A Permian fossil may reveal the oldest known flowering-plant structure
Despite the importance and dominance of angiosperms ("flowering plants") in the current ecosystem, it is rather surprising that we know so little about their origin and early evolution. Paleobotanists have been making efforts to decipher these enigmas. Unfortunately, their efforts are characterized by an "unbroken record of failure," as Tom Harris put it.
The discovery of Permocarpelloides shuozhouensis, a fossil from the Early Permian of China, has significant implications for our understanding of the origin of flowering plants (angiosperms). This three-dimensional fossil contains three fruits, each with multiple ovules of varying sizes, arranged in a manner similar to an apocarpous gynoecium—similar to what scientists expect to see in angiosperms akin to the "First Flower" Archaefructus liaoningensis.
The presence of both free carpels and enclosed ovules in this fossil provides crucial evidence supporting the existence of angiosperms in the Early Permian, around 295 million years ago. This pushes back the timeline of angiosperm presence by at least 100 million years, challenging the previously held belief that angiosperms could not have existed prior to the Cretaceous period (145 to 66 million years ago).
The discovery of Permocarpelloides shuozhouensis also highlights the diversity within early angiosperms. The ovules and seeds found in the fossil demonstrate varying sizes, with larger ones potentially being seeds and smaller ones representing ovules at different stages of development. This observation is essential in plant systematics, as it serves as a distinguishing feature between angiosperms and gymnosperms, which have enclosed ovules.
Furthermore, the distinct morphological characteristics of the female organs in various angiosperm fossils, including Taiyuanostachya, Yuzhoua, Dengfengfructus, and Permocarpelloides, suggest a higher level of diversity among early angiosperms than previously assumed. This implies that our understanding of angiosperm evolution may still be incomplete, and there may be additional early fossil angiosperms waiting to be discovered in museum drawers or in ancient Permian strata.
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