Another filamentous alga in the Rhynie
The alga filaments described
here have been seen on a cut face of only one chert sample on an area
of about 1mm2, as
essentially covered by Fig.1. They
seem to be liable to fragmentation, possibly due to partial decay.
Apparently the decay had affected the cells differentially: Most of
them seem to are more or less shrunken but some seem to are not
(Fig.2). Even one of the best-preserved cells (Fig.2) does not reveal
what has happened to its content prior to and during silicification,
and what to think of its fossil content.
to their rare presence in the Rhynie chert, filamentous algae (other
charophytes or cyanobacteria) seem to have been investigated only once
 and never since. The
cell sizes of this alga differ significantly from those of either
species described in . Considering that the narrower cells in Fig.1
may have shrunken, the original width and length seem to be about 20Ám
and up to 50Ám.
For comparison, cells are much wider, 28-40Ám, and shorter, 23-41Ám,
rotundata . They are narrower, 8-16.5Ám, and shorter,
16-40Ám, for Rhynchertia punctata
. Hence, this alga may be regarded as a not yet described species
Fig.1: Randomly arranged filamentous alga fragments in
chert. Image width 1.3mm.
Fig.2 (below): Detail of Fig.1 (right of the
middle), cells in various states of decay. Image width 0.2mm. Photograph: G. Schmahl.
the collection of Steffen
collected decades ago by
formerly owned by A.G.
Rhynie, documented here under the label Rh2/301.2 .
David S. Edwards, A.G.
Lyon: Algae from the
Rhynie Chert. Bot. J. Linnean Society 86(1983),