Fossil evidence of Apocynaceae from the late Paleocene of India and its biogeographic significance

During the Cretaceous–Paleogene transition, the early diversification of angiosperms has captivated researchers, particularly their geographic origins and ecological expansion. Fossil records provide crucial insights into the evolutionary paths of key plant lineages, including Lamiids, a core eudicot clade comprising about 15% of angiosperm species. Despite their significance, fossil evidence for Lamiids remains sparse but invaluable. Here, we report an Apocynaceae leaf fossil belonging to Gentianales order of the Lamiids clade from the late Paleocene of India. Our findings suggest Apocynaceae likely originated in East Gondwana during late Cretaceous–Paleocene, migrating to Africa and Eurasia during subsequent periods. Fossil evidence indicates biotic exchanges among Africa, Eurasia, Tibet, and India during the Paleocene–Eocene, highlighting regional connectivity. Paleoclimatic data indicate tropical to subtropical conditions in India during the late Paleocene, fostering early diversification of Apocynaceae in Gondwanaland.