Department of Biological Sciences, Binghamton University, New York, NY 13902-6000, USA.
Nature. 2012 Feb 29;483(7387):78-81. doi: 10.1038/nature10819.
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.
树木起源于中泥盆世（3.98-3.85 亿年前），标志着陆地生态系统发生了重大变化，可能带来长期影响，包括风化作用增强、大气 CO2 下降、气候改变、沉积模式变化和大规模灭绝。然而，人们对早期森林的生态或早期陆地生态系统的变化如何影响全球过程知之甚少。这个时期最著名的古生物学记录之一是美国纽约吉尔博亚河滨采石场的“最古老化石森林”，该采石场于 20 世纪 20 年代被发现。从最初被解释为泥泞沼泽的一个层位中回收了数百个大型 Eospermatopteris 砂岩铸型，现在被认为代表了直立木贼类树木的基部。采石作业停止后，附近类似化石的相对较小露头提供了使用现代方法评估这一普遍观点的有限机会。2010 年，采石场回填物的清除使这个重要地点的古生态学得以重新评估。在这里，我们描述了一张 1200 平方米的地图，展示了在一个混合年龄树木群中，许多 Eospermatopteris 根系处于生命位置。出乎意料的是，带有不定根和气生树枝系统的大型木质根茎被鉴定为 aneurophytalean 原种子植物，它们在 Eospermatopteris 树木之间延伸，并可能爬入 Eospermatopteris 树木中。我们描述了这些令人惊讶的大型 aneurophytalean 的总体习性，它们是最早具有由双面向血管形成层产生的木材的化石群。该遗址还为石松类植物的分枝提供了证据，将北美树木的生态关键群的范围扩大。生根层是一层深灰色的砂质泥岩，显示出有限的根系穿透。尽管该森林显然属于湿地沿海平原环境，但它的持续时间可能有限，且受到周期性干扰。这些观察结果为混合组早期森林的古生态学提供了基本的澄清，对解释全球同期组合数据具有重要意义。
