Premise of research. Early Cretaceous flowers recovered from Portugal and North America are some of the oldest and most informative angiosperm structures known. Analyses of this material provide a more direct basis for inferring floral structure and biology in early angiosperms than extrapolations based solely on extant taxa, and they have documented an unanticipated diversity of angiosperms, including the presence of many extinct forms, during the Early Cretaceous. The fossil flower described here from the Early Cretaceous of Portugal adds to the knowledge of this extinct diversity. Methodology. Coalified fossil flowers were extracted from unconsolidated sediments and cleaned with HF, HCl, and water. Details were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Phylogenetic relationships were evaluated by adding the fossil to a phylogenetic analysis of extant basal angiosperms based on morphological characters but constrained according to a topology based on molecular data. Pivotal results. A new genus and species, Catanthus dolichostemon, are described on the basis of the fossil flowers. The perianth consists of three thick sepal-like tepals in an outer whorl and six thinner petallike tepals in two inner whorls. The androecium consists of several whorls of stamens with long, broad filaments and anthers with extrorse dehiscence. Pollen is trichotomocolpate and possibly monocolpate. The gynoecium is superior and apocarpous, consisting of six or, rarely, five carpels. Analysis of the phylogenetic position of Catanthus suggests a relationship to Canellales and Magnoliales. Conclusions. Catanthus is a new Early Cretaceous magnoliid angiosperm for which the relationship to the two major clades of extant magnoliids (Laurales + Magnoliales or Canellales + Piperales) is not resolved securely. Catanthus adds to the evidence of substantial extinct diversity among early angiosperms, including the presence of extinct forms related to extant magnoliids, and it is consistent with a general pattern that angiosperm assemblages from the middle Albian and earlier are dominated by noneudicots.

中文翻译：

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[italic]Catanthus[/italic]，葡萄牙早白垩世已灭绝的木兰科植物

研究的前提。从葡萄牙和北美恢复的白垩纪早期花朵是已知的最古老、信息最丰富的被子植物结构之一。与仅基于现存分类群的推断相比，对这种材料的分析为推断早期被子植物的花结构和生物学提供了更直接的基础，并且他们记录了在白垩纪早期被子植物的意外多样性，包括许多已灭绝形式的存在。这里描述的来自葡萄牙早白垩世的化石花增加了对这种已灭绝多样性的了解。方法。从松散的沉积物中提取煤化化石花，并用 HF、HCl 和水清洗。使用扫描电子显微镜和同步辐射 X 射线断层显微术研究了细节。通过将化石添加到基于形态特征的现存基部被子植物的系统发育分析中来评估系统发育关系，但根据基于分子数据的拓扑结构进行约束。关键结果。在化石花的基础上描述了一个新的属和种 Catanthus dolichostemon。花被由一个外轮中的三个厚的萼片状花被片和两个内轮中的六个较薄的花瓣状花被片组成。雄蕊群由数个带有长而宽的花丝的雄蕊轮和外向开裂的花药组成。花粉是trichotomocolpate，可能是monocolpate。雌蕊上位且无果皮，由六个心皮或很少有五个心皮组成。对 Catanthus 的系统发育位置的分析表明与 Canellales 和 Magnoliales 的关系。结论。Catanthus 是一种新的早白垩世木兰科被子植物，其与现存木兰科（Laurales + Magnoliales 或 Canellales + Piperales）的两个主要进化枝的关系尚未得到妥善解决。Catanthus 增加了早期被子植物中大量灭绝多样性的证据，包括与现存木兰科相关的灭绝形式的存在，并且它与来自阿尔比斯中部和更早时期的被子植物组合以非双子叶植物为主的一般模式一致。