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. 2021 Sep 3;44(4):406-416.
doi: 10.1016/j.pld.2021.08.003. eCollection 2022 Jul.

Leaf fossils of Sabalites (Arecaceae) from the Oligocene of northern Vietnam and their paleoclimatic implications

Ai Song  1   2 , Jia Liu  2 , Shui-Qing Liang  2 , Truong Van Do  3   4 , Hung Ba Nguyen  3 , Wei-Yu-Dong Deng  2 , Lin-Bo Jia  5 , Cédric Del Rio  2 , Gaurav Srivastava  6 , Zhuo Feng  1 , Zhe-Kun Zhou  2 , Jian Huang  2 , Tao Su  2
Affiliations

Leaf fossils of Sabalites (Arecaceae) from the Oligocene of northern Vietnam and their paleoclimatic implications

Ai Song et al. Plant Divers. .

Abstract

Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia. Palms (Arecaceae) are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing. In this study, we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin, northern Vietnam. Characters of the fossil leaves, such as a fan-shaped costapalmate lamina, an unarmed petiole, a costa slightly enlarged at the base that then tapers distally into the blade, and well-preserved amphistomatic leaves with cuticles, suggest that they represent a new fossil species, which we herein designate Sabalites colaniae A. Song, T. Su, T. V. Do et Z.K. Zhou sp. nov. Together with other paleontological and palaeoclimatic evidence, we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.

Keywords: Fossil; Leaf; Oligocene; Paleoclimate; Palm; Vietnam.

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Conflict of interest statement

We have no competing interest.

Figures

Fig. 1
Fig. 1
Geological map with the location of the fossil site (modified from Petersen et al., 2005; Tha et al., 2017). a, Location of the study area. b, Picture in the field showing the palm-bearing layer; c, Location of the fossil site and geological map of the Hoanh Bo Basin showing the distribution of Dong Ho Formation and Tieu Giao Formation.
Fig. 2
Fig. 2
Sedimentological profile and fossil assemblage of the Dong Ho Formation and Tieu Giao Formation in the Hoanh Bo Basin.
Fig. 3
Fig. 3
Leaf blade of Sabalites colaniae. a, b, Gross morphology of the cospalmate blade (XTBG-VNMN-1-10395a/b); c, Leaf blade with a long, unarmed petiole (XTBG-VNMN-1-10396); d, Enlargement of the basal part of leaf blade: costa; e, Segments of the palm fossil. c, coast; up, unarmed petiole. Scale bar = 100 mm (a, b, c), 50 mm (d), 20 mm (e).
Fig. 4
Fig. 4
Comparison of leaf morphology and cuticular micromorphology of Sabalites colaniae (a–e) and living species Trachycarpus fortunei (f–j). a, f, leaf morphology showing the cospalmate blade, single-fold segments; b, c, g, h, amphistomatic cuticles showing the ordinary epidermal cells and stomatal bands; d, e, i, j, enlargement of the stomatal complex by light microscope and SEM.
figs1
figs1
See this image and copyright information in PMC

References

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