Modeling compositional heterogeneity resolves deep phylogeny of flowering plants

Yuzhoua juvenilis: Another Angiosperm Seen in the Early Permian?

"How old are angiosperms" is a frequently asked but still unanswered question. Although the underlying reason includes a lack of consensus on the criterion for fossil angiosperms, limited fossil finds, and other factors, the final answer to the question apparently lies in fossils, not wrangling among different schools. The currently mainstream idea in palaeobotany is that angiosperms cannot have existed earlier than the Early Cretaceous. This 64-year-old stereotype was recently iterated again in 2017. However, another hard-to-ignore fact is that this view is challenged by increasing pre-Cretaceous fossil evidence of angiosperms as well as molecular clock estimates. Here, we report a Permian angiosperm, Yuzhoua gen. nov. from Henan Province, China. This fossil plant has enclosed ovules, a defining feature idiosyncratic of angiosperms. In addition, a conspicuous style is seen on the top of the ovary, underscoring its distinction from known fossil seeds in gymnosperms. The combination of the Permian (Palaeozoic) age and these two unique features of Yuzhoua indicates that angiosperms first appeared much earlier than widely accepted, implying a much longer history of flowering plants. The occurrence of four specimens preserved in various states and unique morphology of Yuzhoua are beyond the expectations of all known theories on plant evolution, shedding new light on a previously unknown aspect of plant evolution in geological history.