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 CO(2), modified climate, changes in sedimentation patterns and mass extinction. 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 1920s. Hundreds of large Eospermatopteris sandstone casts, now thought to represent the bases of standing cladoxylopsid trees, 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 methods. In 2010, removal of the quarry backfill enabled reappraisal of the palaeoecology of this important site. Here we describe a 1,200 m(2) 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 environment, 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.
The origin of trees and forests in the Mid Devonian (393–383 Ma) was a turning point in Earth history, marking permanent changes to terrestrial ecology, geochemical cycles, atmospheric CO2 levels, ...and climate. However, how all these factors interrelate remains largely unknown. From a fossil soil (palaeosol) in the Catskill region near Cairo NY, USA, we report evidence of the oldest forest (mid Givetian) yet identified worldwide. Similar to the famous site at Gilboa, NY, we find treefern-like Eospermatopteris (Cladoxylopsida). However, the environment at Cairo appears to have been periodically drier. Along with a single enigmatic root system potentially belonging to a very early rhizomorphic lycopsid, we see spectacularly extensive root systems here assigned to the lignophyte group containing the genus Archaeopteris. This group appears pivotal to the subsequent evolutionary history of forests due to possession of multiple advanced features and likely relationship to subsequently dominant seed plants. Here we show that Archaeopteris had a highly advanced root system essentially comparable to modern seed plants. This suggests a unique ecological role for the group involving greatly expanded energy and resource utilization, with consequent influence on global processes much greater than expected from tree size or rooting depth alone.
•The earliest fossil forest to date is recovered from the Devonian of New York•Three types of trees are identified from fossil soil evidence in plan view•Early lignophyte relatives of seed plants have surprisingly modern root systems•Advanced energetics in this group suggests a unique role in changing Earth history
Using data from a Middle Devonian fossil soil, Stein et al. report root systems from the earliest intact forest to date, including cladoxylopsids, possibly stigmarians and Archaeopteris. Striking seed plant-like features of the latter indicate a special role for this clade in the profound changes in Earth global systems that took place at that time.
To test the extent of herbivory in early terrestrial ecosystems, we examined compression–impression specimens of the late Middle Devonian liverwort Metzgeriothallus sharonae, from the Catskill Delta ...deposit of eastern New York state. Shale fragments of field‐collected specimens were processed by applying liquid nitrocellulose on exposed surfaces. After drying, the film coatings were lifted off and mounted on microscope slides for photography. Unprocessed fragments were photographed under cedarwood oil for enhanced contrast. An extensive repertoire of arthropodan‐mediated herbivory was documented, representing three functional feeding groups and nine subordinate plant–arthropod damage types (DTs). The herbivory is the earliest occurrence of external foliage‐feeding and galling in the terrestrial fossil record. Our evidence indicates that thallus oil body cells, similar to the terpenoid‐containing oil bodies of modern liverworts, were probably involved in the chemical defence of M. sharonae against arthropod herbivores. Based on damage patterns of terrestrial plants and an accompanying but sparse body‐fossil record, Devonian arthropodan herbivores were significantly smaller compared to those of the later Palaeozoic. These data collectively suggest that a broad spectrum herbivory may have had a more important role in early terrestrial ecosystems than previously thought.
For over 150 years, the mid-Devonian Eospermatopteris stump cast localities comprising the “oldest known petrified forest” of Goldring (1927) at Gilboa, New York have rarely been accessible for ...study. In 2010–2013, we had the opportunity to appraise all three major sites. Presented here are observations focusing on botanical data that may prove useful for interpreting future sites. Eospermatopteris at Riverside Quarry consists of stem base casts/molds, and corresponding root mounds on a paleosol surface. Sizes, spatial distributions, and unusual occurrences of the root mounds are assessed. Trunks above the base are also observed as compressions showing features of outer cortex and probable vascular tissues, as interpreted from previous examples. An arboreal isoetalean is noted on the paleosol along with an enigmatic mound possibly representing a Stigmaria-like root system similar to that described at Cairo NY. Details of aneurophytalean stems on the paleosol surface are presented including evidence of attached lateral branch systems, or possible rooting structures of small size. The paleosol at Gilboa Dam is remarkably similar to that at Riverside Quarry, but with carbonaceous remains much better preserved. Eospermatopteris base casts and root mounds are present along with probable aneurophytalean stems showing abundant evidence of attached lateral branches that are themselves profusely branched. The Manorkill locality exhibits weathered Eospermatopteris casts that outcrop along a ledge offering profile views. The Gilboa localities are significant in providing probably the best botanical data on rooted and close to in place floral elements from a mid-Devonian paleosol to date.
•Historically important Catskill localities surveyed.•Spatial data from Riverside Quarry presented.•New observations from the original 1869 and Manorkill localities.•Reassessing evidence for major plant groups in mid-Devonian landscapes.
