Ultrastructure of Cambrian cryptospores and the early evolution of the plant spore wall

Pages	90–106
DOI	10.37520/fi.2024.009
Keywords	Rome Formation, origin of land plants, sporopollenin, charophytes, terrestrialization, paleopalynology, sporoderm, Conasauga Group, synoecosporal wall
Type of Article	Peer-reviewed
Citation	TAYLOR, Wilson A. a STROTHER, Paul K.. Ultrastructure of Cambrian cryptospores and the early evolution of the plant spore wall. Fossil Imprint / Acta Musei Nationalis Pragae, Series B – Historia Naturalis. Prague: National Museum, 2024, 80(1), 90–106. DOI: https://doi.org/10.37520/fi.2024.009. ISSN 2533-4050 (tisk), 2533-4069 (online). Also available from: https://www.nm.cz/en/periodicals/fossil-imprint-acta-musei-nationalis-pragae-series-b-historia-naturalis/80-1/ultrastructure-of-cambrian-cryptospores-and-the-early-evolution-of-the-plant-spore-wall

Fossil Imprint / Acta Musei Nationalis Pragae, Series B – Historia Naturalis | 2024/80/1

Terrestrially-derived cryptospores from Cambrian deposits in eastern Tennessee were examined using transmission electron microscopy (TEM) to determine the underlying structural basis for spore wall construction in these pre-embryophytic spore types. In addition to previously-described species from the middle Cambrian Conasauga Group, we examined new specimens extracted from the Rome Formation, which are coeval to the oldest reported cryptospores from North China. Our results reveal a substantial diversity of endogenous laminated sporoderm construction, expanding on the three basic types described previously. The underlying cellular processes involved in the production of sporopollenin wall construction were in place by the middle Cambrian, but a modern form of spore wall assembly did not evolve until the canalization of plant-like sporogenesis during the Middle Ordovician.

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