Skip to content Skip to navigation

Article: Could land‐based early photosynthesizing ecosystems have bioengineered the planet in mid‐Palaeozoic times?

Palaeontology - Vol. 58 Part 5 - Cover Image
Publication: Palaeontology
Volume: 58
Part: 5
Publication Date: September 2015
Page(s): 803 837
Author(s): Dianne Edwards, Lesley Cherns, and John A. Raven
Addition Information

How to Cite

EDWARDS, D., CHERNS, L., RAVEN, J.A. 2015. Could land‐based early photosynthesizing ecosystems have bioengineered the planet in mid‐Palaeozoic times?. Palaeontology, 58, 5, 803-837. DOI: 10.1111/pala.12187

Author Information

  • Dianne Edwards - Cardiff University School of Earth and Ocean Sciences Cardiff UK (Email:
  • Lesley Cherns - Cardiff University School of Earth and Ocean Sciences Cardiff UK (Email:
  • John A. Raven - University of Dundee at the James Hutton Institute Division of Plant Sciences Invergowrie Dundee UK (Email:
  • John A. Raven - University of Western Australia School of Plant Biology Crawley WA Australia

Publication History

  • Issue published online: 28 August 2015
  • Article first published online: 01 January 1970
  • Manuscript Accepted: 24 June 2015
  • Manuscript Received: 01 April 2015

Funded By

Leverhulme Trust and the Gatsby Charitable Foundation

Online Version Hosted By

Wiley Online Library
Get Article: Wiley Online Library [Pay-to-View Access] |


The Ordovician and Silurian periods were times of major geological activity as regards palaeogeography, volcanism and climate change, the last of these evidenced by a series of cooling episodes and glaciations that climaxed in the Hirnantian (Late Ordovician). The presence of cryptospores in the Darriwilian (Middle Ordovician) marked the advent of higher plants on land. A critical survey of direct (mega‐ and microfossils) and some indirect evidence in succeeding rocks indicates the presence of algae, Bacteria, Cyanobacteria, Fungi, probable lichens, cryptophytes and basal tracheophytes. Similar associations of photosynthesizers and decomposers occur today in cryptogamic covers (CCs), for example biological crusts, except that bryophytes replace cryptophytes (basal embryophytes) and tracheophytes are absent. Thus, extant CCs, which make significant contributions today to global carbon and nitrogen fixation and prevention of erosion, provide an excellent analogue for the impacts of early land vegetation on both lithosphere and atmosphere. As a prerequisite to assessing impacts in Ordovician–Silurian times, with particular consideration of parameters used by climate modellers, the effects of a number of abiotic factors on the growth and survival of extant cryptogamic ground covers and their environmental impacts are reviewed. Factors include photosynthetically active radiation, ultraviolet radiation, temperature, water, oxygen, carbon dioxide, nitrogen, phosphorus, iron, surface roughness and albedo. A survey of the nature and extent of weathering facilitated by such vegetation concludes that it was limited based on depth of weathering when compared with that from rooted tracheophytes today, with minor effects on carbon dioxide drawdown. As global net productivity from Ordovician–Silurian CCs was very probably lower than today, and while the small fraction of intractable material in their organic carbon would have resulted in a more rapid turnover of terrestrial biomass, we conclude that there was decreased possibility of long‐term organic carbon burial. Hence, there would have been very limited increase in atmospheric oxygen and decrease in carbon dioxide resulting from carbon burial.

PalAss Go! URL: | Twitter: Share on Twitter | Facebook: Share on Facebook | Google+: Share on Google+