Abstract
Strap-shaped, parallel-veined leaves of Podozamites and Pseudotorellia are among the most common fossils in Late Triassic to Early Cretaceous floras from the Northern Hemisphere. Podozamites is considered to be the leaf of a voltzian conifer, but its cuticle is poorly known, whereas Pseudotorellia, with a thick cuticle and haplocheilic stomata, is commonly considered to be the leaf of a ginkgoalean. Here we describe the leaf morphology, cuticle and stomata of Podozamites and Pseudotorellia based on excellently preserved material from the Early Cretaceous of central Mongolia. Podozamites harrisii sp. nov. has transversely oriented, paracytic (probably syndetocheilic) stomata that are regularly arranged in longitudinal files. Pseudotorellia resinosa sp. nov. and Pseudotorellia palustris sp. nov. have scattered, longitudinally oriented stomata in which the two guard cells are sunken and surrounded by 2–5 specialized lateral subsidiary cells and 1–3 unspecialized polar cells. Association evidence and similarities in cuticular structure suggest that Podozamites harrisii was produced by the same plant as the seed cone Krassilovia. The distinctive stomatal pattern of Podozamites harrisii and Krassilovia is also seen in some species of Swedenborgia and Cycadocarpidium, suggesting these plants may all belong to the same natural group. Cycadocarpidium, Krassilovia and Swedenborgia have previously been treated as conifers, but their transversely oriented, paracytic stomata hint instead at a possible relationship with Bennettitales and Gnetales.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 111-137 |
| Number of pages | 27 |
| Journal | Journal of Systematic Palaeontology |
| Volume | 16 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jan 26 2018 |
Funding
We thank T. Gombosuren and O. Nyamsambuu for assistance with fieldwork in Mongolia, D. E. G. Briggs and S. Butts for use of facilities in the Yale University invertebrate palaeontology laboratory, I. Glasspool and S. Grant for curatorial assistance, and C. Thornton, L. Nowack, A. Basey, B. Cooper, D. Bruzzese and S. Crane for help sorting the fossil material. We are also grateful to E. V. Bugdaeva and N. V. Nosova for supplying key references, and Z. Zhou and M. Pole for constructive discussions. Funding for this work was provided by NSF grant DEB-1348456 to PSH and PRC, Grants-in-Aid for Scientific Research (21405010 and 24405015) from the Japan Society for the Promotion of Science to MT, and National Natural Science Foundation of China grant 41206173 and Youth Innovation Promotion Association, CAS (2017359) to GS. Division of Environmental Biology, Japan Society for the Promotion of Science, National Natural Science Foundation of China, Youth Innovation Promotion Association of the Chinese Academy of Sciences We thank T. Gombosuren and O. Nyamsambuu for assistance with fieldwork in Mongolia, D. E. G. Briggs and S. Butts for use of facilities in the Yale University invertebrate palaeontology laboratory, I. Glasspool and S. Grant for curatorial assistance, and C. Thornton, L. Nowack, A. Basey, B. Cooper, D. Bruzzese and S. Crane for help sorting the fossil material. We are also grateful to E. V. Bugdaeva and N. V. Nosova for supplying key references, and Z. Zhou and M. Pole for constructive discussions. Funding for this work was provided by NSF grant DEB-1348456 to PSH and PRC, Grants-in-Aid for Scientific Research (21405010 and 24405015) from the Japan Society for the Promotion of Science to MT, and National Natural Science Foundation of China grant 41206173 and Youth Innovation Promotion Association, CAS (2017359) to GS.
Keywords
- Early Cretaceous
- Ginkgo
- Podozamites
- Pseudotorellia
- paracytic stoma
- voltzian
ASJC Scopus subject areas
- Palaeontology