scholarly journals History and contemporary significance of the Rhynie cherts—our earliest preserved terrestrial ecosystem

2017 ◽  
Vol 373 (1739) ◽  
pp. 20160489 ◽  
Author(s):  
Dianne Edwards ◽  
Paul Kenrick ◽  
Liam Dolan
Keyword(s):  
Terrestrial Ecosystem ◽  
Analytical Techniques ◽  
Land Plant ◽  
Life Cycles ◽  
Systems Science ◽  
Developmental Genetics ◽  
Earth Systems ◽  
Plant Life ◽  
Rhynie Chert ◽  
Tissue Systems

The Rhynie cherts Unit is a 407 million-year old geological site in Scotland that preserves the most ancient known land plant ecosystem, including associated animals, fungi, algae and bacteria. The quality of preservation is astonishing, and the initial description of several plants 100 years ago had a huge impact on botany. Subsequent discoveries provided unparalleled insights into early life on land. These include the earliest records of plant life cycles and fungal symbioses, the nature of soil microorganisms and the diversity of arthropods. Today the Rhynie chert (here including the Rhynie and Windyfield cherts) takes on new relevance, especially in relation to advances in the fields of developmental genetics and Earth systems science. New methods and analytical techniques also contribute to a better understanding of the environment and its organisms. Key discoveries are reviewed, focusing on the geology of the site, the organisms and the palaeoenvironments. The plants and their symbionts are of particular relevance to understanding the early evolution of the plant life cycle and the origins of fundamental organs and tissue systems. The Rhynie chert provides remarkable insights into the structure and interactions of early terrestrial communities, and it has a significant role to play in developing our understanding of their broader impact on Earth systems. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

scholarly journals Changing expressions: a hypothesis for the origin of the vascular plant life cycle

2017 ◽  
Vol 373 (1739) ◽  
pp. 20170149 ◽  
Author(s):  
Paul Kenrick
Keyword(s):  
Life Cycle ◽  
Vascular Plants ◽  
Vascular Plant ◽  
Terrestrial Ecosystem ◽  
Life Cycles ◽  
Developmental Genetics ◽  
Vascular Tissues ◽  
Plant Life ◽  
Combining Data ◽  
Critical Components

Plant life cycles underwent fundamental changes during the initial colonization of the land in the Early Palaeozoic, shaping the direction of evolution. Fossils reveal unanticipated diversity, including new variants of meiotic cell division and leafless gametophytes with mycorrhizal-like symbioses, rhizoids, vascular tissues and stomata. Exceptional fossils from the 407-Ma Rhynie chert (Scotland) play a key role in unlocking this diversity. These fossils are reviewed against progress in our understanding of the plant tree of life and recent advances in developmental genetics. Combining data from different sources sheds light on a switch in life cycle that gave rise to the vascular plants. One crucial step was the establishment of a free-living sporophyte from one that was an obligate matrotroph borne on the gametophyte. It is proposed that this difficult evolutionary transition was achieved through expansion of gene expression primarily from the gametophyte to the sporophyte, establishing a now extinct life cycle variant that was more isomorphic than heteromorphic. These changes also linked for the first time in one developmental system rhizoids, vascular tissues and stomata, putting in place the critical components that regulate transpiration and forming a physiological platform of primary importance to the diversification of vascular plants. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

scholarly journals Fungi and fungal interactions in the Rhynie chert: a review of the evidence, with the description of Perexiflasca tayloriana gen. et sp. nov. †

2017 ◽  
Vol 373 (1739) ◽  
pp. 20160500 ◽  
Author(s):  
Michael Krings ◽  
Carla J. Harper ◽  
Edith L. Taylor
Keyword(s):  
Three Dimensional ◽  
Terrestrial Ecosystem ◽  
Land Plant ◽  
Biological Degradation ◽  
Microbial Life ◽  
Plant Parts ◽  
Comprehensive Information ◽  
Rhynie Chert ◽  
Fungal Associations ◽  
Fungal Interactions

