Rapid Spread of Land Plants in Late Ordovician Time Altered the Composition of the Atmosphere, Climate, and Carbon/Phosphorus Burial Ratios in Marine Sediments

     Researchers at the Institute of Geology and Geophysics of the Chinese Academy of Sciences (CAS) in collaboration with Yale University, the University of Exeter, the University of Leeds, the University of Science and Technology of China, and the CAS Institute of Vertebrate Paleontology and Paleoanthropology, believe they have found a solid proxy for the initial spread of land plants in the late Ordovician period about 455 million years ago. This is earlier than previously estimated. Their findings are published in Nature Ecology & Evolution.

     Compared to marine organisms, land plants generate organic matter with higher organic carbon-to-phosphorus ratios. That organic matter from land plants eventually made its way to be deposited and buried in marine sediments. The researchers examined the rock column and found where rocks appeared with higher carbon-to-phosphorus ratios to infer when the proliferation of land plants began. Those rocks were dated to be 455 million years old.

               According to Phys/org:

“Mixing model results further reveal that since the Late Ordovician, terrestrial organic carbon has accounted for about 42 ± 15% of the total organic carbon buried in marine sediments—a figure comparable to modern values (30–57%). Paleocontinental analysis suggests land plant expansion may have occurred earlier on the Laurentian continent.”

     The researchers also found evidence that, in addition to higher carbon-to-phosphorus ratios in buried sediments, the total amount of global carbon buried also increased. This would be expected to increase atmospheric oxygen through increasing occurrences of photosynthesis.

“Elevated organic carbon burial would have spurred atmospheric oxygen accumulation while lowering atmospheric carbon dioxide levels. These effects may have been amplified by intensified silicate and phosphorus weathering associated with the rapid colonization of land by plants.”

“Collectively, these processes demonstrate that the earliest emergence and expansion of land plants likely played a pivotal role in driving Earth's surface oxygenation and climatic change. Their spread may have contributed to the Late Ordovician glaciation and indirectly influenced the mass extinction events of this period.”

    

 

 

References:

 

Land plants began reshaping Earth 455 million years ago, scientists discover. Li Yali. Phys.org. February 25, 2026. Land plants began reshaping Earth 455 million years ago, scientists discover

Carbon/phosphorus burial ratio reveals a rapid spread of land plants during the Late Ordovician. Jiachen Cai, Lidya G. Tarhan, Timothy M. Lenton, Ruoyuan Qiu, Caroline L. Peacock, Noah J. Planavsky, Pengcheng Ju, Wenjin Zhao, Zhifang Xu, Hui Zhang & Mingyu Zhao. Nature Ecology & Evolution. volume 10, pages 652–661 (February 2026). Carbon/phosphorus burial ratio reveals a rapid spread of land plants during the Late Ordovician | Nature Ecology & Evolution