Cotton's Ancient Genesis: Amber Fossils from 99 Million-Year-Old Mid-Cretaceous Redefine Evolutionary Roadmap in Malvaceae

Cottons(Figure 6 ) , characteristic of their Fibrous seeds, are a crop of great economic importance ¹ . Various molecular estimates have provided different predictions on the origin time of Malvaceae ² , which includes cotton ( Gossypium ). However, most of these predictions, which are based on molecular data, are tentative and badly need to be tested on the basis of fossil evidence. As a unique fossil Lagerstatt, Myanmar amber has yielded abundant and various fossils (including flowers), thus opening a unique window into angiosperm evolution. To date, no Cretaceous fossils have shed any light on the evolution of cotton. Here we report more than one thousand fibrous seeds of four types embedded in a single piece of Myanmar amber. The occurrence of these fibrous seeds indicates that cottons, which shaped the first industrial revolution, have a history traced back to the Mid-Cretaceous (99 Ma ago). Our outcome pushes the age of Malvaceae back into more ancient ages.