Stomata in Cretaceous fossils


Fig. 3. Ginkgo sp. A, TLM view of two stomatal complexes (SL5572, scale 1⁄4 50 mm); B, TLM view of single stomatal complex with at least four papillae (SL5572, scale 1⁄4 20 mm); C, SEM view of the inner cuticular surface showing one stomatal complex (S-1755, scale 1⁄4 10 mm); D, SEM view of the outer cuticular surface showing one stomatal complex with six papillae (S-1755, scale 1⁄4 10 mm).

Cretaceous plant fossils of Pitt Island, the Chatham group, New Zealand

by Pole M., Philippe M. (2010)

Mike Pole, Marc Philippe,

In Alcheringa: An Australasian Journal of Palaeontology, 34: 3, 231 — 263 – DOI: 10.1080/03115511003659085 –

2010-pittisland.pdf


Fig. 4. Araucariaceae: Araucaria rangiauriaensis sp. nov.; A, SEM view of a single leaf (S-1727, scale 1⁄4 1 mm); B, TLM view of stomatal zone (SL5575, scale 1⁄4 50 mm); C, SEM view of outer surface of a stomatal zone showing obliquely oriented stomata (S-1727, scale 1⁄4 20 mm); D, SEM view of the inner cuticular surface of a stomatal zone (SL5575, scale 1⁄4 20 mm); E, TLM view of typical epidermal cells (SL5575, scale 1⁄4 20 mm); F, TLM view of a single stomatal complex (SL5575, scale 1⁄4 40 mm).

Abstract

Pitt Island, a part of the Chathams Islands group, lies 700 km east of New Zealand. Its geology includes the Tupuangi Formation, dated as Motuan to Teratan (late Albian to Santonian) on the basis of palynology. Samples of Tupuangi Formation mudstone yielded leaf cuticle assemblages dominated by araucarian and podocarp conifers and locally by angiosperms.

The 12 distinguishable conifer taxa include a new species of Araucaria, A. rangiauriaensis, and the extinct genera Eromangia, Kakahuia (both Podocarpaceae), Otwayia (Cheirolepidiaceae), Paahake (Taxodiaceae or Taxaceae) and possibly Katikia (Podocarpaceae).

Ginkgo and two types of dicotyledonous angiosperm cuticle are present. Based on the absence of bennettitaleans and rarity of Ginkgo, a Turonian or slightly younger age is inferred, making the Pitt Island assemblage the first Turonian plant macrofossils documented from New Zealand.


Fig. 9. Podocarpaceae: Kakahuia sp. A, TLM view showing scattered stomata and prominent papillae (SL5566, scale 1⁄4 50 mm); B, TLM view of a single stomata surrounded by papillae (SL5566, scale 1⁄4 20 mm); C, SEM view of outer surface showing stomata with stomatal pores very subdued (S-1749, scale 1⁄4 20 mm); D, SEM view of inner surface with many stomata (S-1749, scale 1⁄4 20 mm); E, F, TLM views of typical epidermal cells on non-stomatal surface (SL5566, scale 1⁄4 20 mm).

The fossils provide a window into southern high-latitude (polar) vegetation of the mid-Cretaceous. Conifer charcoal (probably of Podocarpaceae) is locally abundant and suggests that fire was an important part of the ecosystem. A broad analogy with modern boreal conifer-deciduous angiosperm forests is suggested although clearly with warmer temperatures


Fig. 11. Podocarpaceae sp. ‘chained’. A, TLM view of stomatal rows. Note darker staining (thicker) subsidiary cell cuticle (SL5642, scale 1⁄4 50 mm); B, TLM view of single stomatal complex showing strong rim. (SL5643, scale 1⁄4 20 mm); C, TLM view of stomatal rows (SL5643, scale 1⁄4 50 mm); D, TLM view (SL5711, scale 1⁄4 50 mm); E, SEM view of outer surface showing stomatal rows with prominent ring of raised subsidiary cells (S-1757, scale 1⁄4 20 mm); F, SEM view of inner surface of a stomatal complex (S-1757, scale 1⁄4 10 mm).

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Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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