Fossil evidence of Trachycarpeae (Arecaceae) from the K-Pg of India and its biogeographic implications

A well-preserved petrified palm stem from the Upper Maastrichtian (Upper Cretaceous) to Lower Danian (Lower Paleocene) rocks (c. 66–65 Ma) of the Deccan Intertrappean Beds of Madhya Pradesh, Central India, displays a close resemblance to stems of the extant unplaced genus iWashingtonia/i H.Wendl. of Trachycarpeae, the largest tribe within the palm subfamily Coryphoideae. It has a Corypha-type organization, with reniforma, cordata, sagittata-shaped fibrovascular bundles, 2 (3–4) metaxylem vessels with excluded vascular zone position, and the presence of tabular parenchyma. The permineralized stem is described as a new species, iPalmoxylon trachycarpeaeense/i Kumar et Khan sp. nov. This, and earlier reported fossil taxa from the same sedimentary deposit, represents the oldest reliable megafossil record of Trachycarpeae from India and is important from a biogeographic perspective. This fossil palm stem supports a Gondwanan origin of the Trachycarpeae and is important for tracing their migration pathways from India to other continents after the docking of the Indian subcontinent with Eurasia during the early Paleocene, supporting an “Out-of-India” dispersal hypothesis.