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| Calophyllum suraikholaensis Awasthi & Prasad, 1990 in Thongsangtum, Huang, Li, Thasod et Su, 2023. |
Abstract
Fossils from tropical Asia, which are far from fully investigated, are important for understanding the evolution of plant diversity and the associated surrounding environment there. In this study, we report, as the first record in Thailand, the well-preserved leaf fossils of Calophyllum Linnaeus (Calophyllaceae) from the upper Oligocene–Lower Miocene lacustrine deposits in Li Basin, northern Thailand. The fossils were identified through detailed comparison with leaves of extant and fossil species. These leaf fossils are assigned to Calophyllum based on several key leaf characteristics such as oblanceolate or oblong in shape and parallel secondary veins, nearly perpendicular to the midvein, as well as secondary veins alternate, closely placed, craspedodromous, parallel, dense, and distinct on surface, forming marginal veins. Based on detailed morphological comparison, these fossil leaves are assigned to C. suraikholaensis Awasthi and Prasad, 1990 and Calophyllum sp. The discovery of Calophyllum indicates a montane subtropical to tropical climate in northern Thailand during the Oligocene–Miocene. Together with previous fossil records, these results suggest that this genus probably originated in India during the Paleogene, and spread from India to Indochina during the Neogene, leading to its modern distribution, which currently prefers tropical climates.
Keywords: Calophyllum, Miocene, Li Basin, Thailand, palaeoecology, leaf fossil
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| Fossil leaves of Calophyllum suraikholaensis. XTBG |
Napussawan Thongsangtum, Jian Huang, Shu-Feng Li, Yupa Thasod and Tao Su. 2023. Calophyllum (Calophyllaceae) from late Oligocene–Early Miocene of Li Basin, northern Thailand and its biogeographic and paleoclimatic implications. Palaeoworld. In Press. DOI: 10.1016/j.palwor.2023.09.002
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