L. H. Bailey Hortorium, 462 Mann Library, Cornell University, Ithaca, New York 14853-4301.
Am J Bot. 1998 Sep;85(9):1273-88.
Two taxa of cupulate magnoliid fossil flowers, Cronquistiflora and Detrusandra, are described from the Late Cretaceous (Turonian, ∼90 million years before present [MYBP]) Raritan (or lower Magothy) Formation of New Jersey. The fossil taxa are represented by flowers at various stages of development, associated fragments of cup-shaped floral receptacles with attached anthers, and isolated anthers. Both taxa have laminar stamens with adaxial thecae and valvate dehiscence. Pollen is boat-shaped and foveolate in anthers associated with Cronquistiflora and spherical with reticulate ornamentation in Detrusandra. Cup-shaped receptacles are externally bracteose in both taxa. The receptacle of Cronquistiflora is broader than the campanulate one of Detrusandra. Cronquistiflora also has more carpels (∼50 in a spiral vs. ∼5 in a whorl or tight spiral). In Detrusandra the carpels are surrounded by dorsiventrally flattened structures (pistillodes?) that are remote from the attachment of the stamens near the distal rim of the receptacular cupule. Detrusandra stigmas are rounded and bilobed, while those of Cronquistiflora, although bilateral in symmetry, are somewhat peltate. The fossil taxa share prominent characters with extant cupulate magnoliids (e.g., Eupomatia, Calycanthus), but also share characters with other magnoliids including Winteraceae. These fossils represent taxa that are character mosaics relative to currently recognized families. Inclusion of these fossils in existing data matrices and ensuing phylogenetic analyses effect changes in tree topologies consistent with their mosaicism relative to modern taxa. But such analyses do not definitively demonstrate the affinities of the fossils other than illustrating that these fossils are generalized magnoliids. Additional analysis of modern and fossil magnoliids is necessary to fully appreciate the phylogenetic significance and positions of these fossil taxa. However, the results of the phylogenetic analyses do introduce the possibility that extinct taxa of Magnoliales with cupulate floral receptacles were transitional between basal angiosperms and those with tricolpate pollen. The fossils provide insights into the timing of evolution of character complexes now associated with coleopteran pollination.
描述了来自新泽西州晚白垩世（Turonian，距今约 9000 万年）拉特纳（或下部 Magothy）组的两种杯状木兰类化石花，即 Cronquistiflora 和 Detrusandra。化石类群代表了处于不同发育阶段的花朵，以及带有附着花药的杯状花托的碎片和分离的花药。这两个类群都具有具背腹面药室的片状雄蕊，并且具有镊合状开裂。与 Cronquistiflora 相关的花粉在花药中呈船形且具凹坑，而在 Detrusandra 中则呈球形且具网状纹饰。在这两个类群中，杯状花托在外部都具苞片。Cronquistiflora 的花托比 Detrusandra 的钟状花托宽。Cronquistiflora 还具有更多的心皮（约 50 个在螺旋状，而 Detrusandra 中约 5 个在心皮轮或紧螺旋状）。在 Detrusandra 中，心皮被背腹压扁的结构（胎座？）包围，这些结构远离位于花托杯状杯的远端边缘处的花药的附着处。Detrusandra 的柱头为圆形且具 2 裂，而 Cronquistiflora 的柱头虽然在对称性上是双侧的，但有些盾形。化石类群与现存的杯状木兰类（例如，Eupomatia、Calycanthus）具有显著的特征，但也与包括 Winteraceae 在内的其他木兰类具有共同特征。这些化石代表了与目前公认的科相比具有嵌合体特征的类群。将这些化石纳入现有的数据矩阵并进行随后的系统发育分析会导致树拓扑结构发生变化，这些变化与它们相对于现代类群的嵌合体特征一致。但是，这些分析并不能确定化石的亲缘关系，而只是表明这些化石是广义的木兰类。需要对现代和化石木兰类进行进一步分析，才能充分了解这些化石类群的系统发育意义和位置。然而，系统发育分析的结果确实提出了这样一种可能性，即具有杯状花托的 Magnoliales 灭绝类群在基部被子植物和具三孔花粉的被子植物之间具有过渡性。这些化石为与鞘翅目传粉相关的特征复合体的进化时间提供了见解。
