Eocene palms from central Myanmar in a South-East Asian and global perspective: evidence from the palynological record

Autor(en)

Huasheng Huang, Robert Morley, Alexis Licht, Guillaume Dupont-Nivet, Fridgeir Grimsson, Reinhard Zetter, Jan Westerweel, Zaw Win, Day Wa Aung, Carina Hoorn

Abstrakt

In the Palaeogene, pollen assemblages at low and mid latitudes are characterized by abundant palm and palm-like (PPL) taxa. Although these taxa have been widely reported, their occurrence in the Palaeogene of Myanmar remains poorly documented. Here we report on the morphology of PPL pollen along a middle to upper Eocene sedimentary sequence in central Myanmar and discuss their nearest living relatives (NLRs). Principal components analysis (PCA) indicates that Palmaepollenites kutchensis, Dicolpopollis and Longapertites were dispersed from freshwater plants, whereas the parent taxon of Proxapertites operculatus was probably a member of the coastal vegetation in the manner of Spinizonocolpites. This, with sedimentological data, suggests a palaeoenvironmental change from a brackish, tidally influenced environment to a fully freshwater setting through the late Eocene. Additionally, we mapped and compared the geographical distribution of selected Eocene palm taxa and their NLRs, and found that their distributions shrank after the Eocene. Moreover, in the Palaeogene, species diversity of selected PPL taxa seems lower in Myanmar than in the Indian subcontinent and other regions in South-East Asia. We hypothesize that in the Eocene the Indo–Asian collision zone formed a ‘hotspot’ for palm diversity, which is reflected in species-rich palynofloras. However, the local palm diversity declined after the Eocene, whereas, at the global level, palm distribution was distinctly reduced between the Eocene and the present. We propose that the retreat of the palms may have occurred as early as the Eocene – Oligocene Transition (EOT), but this remains to be confirmed by the study of EOT pollen records in tropical regions.

Organisation(en)

Department für Botanik und Biodiversitätsforschung, Institut für Paläontologie

Externe Organisation(en)

University of Amsterdam (UvA), Palynova Limited, University of Washington, Universität Potsdam, Shwe Bo University, Yangon University, Université Rennes-II

Journal

Botanical Journal of the Linnean Society

Band

194

Seiten

177-206

Anzahl der Seiten

30

ISSN

0024-4074

DOI

https://doi.org/10.1093/botlinnean/boaa038

Publikationsdatum

07-2020

Peer-reviewed

Ja

ÖFOS 2012

106008 Botanik, 105117 Paläobotanik

Schlagwörter

ASJC Scopus Sachgebiete

Plant Science, Palaeontology, Ecology, Evolution, Behavior and Systematics

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/eocene-palms-from-central-myanmar-in-a-southeast-asian-and-global-perspective-evidence-from-the-palynological-record(b762e16d-204e-4e75-9da6-648509a4cfab).html