Middle-Late Jurassic fossils from northeastern China reveal morphological stasis in the catkin-yew.
Middle-Late Jurassic fossils from northeastern China reveal morphological stasis in the catkin-yew.
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中国东北地区中晚侏罗世化石揭示了柳絮红豆杉的形态停滞
DOI：
10.1093/nsr/nwaa138
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发表时间：
2020-11
影响因子：
20.6
通讯作者：
Crane PR
中科院分区：
文献类型：
--
作者：
Dong C;Shi G;Herrera F;Wang Y;Herendeen PS;Crane PR
The Taxaceae, commonly known as the yews, are widely used in ornamental horticulture and are an important source of chemotherapeutic drugs (e.g. Paclitaxel). The Taxaceae have long been considered distinct from other conifers, based on their axillary seed-bearing structures that are very different from most conifer cones, consisting of an axis bearing a single terminal seed with a fleshy aril, subtended by several bracts [1]. Phylogenetic analyses based on molecular data recognize the Taxaceae sensu stricto as monophyletic comprising five genera [2]. Amentotaxus and Torreya are sister taxa, and together are sister to the Taxeae, which comprises Taxus, Pseudotaxus and Austrotaxus. Cephalotaxus is resolved as sister to Taxaceae sensu stricto. The Taxaceae sensu stricto comprise about 25 extant species, many of which have very restricted distributions and small population sizes, and are endangered in thewild [3]. Fossil evidence of Taxaceae is based mainly on isolated leaves or leafy shoots for which the reproductive structures are unknown. However, several more complete fossils with attached seed-bearing structures show that Taxaceae had diverged from other conifers by the earliest Jurassic and were probably diverse during the Jurassic and Cretaceous [4,5]. Here we add to knowledge of early Taxaceae based on fossils from the late Middle–early Late Jurassic Daohugou Bed (∼165–158 Ma) in eastern Inner Mongolia, northeastern China [6]. The material includes the terminal portion of a leafy shoot with attached seed-bearing structures (Fig. 1a and e), and a leafy shoot with two orders of branching in which each ultimate shoot has a terminal conical bud (Fig. 1b and f). These fossils (for detailed description and illustration see Supplementary Data) bear a striking resemblance to the leafy shoots and seedbearing structures of extant Amentotaxus (Fig. 1c, d and i). As in extant Amentotaxus, the leafy shoots in the Daohugou fossils spread more or less in a single plane; the leaves are linear-lanceolate and appear to be borne in two ranks, although they are decussately inserted (Fig. 1b and f). The leaves also have a raised mid-vein on the adaxial surface and two broad lateral stomatal bandson the abaxial surface. In the seed-bearing specimen from Daohugou, and also in extant Amentotaxus, each seed is borne singly and erect on a short, naked axis that arises in the axil of a vegetative leaf (Fig. 1g, h and j, and Supplementary Fig. 4). The seed is not visible in the Daohugou fossil, but this is often also the case in extant Amentotaxus, where the small, immature seeds are often completely, or almost completely, enclosed by the opposite and decussate bracts (Fig. 1i). In all the features that are preserved, the fossil material only differs from extant Amentotaxus in having shorter seed-bearing axes. All other extant genera of Taxaceae differ from the Daohugou fossils. Torreya has opposite to sub-opposite leaves, but its seed-bearing structures lack a distinct stalk. Austrotaxus, Pseudotaxus and Taxus have seed-bearing structures that arise singly from the axil of a normal vegetative leaf as in the Daohugou fossils, but their leaves are helically arranged and the seed-bearing stalks are very short and covered by dense scale leaves. A close relationship of the fossil material to extant Amentotaxus is also supported by phylogenetic analyses based on morphological characters of living and fossil Taxaceae (Supplementary Data). In an unconstrained analysis (Fig. 1k), and also an analysis with the relationships of extant Taxaceae constrained to the topology of the most recent molecular phylogeny (Fig. 1l), the Daohuguo fossils are resolved as sister taxa to extant Amentotaxus, withMarskea jurassica from the Middle Jurassic of Yorkshire, England [4,5] sister to both. The clade comprising Amentotaxus, the Daohuguo fossils and M. jurassica is defined by the naked seed stalks that each bear a single seed. It would therefore be reasonable to assign the Daohuguo fossils to the extant genusAmentotaxus, while also recognizing that there is currently insufficient information on pollen organs and other structures that could place it unequivocally in the crown group of the genus. The morphological distinctiveness of Taxaceae has been used to suggest they are a separate line of evolution fromother conifers [1], but evidence frommolecular phylogenetics [2], as well as other assessments [7], include Taxaceae sensu stricto
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影响因子：
1.9
作者：
HARRIS, TM
通讯作者：
HARRIS, TM
影响因子：
2.3
作者：
Friis, Else Marie;Crane, Peter R.;Pedersen, Kaj Raunsgaard
通讯作者：
Pedersen, Kaj Raunsgaard
系统发育学解决了种子植物的深层系统发育，并表明买麻藤目和被子植物之间的部分趋同或同质进化
DOI：
10.1098/rspb.2018.1012
发表时间：
2018-06-27
影响因子：
4.7
作者：
Ran, Jin-Hua;Shen, Ting-Ting;Wang, Xiao-Quan
通讯作者：
Wang, Xiao-Quan
影响因子：
--
作者：
FLORIN, R
通讯作者：
FLORIN, R