Endemic fossil seed plants from China and a reassessment of coniferophyte phylogeny

Recent palaeobotanical studies have provided new and important evidence on Chinese fossil plants. The majority of these fossils are distinct from fossil floras known from other geographical regions. However, remarkably few of these fossil plants have been successfully incorporated into cladistic analyses, to assess their importance on evolutionary relationships among major plant groups. For the first time our investigation incorporates three endemic Chinese fossil plant species into a cladistic analysis of the seed plants. These plants have been documented and reconstructed in detailed investigations of Palaeozoic coal balls from the Taiyuan Formation and are named Shanxioxylon sinensis, Shanxioxylon taiyuanensis and Pennsylvanioxylon tianii respectively. Previous investigations indicate that these plants belong to the now extinct Cordaitalean seed plants although they share many features with certain fossil conifers. As such, they are likely to be of significance to the ongoing and currently unresolved debate concerning coniferophyte phylogeny.