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Permanent link (DOI): https://doi.org/10.7939/R3DR2PK8P

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Todea from the Lower Cretaceous of western North America: implications for the phylogeny, systematics, and evolution of modern Osmundaceae Open Access

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Author or creator
Jud, N.A.
Rothwell, G.W.
Stockey, R.A.
Additional contributors
Subject/Keyword
Osmundastrum
Cretaceous
fern phylogeny
rhizome
Todea
Osmundaceae
Type of item
Journal Article (Published)
Language
English
Place
Time
Description
The first fossil evidence for the fern genus Todea has been recovered from the Lower Cretaceous of British Columbia, Canada, providing paleontological data to strengthen hypotheses regarding patterns of evolution and phylogeny within Osmundaceae. The fossil consists of a branching rhizome, adventitious roots, and leaf bases. The dictyoxylic stem has up to eight xylem bundles around a sclerenchymatous pith. Leaf traces diverge from cauline bundles in a typical osmundaceous pattern and leaf bases display a sheath of sclerenchyma around a C-shaped xylem trace with 2 – 8 protoxylem strands. Within the adaxial concavity of each leaf trace, a single sclerenchyma bundle becomes C-shaped as it enters the cortex. The sclerotic cortex is heterogeneous with an indistinct outer margin. The discovery of Todea tidwellii sp. nov. reveals that the genus Todea evolved by the Lower Cretaceous. A phylogenetic analysis combining morphological characters of living and extinct species with a previously published nucleotide sequence matrix confirms the taxonomic placement of T. tidwellii . Results also support the hypothesis that Osmunda s.l. represents a paraphyletic assemblage and that living species be segregated into two genera, Osmunda and Osmundastrum . Fossil evidence confirms that Osmundaceae originated in the Southern Hemisphere during the Permian, underwent rapid diversification, and species extended around the world during the Triassic. Crown group Osmundaceae originated by the Late Triassic, with living species appearing by the Late Cretaceous.
Date created
2008
DOI
doi:10.7939/R3DR2PK8P
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This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
Citation for previous publication
Jud, N. A., Rothwell, G. W., & Stockey, R. A. (2008). Todea from the Lower Cretaceous of western North America: implications for the phylogeny, systematics, and evolution of modern Osmundaceae. American Journal of Botany, 95(3), 330-339. DOI: 10.3732/ajb.95.3.330
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