References
1 Fu, Q. et al. An unexpected noncarpellate epigynous flower from the Jurassic of China. eLife 7 , e38827, (2018).
2 Wang, X. The Dawn Angiosperms. Springer, Cham, Switzerland, 2018.
3 Hochuli, P. A. & Feist-Burkhardt, S. A boreal early cradle of angiosperms? angiosperm-like pollen from the Middle Triassic of the Barents Sea (Norway). Journal of Micropalaeontology 23 , 97-104, (2004).
4 Hochuli, P. A. & Feist-Burkhardt, S. Angiosperm-like pollen andAfropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland). Frontiers in Plant Science4 , 344, (2013).
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Figure captions
Fig. 1 A Jurassic half pollen grain and its details. c, columella; f, foot layer; t, tectum. A. A piece of rock fragment bearing the pollen grain (arrow). Bar = 0.1 mm. B. Detailed view of the pollen grain marked by the black arrow in Fig. 1A. The triangle points to the aperture. Bar = 2 μm. C. Detailed view of the region marked by white arrow in Fig. 1B, showing the foot layer, columellae, and tectum. Bar = 1 μm. D. Wall organization of the pollen grain, marked by black arrow in Fig. 1B, showing the heterogeneous foot layer and tectum. Bar = 1 μm. E. MFCFM image of the pollen grain showing separated foot layer and tectum. The triangle points to the aperture. Bar = 5 μm. F. MFCFM image of the pollen grain showing supratectal spines (arrows) on the tectum. The triangle points to the aperture. Bar = 5 μm. G. Detailed view of the three-layered pollen wall structure (tectum, columella, and foot layer), marked with yellow arrow in Fig. 1B. Bar = 1 μm. H. Risen and separated tectum near the margin of aperture, marked by blue arrow in Fig. 1B. Bar = 1 μm. I. Separated tectum in the pollen wall of Oryza sativa. Bar = 5 μm. Fig. 2 Comparison among the fluorescence spectra of the fossil pollen grain and spore/pollen of extant plants. A. Comparison between the fossil pollen grain and spore of ferns. Note one of the spectrum peaks (left) is distinct from those of extant ferns. B. Comparison between the fossil pollen grain and pollen grains of extant seed plants. Note one of the spectrum peaks (right) is distinct from those of seed plants. Fig. S1. Geographical position of the fossil locality, Daohugou Village, Ningcheng, Inner Mongolia, China. The rectangular region in the inset map of Northeast China is shown in detail in the main map, in which the position of Daohugou village (close to the junction among Liaoning, Hebei, and Inner Mongolia) is marked by the arrow. Fig. S2 General information of the fossil. A. A plant embedded in siltstone of the Jiulongshan Formation (Middle-Upper Jurassic). Bar = 1 cm. B. Detailed view of the area marked by arrow in Fig. S2a. Bar= 0.5 mm. C. Detailed view of the area marked by arrow in Fig. S2b, the arrow points to the source area of sample shown in Fig. 1. Bar= 0.1 mm. Fig. S3 TEM image showing a pollen grain of extant Oryza sativa(Poaceae) with separated foot layer and tectum. Bar = 1 μm.