THE EARLY PHYLOGENETIC DIVERSIFICATION OF CORNALES: PERMINERALIZED CORNALEAN FRUITS FROM THE CAMPANIAN (UPPER CRETACEOUS) OF WESTERN NORTH AMERICA
THE EARLY PHYLOGENETIC DIVERSIFICATION OF CORNALES: PERMINERALIZED CORNALEAN FRUITS FROM THE CAMPANIAN (UPPER CRETACEOUS) OF WESTERN NORTH AMERICA
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DOI：
10.1086/692766
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发表时间：
2017-09-01
影响因子：
2.3
通讯作者：
Rothwell, Gar W.
中科院分区：
文献类型：
--
作者：
Atkinson, Brian A.;Stockey, Ruth A.;Rothwell, Gar W.
研究的前提。在不列颠哥伦比亚省温哥华岛上白垩纪(上坎帕尼亚)喷雾形成的单个钙质结核中发现了两个过矿化水果。这些化石为珊瑚目的系统发育多样化提供了额外的证据，这是最早的分叉星状线。标本制备采用醋酸纤维剥离技术。本文记述了玉米一新种Suciacarpa xiangae sp.Nov.的特征是基于保存完好的果实标本。该果由一个大的卵球形四眼厚壁内果皮表示。胚根横切面呈新月形，并伴有短的背侧萌发裂片。瓣膜由小的等径壁细胞和大量大的分泌腔组成。隔膜和中轴由横向排列的交织纤维和细长的巩膜组成。没有主要的中央维管束，但隔内散布着许多小束。该果每室顶着生一粒种子。另有一新的玉米分类群--万古瓦果盾壳属。ET sp.Nov.，也表现为单个光滑的四眼硬组织内果皮，由等径和少数细长的硬果组成，具有短的萌发瓣膜，每室一粒种子，缺乏中央维管束。由于性状的独特组合，本研究中所描述的这两个果实代表了两个新的玉米类群--香菇(S.xiangae sp.)11月和温哥华链霉菌S.vancouverensis gen.ET sp.11月这些果实表现出无形性和多形性的马赛克，至少出现在两个不同的主要山茱蒲科/藤科和睡莲科/马蹄草科/梧桐科的科中。从这些分类群和晚白垩世的其他珊瑚中发现的形态多样性表明，坎帕尼亚是珊瑚目最初系统发育多样化的重要时期。
Premise of research. Two permineralized fruits have been found within a single calcareous concretion from the Upper Cretaceous (upper Campanian) Spray Formation of Vancouver Island, British Columbia. These fossils provide additional evidence for the initial phylogenetic diversification of Cornales, the earliest diverging asterid lineage.Methodology. Specimens were prepared using the cellulose acetate peel technique.Pivotal results. A new cornalean species, Suciacarpa xiangae sp. nov., is characterized on the basis of a well-preserved fruit specimen. This fruit is represented by a large ovoid tetralocular sclerenchymatous endocarp. Locules are crescent shaped in transverse section and accompanied by short dorsal germination valves. Valves consist of small isodiametric sclereids as well as a large number of large secretory cavities. The septum and central axis are composed of transversely oriented and interwoven fibers and elongate sclereids. There is no major central vascular bundle; however, there are numerous small bundles scattered within the septa. This fruit has one apically attached seed per locule. An additional cornalean taxon-Sheltercarpa vancouverensis gen. et sp. nov., also represented by a single smooth tetralocular sclerenchymatous endocarp-consists of isodiametric and a few elongate sclereids, with short germination valves, one seed per locule, and lacks a central vascular bundle.Conclusions. Because of unique combinations of characters, the two fruits described in this study represent two new cornalean taxa, S. xiangae sp. nov. and S. vancouverensis gen. et sp. nov. These fruits display mosaics of apomorphic and plesiomorphic characters that occur in families of at least two different major cornalean clades: Cornaceae/Alangiaceae and Nyssaceae/Mastixiaceae/Davidiaceae. The morphological diversity seen in these taxa and other cornaleans from the Late Cretaceous suggests that the Campanian was an important time for the initial phylogenetic diversification of Cornales.