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.

中文翻译：

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中泥盆纪始祖鸟的根标志着最早的化石森林发生了革命性的变化。

中泥盆纪（393-383 Ma）树木和森林的起源是地球历史的转折点，标志着陆地生态，地球化学循环，大气二氧化碳水平和气候的永久变化。但是，所有这些因素如何相互关联仍然很大程度上未知。从美国开罗附近的卡茨基尔地区的化石土壤（古土壤）中，我们报告了全世界尚未发现的最古老的森林（吉维田中部）的证据。与纽约吉尔伯（Gilboa）的著名景点相似，我们发现了像树蕨一样的Eospermatopteris（Cladoxylopsida）。但是，开罗的环境似乎一直很干燥。除了单个神秘的根系，该根系可能属于非常早期的根形的番茄红素，我们还看到了这里壮观的，广泛的根系，被分配给包含始祖鸟属的木质植物群。由于拥有多个先进特征以及与后来的优势种子植物的关系，这一群体对于随后的森林进化史显得至关重要。在这里，我们证明了始祖鸟具有非常先进的根系，基本上可以与现代种子植物媲美。这表明该群体具有独特的生态作用，涉及能源和资源利用的大大扩展，因此对全球过程的影响远大于仅从树木大小或生根深度所预期的范围。