Department of Palaeobotany, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden;
Am J Bot. 2007 Dec;94(12):2041-53. doi: 10.3732/ajb.94.12.2041.
A charcoalified fossil flower, Potomacanthus lobatus gen. et sp. nov., is described from the Early Cretaceous (Early to Middle Albian) Puddledock locality, Virginia, USA. Internal floral structure was studied using nondestructive synchrotron-radiation x-ray tomographic microscopy (SRXTM). The flower is bisexual and trimerous. The perianth consists of two whorls of tepals. The androecium has two whorls of fertile stamens. Anthers open by two distally hinged valves. The gynoecium consists of a single carpel that is plicate in the style and ascidiate in the ovary and contains a single pendant ovule. The fossil flower shares many similarities with flowers of extant Lauraceae and is unlike flowers of other families of Laurales. However, the fossil flower also differs in detail from all extant or fossil Lauraceae, particularly in configuration of the androecium. The new taxon, together with previously described but more fragmentary material from the Puddledock locality, provides the earliest fossil record of plants more closely related to Lauraceae than to any other extant family. It reveals several derived morphological characters that are potential synapomorphies among extant representatives of the family Lauraceae and contributes to the growing evidence for an early diversification of Laurales before the end of the Early Cretaceous.
一种碳化的化石花朵，即 Potomacanthus lobatus 属和种，是在美国弗吉尼亚州早期白垩纪（早至中阿尔布期）的 Puddledock 地点发现的。使用非破坏性同步辐射 X 射线断层显微镜技术（SRXTM）对花的内部结构进行了研究。该花为两性花，具三基数。花被由两轮花被片组成。雄蕊群由两轮可育雄蕊组成。花药以两个远轴铰链的瓣开裂。雌蕊群由一个心皮组成，花柱具褶，子房具囊状，含有单个悬垂胚珠。该化石花与现生樟科的花有许多相似之处，与樟目其他科的花不同。然而，该化石花在细节上也与所有现生或化石樟科植物不同，特别是在雄蕊群的配置上。新分类群与此前在 Puddledock 地点描述的更为零碎的材料一起，提供了比任何其他现生科更接近樟科的植物的最早化石记录。它揭示了几个衍生的形态特征，这些特征可能是现生樟科代表之间的共同衍征，并为早白垩世末期之前的樟目早期多样化提供了越来越多的证据。
