The new records of Coniopteris (Dicksoniaceae, Filicales) with in-situ spores from the Middle Jurassic of northeastern China and its spatio-temporal distribution in China

The extinct fern genus Coniopteris Brongniart represents a common component of the Mesozoic dicksoniaceous ferns. New materials of Coniopteris preserved with both sterile and fertile pinnae, are described from the Middle Jurassic Haifanggou Formation in Beipiao of western Liaoning, Northeast China. Totally two species, i.e., C. burejensis and C. bella, were recognized. The gross morphology of the present specimens indicates that both the species were hemidimorphic in frond type. A detailed investigation on the in-situ spores of C. burejensis and C. bella shows that they are morphologically similar to the dispersed spores Deltoidospora perpusilla and D. cf. turgidorimasa, respectively. Additionally, based on available data on fossil records, the fossil diversity and spatiotemporal distribution pattern of Chinese Coniopteris are systematically reviewed and summarized. The results show that over sixty Coniopteris species have been recorded in China, ranging from the Early Jurassic to Early Cretaceous in time, and particularly flourished in two geological time intervals, i.e., the Middle Jurassic and the Early Cretaceous. Palaeogeographically, Coniopteris fossils were found throughout China in the Early Jurassic; and they mostly occurred in northern China during the Middle Jurassic; thereafter, they were restricted in northeastern China in the Early Cretaceous.