10.6084/m9.figshare.3454016.v1
Gregory J. Retallack
Gregory J.
Retallack
Silurian vegetation stature and density inferred from fossil soils and plants in Pennsylvania, USA
Geological Society of London
2016
cm
Silurian vegetation stature
Bloomsburg Formation show
Vascular land plants
palaeosol
land plants
USA
Drab haloed plant bases
Geology
2016-06-21 11:50:37
Journal contribution
https://geolsoc.figshare.com/articles/journal_contribution/Silurian_vegetation_stature_and_density_inferred_from_fossil_soils_and_plants_in_Pennsylvania_USA/3454016
<p>Silurian fossil plants range from small vascular plants (rhyniophytes) to moderately large fungi (nematophytes), but give
little idea of the stature, rooting depth and plant density of vegetation on land. Silurian to earliest Devonian palaeosols
from the Bloomsburg Formation show unusually deep bioturbation of several distinct kinds. Surface ground-parallel rhizomes
of vascular land plants (to 20 cm deep) are penetrated by burrows like those of millipedes (to 80 cm), but the deepest stratum
(down to 2 m below the surface) has features interpreted as bioturbation by fungal hyphae and rhizines. Plant-like axes associated
with palaeosols are evidence of vegetation with three distinct tiers above ground as inferred from diameters using allometric
scaling equations. Nematophytes (<em>Germanophyton psygmophylloides</em>), up to 1.3 m tall, formed a tier above herbaceous vascular land plants (30 cm) and ground cover (<2 cm tall) of thallose
organisms and litter. Drab haloed plant bases in the surface of palaeosols demonstrate that nematophytes grew densely (up
to 51 m<sup>−2</sup>) with spacing (20 cm) that closed canopy in seasonally dry wetland palaeosols, comparable with modern marsh vegetation. Vascular
land plants of well-drained soils in contrast were scattered, with bare earth between. Wetland ground cover was thus more
extensive than cover of well-drained soils, and precursor lichens facilitated early evolution of vascular land plants.
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