Spore clots in Rhynie chert
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Aglaophyton sporangium detail
Mature spores as in Fig.1 are released from the sporangia as loose grains, as expected. So it is surprising that spores are not seldom seen in globular lumps (Figs.2-5).
Aglaophyton spores

Fig.1 (right): Detail of Aglaophyton sporangium: wall with so-called palisade cells (left), sporogenic tissue, spores. Width of the picture 1.7mm.

Fig.2 (left): Aglaophyton spores, separate and in a small globular clot.
Width of the picture 1.4mm.
All pictures of same scale.

Aglaophyton spore clot Aglaophyton spore clot
Fig.3 (far left): Aglaophyton spores in a globular clot.
Width of the picture 1.4mm.

Fig.4 (left): Aglaophyton spores in a globular clot, apparently partially chewed up.
Width of the picture 1.4mm.

Aglaophyton spore clot

Fig.5 (right): Aglaophyton spores in a globular clot, with mineral debris apparently glued to the surface.
(One circular spore contour is faintly seen above left.) Width of the picture 1.4mm.

The peculiar clots shown here, all from one sample, require an explanation. The statement in [1] that "evidence for deliberately targeted spore feeding in the Early Devonian is not conclusive" had been contradicted by own observations in 2005: There were spore eaters around when the early land plants became preserved in the Rhynie chert. This has suggested a phantastic idea: Possibly some creature collected the scattered spores and glued them into spheres for storage and later use as food. A few spores nibbled off the surface of the clot in Fig.4 seems to support this assumption. The mineral debris sticking to the clot in Fig.5 supports the idea of glueing.
Unrelated to the clot problem but worth mentioning are lots of tiny black dots in Fig.5, probably microbes stuck to a former silica gel surface.
Rh9/93 (0.55kg), found by
S. Weiss in 2011, cut into 10 parts, Part5: Fig.1.
Rh2/4, obtained from Shanks in 1998, cut into 4 parts, Part2 returned. Part1 (slab, given to J. Gardavsky): Figs.4,5; Part3 (slab, in the own collection): Figs.2,3.

H.-J. Weiss       2019

[1]  K.S. Habgood, H. Hass, H. Kerp: Evidence for an early terrestrial food web: coprolites from the Early Devonian Rhynie chert.
        Proc. Roy. Soc. Edinburgh, Earth Sci. 94 (2004), 371-389.
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