The Base of the Foodchain Moves onto Land - The Results of
Terrestrialization
- Requirements for Land Dwelling
- Prevent dessication
- Algal resting stages are resistant
- Maintain gas exchange
- Cuticle prevents gas exchange,holes needed in cuticle of early land plants
- Stabilization on land and osmotic balance
- Internal water relations
- Conducting Cells for water and photosynthate
- Green Plant Ancestors?
- Had similar physiological characteristics to those successful colonizers
- Include photosynthetic pigment type (chlorophyll )
- Photosynthetic storage product
- Cellulose in the cell walls
- Algal group with these features is the Green Algae (Chlorophyta).
- First Evidence of Land Plants
- First evidence may be from the Ordovician
- Unequivocal in E. Silurian
- FWPassage Creek
- Banded and smooth tubular elements
- Cuticular and membranaceous fragments
- Alete and trilete spores and spore tetrads
- Small septate hyphal filaments and mats of fungi
- Plants Unknown Today?
- No evidence in Early Silurian for true vascular (xylem & phloem conducting tissues)
plants
- Silurian-Devonian Landscapes
- Rhyniophytes
- Seed-less, spore bearing with a very low stature
- Adaptive radiation in the Early Devonian (Extinct)
- Extinct Zosterophylls (Extinct) & Trimerophytes (Extinct) and extant Lycopsids ("club
mosses")
- Late Devonian Pteridophytes ("ferns") and Sphenopsids ("horse-tails")
- First Forests
- Spore-producing plants are first trees with wood
- Seed habit occurred in the Late Devonian resulting in another radiative burst
- First true gymnosperms in Late Devonian and diversify in the Carboniferous
- Conifers first appear in the Carboniferous.
- Permo-Carboniferous
- Coal swamps very different from today
- Wide diversity of coexisting plant groups
- Lycopsids, sphenopsids, ferns, and gymnosperms all occupy similar ecological
space
- Icehouse conditions provide climate for diverse ecologies.
- Transition to the Greenhouse
- Climatic changes in the Late Pennsylvanian result in the demise and extinction of the
major peat-forest forms (except in China)
- Modernization of Global Vegetation
- Lineages survive, but dominant plants are extinct
- Permian aridity forces a biotic change on land to seed plant domination
- Gymnosperms come to dominate the Mesophytic beginning in the mid-Permian
- A Landscape without Flowers
- Gymnosperms include:
- Cycads (extant)
- Cycadophytes (extinct)
- Pteridosperms (extinct)
- Conifers
- Taxodiaceae
- Araucariaceae