitudinal ranks. The branches were probably abscised Pseudosporochnus has been reconstructed as a small tree22. How- as frond-like modules. Lower portions of the trunk show longitud- ever, only one specimen shows direct insertion of a single fragment- inal carbonaceous strands typical of Eospermatopteris, and a flat ary branch base on the trunk. Well-defined surfaces at the proximal bottom with many small anchoring roots. These specimens pro- end of branches clearly match the regular pattern of attachment scars vide new insight into Earth’s earliest trees and forest ecosys- on the trunks. From this, regular abscission of the branches from the tems. The tree-fern-like morphology described here is the oldest trunk has been inferred22. The genus Wattieza from Belgium and example so far of an evolutionarily recurrent arborescent body Venezuela shows a similar construction of branch systems, including plan within vascular plants. Given their modular construction, probable basal abscission surfaces and speckled texture, but bears these plants probably produced abundant litter, indicating the more complex appendages, some with recurved tips bearing spor- potential for significant terrestrial carbon accumulation and a angia8. However, the trunk remains unknown. detritus-based arthropod fauna by the Middle Devonian period. The material described here is derived from a New York State Although the fossil record provides evidence of increasing size and Department of Environmental Conservation quarry on the north- complexity of plants through the Devonian, little is known about west slope of South Mountain, Schoharie County, New York how the origin of tree-sized individuals changed the evolutionary (42u 239 N, 74u 169 W). This site is located about 13 km east of the dynamics of terrestrial ecosystems. The famous ‘earliest forest’ occur- highest in situ Gilboa stump horizon at Manorkill Falls7 and lies close rence of upright and rooted sandstone casts called Eospermatopteris to inferred palaeo-shoreline23. Long-term collecting at this locality found at three stratigraphic levels (Middle Devonian, upper Givetian has produced a diverse flora24. to about the Middle/Upper Devonian boundary, about 385 Myr ago) The quarry exposes 7.5 m of rock in the Oneonta Formation, the at Gilboa, New York, displays typical difficulties encountered in lowest formation of the eastern terrestrial facies of the Genesee making morphological and ecological interpretations. Each cast, Group. Although the dating of the terrestrial sediments remains im- invariably broken 50–150 cm above the base, is typically 50–100 cm precise, palynostratigraphy of nearby samples yields latest Givetian in circumference, flaring proximally to as much as 330 cm at the to earliest Frasnian age25. The lower 3.3-m exposure includes terrest- base. A distinct pattern of longitudinally oriented carbonaceous rial red/brown siltshales, sandstones with root structures, and several strands occurs on the trunk, often showing proximal anastomosis. soil horizons. The highest soil horizon is overlain by a sandstone unit Eospermatopteris was initially thought to be associated with isolated with west-dipping foresets (3.3–6.0 m), which is consistent with a branch systems and was reconstructed as a pteridosperm (early seed small fluvial delta. Abundant plant debris occurs low in these foresets, plant)9. However, subsequent work has provided little support for including shoot systems and logs ranging from a few centimetres this reconstruction10. Thus, evidence so far allows wide latitude in to several metres in length. The logs mostly lie in near north–south phylogenetic and ecological interpretations of the plant, including orientation perpendicular to the palaeocurrent direction and parallel aneurophytalean progymnosperm11, lepidosigillarioid lycopsid1,12 or with small wave ripples. Some specimens show attachment of fine cladoxylopsid13. sterile or fertile appendages to branches. These data indicate minimal Among these possibilities, it is becoming increasingly evident that transport and rapid deposition. We describe two exceptionally com- members of the class Cladoxylopsida, ranging at least from the early plete specimens here. 1Department of Biological Sciences, Binghamton University, Binghamton, New York 13902-6000, USA. 2New York State Museum, Albany, New York 12230, USA. 3School of Earth, Ocean and Planetary Sciences, Cardiff University, Cardiff CF10 3YE, UK. 904 © 2007 Nature Publishing Group NATURE | Vol 446 | 19 April 2007 LETTERS The first (Fig. 1a, b) represents the only tree-sized member of the upper and lower counterparts showing surface features. The trunk Pseudosporochnales so far discovered with substantial connection of is more than 6 m in length, with a width of 13 cm at the top and the aerial portions of the plant. More than 2 m of trunk was found in expanding to 47 cm near the base. The top is truncated but shows an the field, of which the upper 130 cm has been recovered mostly intact. identical pattern of branch scars and speckled surface to that The trunk ranges in width from 15 cm at the top, within a well- observed about 75 cm below the crown in the first specimen defined crown region, to 18 cm at the recovered specimen’s proximal (Fig. 2a, 3a). Below this level, the trunk shows diminution of branch end. At least eight digitate branches are attached in the crown, but attachment features, as in the first specimen, replaced by a system of several more were probably attached both above and below the longitudinal coalified strands. The coalified strands are distally nar- exposed surface of the compression. The branches bear sterile and row and closely spaced, becoming larger and more separate towards fertile appendages (Fig. 1c). The appendages have a central axis the base. Near its proximal end, about 70 cm from the base of the and whorled dichotomous ultimate units. Fertile appendages bear specimen (Fig. 2a, 3b), the trunk swells to form a flattened cast (8– recurved tips bearing sporangia. These features allow identification 10 cm thick), with a change in the pattern of the longitudinal strands to Wattieza Stockmans8. Attached branches observed in face-on and indicating anastomosis. Combined evidence leaves little doubt about edge-on views seem to have been bilaterally symmetrical, giving the assignment of the specimen to Eospermatopteris. Unlike the upright plant an