Extended Data Fig. 6: Fossil cupules and cupule stalks of Caytonia sp.
From: Mesozoic cupules and the origin of the angiosperm second integument
a–i, Caytonia sp. from the Middle Jurassic of Yorkshire, UK. a, b, Flattened cupule-bearing structures showing subopposite cupule stalks or attachment scars in two ranks that lack evidence of a bract subtending each cupule. a, PP60606. b, PP60607. c–e, Small, possibly aborted, cupules at pollination stage showing the distinct lips. c, PP60608. d, PP60609. e, Note the parallel grooves leading to the micropylar canals on the lip of the cupule. PP60610. f, Flattened seed removed from a cupule. PP60611. g, Fractured mature cupule showing seeds with the micropyles of the two on the left oriented towards the base of the cupule. PP60612. h, i, Caytonia nathorsti8. h, Flattened cupule-bearing structure showing lateral cupules recurved towards the presumed upper (adaxial) surface. V.26661 (Natural History Museum, London). i, Portion of h showing the ridges on the presumed lower (abaxial) surface. j–l, Caytonia sp. from the Middle–Late Jurassic of Daohugou locality, eastern Inner Mongolia, China. j, k, Part and counterpart of a cupule containing eleven seeds arranged in two rows. See Fig. 3g for a three-dimensional reconstruction from segmented micro-CT data. B0441. l, Cupule showing the parallel grooves leading to the micropylar canals (arrow). B0440 (IVPP). Scale bars, 500 μm (a, c–g); 1 mm (b, h–l).
