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GIANT IMPACT. "Megaphylls altered the evolutionary trajectory of terrestrial plant and animal life, the biogeo-chemical cycling of nutrients, water and carbon dioxide and the exchange of energy between the land surface and the atmosphere." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

FLAT BIG LEAVES. "The vast majority of the estimated 250 000 or so extant species of flowering plants, as well as most gymnosperms and (extinct) pteridosperms, utilize(d) a flat-bladed megaphyll with a network of veins to capture solar energy for photosynthetic carbon assimilation." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

TWO LINEAGES. "Plants evolved leaves on at least two independent occasions and the legacy of these historic evolutionary events is represented in extant floras by microphylls in lycophytes (clubmosses, spikemosses and quillworts) and megaphylls in euphyllophytes (ferns, gymnosperms and angiosperms)." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

REFLEXIVE CYCLE. "In the long term, plants brought about a gradual and continual alteration of the global environment that modified selection pressures on subsequent generations, effectively facilitating their own evolution through the process of niche construction." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

GLOBAL SUCCESS. "Evidently, leaves are a global success. However, the advent of large megaphylls took place some 40–50 million years (Myr) after the origination of vascular land plants, suggesting that they were far from an evolutionary inevitability." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

EXAPTATION OF GENES. "Whether megaphylls, which arose independently in four vascular plant lineages (ferns, sphenopsids, progymnosperms and seed plants), recruited the same gene systems is open to investigation. However, this does seem a possibility given that a common developmental mechanism for leaf production appears to have been recruited independently at least twice in the evolution of land plants." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

INCREASED RESPIRATORY CHANNELS. "The large fall in CO2 corresponded with a marked rise in the stomatal density of vascular land plants, with densities increasing a 100-fold from 5–10mm (-2) on early vascular plant axes to 800–1000 mm (-2) on the cuticles of late Carboniferous megaphylls." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

THE UP INNOVATION. "Deriving from the apical vegetative meristem flank, the abaxial surface is as old as land plants themselves, so genes specifying adaxial identity constitute a key innovation in leaf evolution. Plants appear to have evolved a complex hierarchy of transcription factor activation and depression, with the HD-ZIP (homeodomain–leucine zipper) gene family promoting adaxial leaf surfaces and others promoting abaxial differentiation." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

BIG LEAVES AND DROP IN CO2. "The mechanistic hypothesis of Beerling et al. (2001) links the gap between the earliest vascular plants and the advent of large megaphylls with a dramatic 90% drop in the atmospheric CO2 concentration during the late Palaeozoic." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

KNOWING UP FROM DOWN. "Leaf production also requires differentiation between adaxial (upper) and abaxial (lower) surfaces because the former is specialized for the efficient capture of solar energy and the latter for gas exchange." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn