Araucarioid wood from the late Oligocene–early Miocene of Hainan Island: first fossil evidence for the genus Agathis in the Northern Hemisphere
Although many fossil and molecular data suggest migrations from Malesia and Asia to Australia appear to dominate floristic exchange between Australian and Asian rainforests, evidence is emerging that demonstrate dispersal of plant groups from Australia to Asia. In this paper, a new species Agathis l...
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Veröffentlicht in: | Journal of plant research 2020-03, Vol.133 (2), p.157-173 |
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Sprache: | eng |
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Zusammenfassung: | Although many fossil and molecular data suggest migrations from Malesia and Asia to Australia appear to dominate floristic exchange between Australian and Asian rainforests, evidence is emerging that demonstrate dispersal of plant groups from Australia to Asia. In this paper, a new species
Agathis ledongensis
sp. nov. is described on the basis of silicified wood from the late Oligocene–early Miocene of the Qiutangling Formation in Ledong, Hainan Island, South China. It is the first fossil record of
Agathis
in the Northern Hemisphere, and the only known fossil evidence of its dispersal outside of Gondwana. The close affinity of the fossil wood from Ledong with the genus
Agathis
was confirmed by comparing quantitative traits in 31 wood samples of 20 species representing all three extant genera of the Araucariaceae. The percentage of tracheids with uniseriate pitting on radial walls is shown as an additional diagnostic trait for separating
Agathis
and
Wollemia
from
Araucaria
. The wood of
Agathis ledongensis
provides evidence for the dispersal of this important plant group from Australia, or another Gondwanan terrane, to eastern Asia based on reliable fossil data. It records the occurrence of this genus in Hainan Island by the early Miocene, i.e. at the beginning of the formation of the island chains between Australia and the South-East Asia and thus the provision of a land migration route. As the land routes between these continents were restricted at that time, the migration of
Agathis
to Malesia and Asia was presumably facilitated by long-distance dispersal of its winged seeds by wind. |
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ISSN: | 0918-9440 1618-0860 |
DOI: | 10.1007/s10265-019-01165-z |