Search of the First Flower


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Search of the First Flower

Post by Miyis » Tue Jan 31, 2006 5:08 pm

I think Angiosperm form in water.

In Search of the First Flower: A Jurassic Angiosperm, Archaefructus, from Northeast China

In Search of the First Flower: A Jurassic Angiosperm, Archaefructus, from Northeast China. Ge Sun, David L. Dilcher, Shaoling Zheng, and Zhekun Zhou
Science Nov 27 1998: 1692-1695.

Sun, * David L. Dilcher Shaoling Zheng, Zhekun Zhou

Angiosperm fruiting axes were discovered from the Upper Jurassic of China. Angiosperms are defined by carpels enclosing ovules, a character demonstrated in this fossil. This feature is lacking in other fossils reported to be earliest angiosperms. The fruits are small follicles formed from conduplicate carpels helically arranged. Adaxial elongate stigmatic crests are conspicuous on each carpel. The basal one-third of the axes bore deciduous organs of uncertain affinities. No scars of subtending floral organs are present to define the individual fertile parts as floral units, but the leaf-like structures subtending each axis define them as flowers. These fruiting axes have primitive characters and characters not considered primitive.

It has been thought that angiosperms first appeared about 130 million years ago in the Lower Cretaceous (1, 2). There are several recent reports of Triassic, Jurassic, and lowermost Cretaceous-aged fossils identified as angiosperms (3-7), but none of these reports can be accepted as conclusive evidence for the presence of angiosperms. Many reports of early angiosperms are based on pollen, leaves, and wood with vessels, none of which are definitive characters of angiosperms. Some are based on flowers and fruits that are too poorly preserved to demonstrate ovules or seeds enclosed in the carpels. The unique character of angiosperms is that the ovules are completely enclosed in a carpel. Here, we describe such early angiosperm fruits collected from the Upper Jurassic "Jianshangou Bed" in the lower part of the Yixian Formation of Huangbanjiegou village near Shangyuan Town of Beipiao City, western Liaoning Province, northeast China

Archaefructus liaoningensis Sun, Dilcher, Zheng et Zhou gen. et sp. nov. (A) Holotype, SZ0916; fruiting axes and remains of two subtending leaves. Scale bar, 5 mm. (B) Enlarged view of the carpels showing remains of the adaxial crest, abaxial venation, seeds in each carpel, and finger-like prominences. Scale bar, 5 mm. (C) Portion of a seed removed from a carpel, as viewed by scanning electron microscopy. Scale bar, 25 µm

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Post by Dr.Stein » Wed Feb 01, 2006 9:23 am

Life begins from water - Oparin :)

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