Practice question

Archaefructus, recovered from Liaoning Yixian Formation lower Cretaceous about 125 million years, interpreted as herbaceous aquatic early angiosperm bearing reproductive axes with spirally arranged carpels containing seeds and stamens beneath, lacking perianth whorl. Carpels closed yet foliate, ovules enclosed confirming angiosperm status despite primitive organization. It represents extinct stem lineage basal to crown group, not modern angiosperm, not earliest gymnosperm nor primitive bryophyte. Fossil illuminates aquatic herb hypothesis for origin, demonstrating that closed carpel evolved in lacustrine environments preceding showy flower evolution and supporting rapid diversification during Cretaceous.