Intra-stomachal Magnoliales phytoliths provide definitive evidence for folivory in basal avialans of the Early Cretaceous Jehol Biota

Abstract

Abstract Angiosperms became the dominant plant group in early to middle Cretaceous terrestrial ecosystems, coincident with the timing of the earliest pulse of bird diversification. While birds and angiosperms exhibit strong interactions across pollination/nectivory, seed dispersal/frugivory, and folivory, documentation of the evolutionary origins and construction of that ecological complexity remains scarce in the Mesozoic. Through the first study of preserved in situ dietary derived phytoliths in a nearly complete skeleton of the early diverging avialan clade Jeholornithidae, we provide direct dietary evidence of Jeholornis consuming angiosperm leaves of the clade Magnoliales, and these results lend further support for early ecological connections among the earliest birds and angiosperms. The broad diet of the early diverging avialan Jeholornisincluding fruits, seeds, and leaves marks a clear transition in the early evolution of birds in the establishment of an arboreal (angiosperm) herbivore niche in the early Cretaceous occupied largely by birds today. Morphometric reanalysis of the lower jaw of Jeholornis additionally supports a generalized morphology similar to the living folivore the hoatzin.