A structurally preserved magnolialean fructification from the mid-Cretaceous of Japan

Abstract

Fossil evidence throwing light on the origin and diversification of angiosperms (flowering plants) has been increasing rapidly over the past 10 years. Most palaeobotanists accept that angiosperms first diversified in the Barremian stage of the Cretaceous, but this is based mainly on stratophenetic morphological studies of palynomorphs and vegetative organs1–3. Reproductive organs such as flowers and fructifications, which are vital to a full understanding of angiosperm evolution, are rare and have only recently been described in any detail from Cretaceous rocks4–11, and even these are generally preserved as compressions or as fusinized remains. Here I report a permineralized angiosperm floral axis bearing conduplicate carpels from mid-Cretaceous sediments of Hokkaido, Japan. Its structure most closely resembles that of extant Monimiaceae and Austrobaileyaceae of the Magnoliales, particularly in the concave receptacle, but it shows several features considered more primitive than those occurring in any extant family. The fossil extends and clarifies knowledge of the structure and evolution of early angiosperms and is the first report of a permineralized angiosperm fructification of Cretaceous age.