Liverworts are generally regarded as rare elements in Palaeozoic floral assemblages. However, a focus on dark gray to black shales and siltstones in the Middle–Late Devonian Catskill Delta of eastern ...New York shows that liverworts are locally quite common as well-preserved, apparently parautochthonous specimens in thin, lenticular, dark gray–black shale and siltstone lenses. These lenses are either dysoxic–anoxic lacustrine or estuarine facies deposited under oxygen-stratified water masses or rapidly deposited flood plain deposits that were not oxidized after deposition. Carbonized remains of the upper Middle Devonian (Givetian) liverwort
Metzgeriothallus sharonae sp. nov. are locally common in these lenses. Well-preserved thalli (gametophytes) are only evident by projecting polarized light on the shale and siltstone surfaces. An associated sporophyte capsule is the first evidence of a reproductive structure in a Devonian liverwort.
Metzgeriothallus sharonae sp. nov. is the oldest known liverwort. The age of the new species helps recalibrate chloroplast DNA studies that have led to proposals of the timing of liverwort diversification by showing that the evolutionary separations of the Jungermanniopsida and Marchantiopsida and of the Metzgeriidae and Jungermanniidae previously thought to be Late Devonian and Late Carboniferous, respectively were no younger than late Middle Devonian.
The charophyte flora of the Hamilton Group consists of both vegetative and reproductive organs. The external structure of Sycidium is elucidated by the discovery of antheridial shields at the surface ...of the utricle containing the oospore. The oldest representative of the genus, the Ludlowian (Upper Silurian) Sycidium siluricum (Ishchenko and Ishchenko) which presents the same complex structure, is thus featured as the oldest bisexual plant. Unknown in North America prior to the Lower Carboniferous, the discovery of Sycidium sp. 1 in the Givetian Hamilton Group provides precise evidence of the distribution of Sycidiaceae during the Middle Devonian. Besides Sycidium, the charophyte assemblage includes gyrogonites and oospores, as well as thallus remains; on the whole, the three orders of Charophyta are represented. The fine grey shales of the Plattekill Formation suggest an aquatic, non-detrital habitat, which was certainly suitable to charophyte vegetation. The preservation of delicate structures reflects an absence of transport during fossilization.
•Discovery of Devonian charophytes with both vegetative and reproductive organs•First evidence of monoecia in Sycidium showing antheridia connected to oospores•Sycidium becomes the oldest bisexual plant.•Thallus remains recall Palaeonitella as well as extant Nitelloideae.•First report of Sycidium from the Devonian of North America
The Cambrian–Ordovician boundary is a type 1 depositional sequence boundary with dramatic local erosional incision in restricted marine facies on the easternmost New York Promontory. The systemic ...boundary is bracketed below by Late Cambrian, upper Cordylodus proavus Zone (s.s). conodonts from carbonates of the upper Little Falls Formation (=Whitehall Formation, abandoned). Presumed Lower Ordovician ellesmeraceratoid cephalopods from the upper Little Falls are uppermost Cambrian and among the oldest known in North America. The overlying deepening–shoaling cycle of the Tribes Hill Formation (=Cutting and Great Meadows Formations, abandoned) is the local expression of a lowermost Ordovician (Rossodus manitouensis Zone) depositional sequence recognizable across Laurentia. Complete replacement of conodonts takes place in the late Tremadocian or Tremadocian–Arenigian boundary interval with onlap of the “Fort Ann Formation” across the paleokarst cap of the Tribes Hill. The trilobites Hystricurus sp. and Symphysurina myopia Westrop new species occur in less restricted, thrombolitic facies of the middle Tribes Hill that have the highest conodont diversity. Ulrichodina Furnish, 1938, emend. is regarded as the senior synonym of the conodont Colaptoconus Kennedy, 1994 (=GlyptoconusKennedy, 1980).
The Cambrian–Ordovician boundary is a type 1 depositional sequence boundary with dramatic local erosional incision in restricted marine facies on the easternmost New York Promontory. The systemic ...boundary is bracketed below by Late Cambrian, upper Cordylodus proavus Zone (s.s). conodonts from carbonates of the upper Little Falls Formation (=Whitehall Formation, abandoned). Presumed Lower Ordovician ellesmeraceratoid cephalopods from the upper Little Falls are uppermost Cambrian and among the oldest known in North America. The overlying deepening–shoaling cycle of the Tribes Hill Formation (=Cutting and Great Meadows Formations, abandoned) is the local expression of a lowermost Ordovician (Rossodus manitouensis Zone) depositional sequence recognizable across Laurentia. Complete replacement of conodonts takes place in the late Tremadocian or Tremadocian–Arenigian boundary interval with onlap of the “Fort Ann Formation” across the paleokarst cap of the Tribes Hill. The trilobites Hystricurus sp. and Symphysurina myopia Westrop new species occur in less restricted, thrombolitic facies of the middle Tribes Hill that have the highest conodont diversity. Ulrichodina Furnish, 1938, emend. is regarded as the senior synonym of the conodont Colaptoconus Kennedy, 1994 (=Glyptoconus Kennedy, 1980).
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