The Lower Devonian Rhynie chert is one of the most important rock deposits yielding comprehensive information on early continental plant, animal and microbial life. Fungi are especially abundant among the microbial remains, and include representatives of all major fungal lineages except Basidiomycota. This paper surveys the evidence assembled to date of fungal hyphae, mycelial cords and reproductive units (e.g. spores, sporangia, sporocarps), and presents examples of fungal associations and interactions with land plants, other fungi, algae, cyanobacteria and animals from the Rhynie chert. Moreover, a small, chytrid-like organism that occurs singly, in chain-like, linear arrangements, planar assemblages and three-dimensional aggregates of less than 10 to individuals in degrading land plant tissue in the Rhynie chert is formally described, and the name Perexiflasca tayloriana proposed for the organism. Perexiflasca tayloriana probably colonized senescent or atrophied plant parts and participated in the process of biological degradation. The fungal fossils described to date from the Rhynie chert constitute the largest body of structurally preserved evidence of fungi and fungal interactions from any rock deposit, and strongly suggest that fungi played important roles in the functioning of the Early Devonian Rhynie ecosystem. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

How land plant life cycles first evolved

Science ◽  
2017 ◽  
Vol 358 (6370) ◽  
pp. 1538-1539 ◽  
Author(s):  
Paul Kenrick
Keyword(s):  
Land Plant ◽  
Life Cycles ◽  
Plant Life

scholarly journals Bilaterally symmetric axes with rhizoids composed the rooting structure of the common ancestor of vascular plants

2017 ◽  
Vol 373 (1739) ◽  
pp. 20170042 ◽  
Author(s):  
Alexander J. Hetherington ◽  
Liam Dolan
Keyword(s):  
Vascular Plants ◽  
Common Ancestor ◽  
Terrestrial Ecosystem ◽  
Bilateral Symmetry ◽  
Land Plant ◽  
Land Plants ◽  
Free Living ◽  
Rhynie Chert ◽  
The Common ◽  
Almost All

There are two general types of rooting systems in extant land plants: gametophyte rhizoids and sporophyte root axes. These structures carry out the rooting function in the free-living stage of almost all land plant gametophytes and sporophytes, respectively. Extant vascular plants develop a dominant, free-living sporophyte on which roots form, with the exception of a small number of taxa that have secondarily lost roots. However, fossil evidence indicates that early vascular plants did not develop sporophyte roots. We propose that the common ancestor of vascular plants developed a unique rooting system—rhizoidal sporophyte axes. Here we present a synthesis and reinterpretation of the rootless sporophytes of Horneophyton lignieri , Aglaophyton majus , Rhynia gwynne-vaughanii and Nothia aphylla preserved in the Rhynie chert. We show that the sporophyte rooting structures of all four plants comprised regions of plagiotropic (horizontal) axes that developed unicellular rhizoids on their underside. These regions of axes with rhizoids developed bilateral symmetry making them distinct from the other regions which were radially symmetrical. We hypothesize that rhizoidal sporophyte axes constituted the rooting structures in the common ancestor of vascular plants because the phylogenetic positions of these plants span the origin of the vascular lineage. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

Reproduction in Plant Life Cycles

Biology ◽  
1998 ◽  
pp. 235-253
Author(s):  
Julian Sutton
Keyword(s):  
Life Cycles ◽  
Plant Life

SCIENCE AND GOVERNMENT: An Earth Systems Science Agency

Science ◽  
2008 ◽  
Vol 321 (5885) ◽  
pp. 44-45 ◽  
Author(s):  
M. Schaefer ◽  
D. J. Baker ◽  
J. H. Gibbons ◽  
C. G. Groat ◽  
D. Kennedy ◽  
...  
Keyword(s):  
Systems Science ◽  
Earth Systems ◽  
Science And Government
Sign in / Sign up

Export Citation Format

Share Document