Anatomically preserved early Cretaceous lycophyte shoots; enriching the paleontological record of Lycopodiales and Selaginellales

Abstract

Anatomically preserved lycophytes of the Lycopodiales and Selaginellales have been discovered among a diverse assemblage of plants and fungi in carbonate marine concretions at the Apple Bay locality along the shore of Holbert Inlet near the northern end of Vancouver Island, British Columbia, Canada. Lycopodialean stems are plectostelic and actinostelic, branch dichotomously, and are similar to both Lycopodicaulis oellgaardii and Lycoxylon spp. The Selaginella specimens represent the first anatomically preserved Selaginellales with excellent internal cellular preservation in the fossil record, and are described as Selaginella quatsinoense Rothwell et Stockey sp. nov. Stems have three and five exarch, monarch stelar segments, each of which is surrounded by an aerenchymatous endodermis with trabeculae. The leaf base is indented on the adaxial surface, suggesting the position of a ligule. These fossils document that species with diagnostic internal anatomy of modern Lycopodiales and Selaginellales evolved no later than the Valanginian of the early Cretaceous.