Middle-Late Jurassic fossils from Northeast China confirm the affiliation of Umaltolepis seed-bearing structures and Pseudotorellia leaves

Abstract

Umaltolepis seed-bearing structures and Pseudotorellia leaves were considered to be produced by the same plant according to their consistent association in the same bed and similarities in cuticular structures. Here we describe new fossils of Umaltolepis and Pseudotorellia based on well-preserved materials from the Middle-Late Jurassic Daohugou Bed in eastern Inner Mongolia, Northeast China. Umaltolepis zhoui sp. nov. is an umbrella-like, four-lobed cupule that was borne on a stalk at the tip of a short shoot. The stalk is cylindrical, with a prominent cup-like flange situated at the tip of the stalk and below the cupule. The short shoot bears growth cycles consisting of alternating pseudo-whorled bud scales and abscission scars. The cupule lobes are resinous, having sparse, longitudinally oriented stomata. Pseudotorellia zhoui sp. nov. is established based on a two-order leafy shoot and isolated leaves. The ultimate short shoot bears terminal clustered strap-shaped leaves, and alternating pseudo-whorled bud scales and abscission scars on surface. Leaves have acute apex, cuneate base; each bearing 4 to 8 longitudinal parallel veins. Abaxial cuticle has sparse, longitudinally to leaf margin oriented stomata which are arranged in 1–3 discontinuous files in the stomatal bands. The co-occurrence of U. zhoui and P. zhoui in the Daohugou Bed and their similarities in cuticular structures and morphology of attached short shoots further confirm that Umaltolepis and Pseudotorellia are produced by the same plant. These fossils also provide new evidence for a close relationship between the Mesozoic Umaltolepis-Pseudotorellia plant and living Ginkgo.