Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and Chengdu University of Technology recently discovered many late Paleocene palm leaf fossils from Lazi County, southern Tibetan Plateau. This discovery provides new and compelling evidence that the Kohistan-Ladakh Island Arc (KLIA) served as a key series of steppingstones for the dispersal of palms from the India Plate to southern Tibet.

Related results were published in Review of Palaeobotany and Palynology.

The palm fossils discovered in Lazi County, southern Tibet, exhibit morphological difference from any previously reported palm fossil species. Based on morphological comparison with other fossil palm leaf records, the researchers amended the palm fossils as Sabalites striatipetiolaphyllum.

These fossil leaves, characterized by induplicate fan-shaped costapalmate laminae with unarmed petioles, suggest an affiliation with the subfamily Coryphoideae. Even though the shape of the lamina is largely consistent with Livistona tibetica, the petioles of extant Livistona species are typically armed whereas the petiole of new discovered fossils is unarmed.

Combining the new palm fossils with the previous palm fossil records, the researchers proposed that the KLIA is the most plausible dispersal route between the Indian Plate and southern Tibetan region. The discovery of palm fossils on southern Tibetan Plateau suggested that, at least before the late Paleocene, palms had spread from India to the southern Tibetan region via the KLIA.

Therefore, the Kohistan-Ladakh Island Arc acted as an important stepping stone for palm dispersal between India and southern Tibet during the Late Paleocene. Palm plants dispersed to central Tibet during the late Eocene.

“Our newly discovered palm fossil record provides important evidence for floristic exchange between India and Asia, as well as a warm climate in southern Tibet at that time,” said LI Shufeng of XTBG.

Published: 3 December 2024