Friday 12 August 2016

Euanthus panii: A flower from the Middle-Late Jurassic Jiulongshan Formation of Liaoning Province, China.

Flowering Plants, Angiosperms, are the dominant group of plants in almost all modern terrestrial ecosystems, but their origins remain somewhat obscure. The group rose to dominance early in the Cretaceous, and have only a pachy and debatable fossil record before this,  though molecular clock dating methods have suggested that Angiosperms are considerably older than Cretaceous in origin.

In a paper published in the journal Historical Biology on 16 March 2016, Zhong-Jian Liu of the Shenzhen Key Laboratory for Orchid Conservation and Utilization at the National Orchid Conservation Center of China and Orchid Conservation and Research Center of Shenzhen and Xin Wang of the State Key Laboratory of Palaeobiology and Stratigraphy at the Nanjing Institute of Geology and Palaeontology and the Palaeontological Center at Bohai University describe a well preserved flower from the Middle-Late Jurassic Jiulongshan Formation of Liaoning Province, China.

The specimen is described as Euanthus panii, where 'Euanthus' means 'real-flower' in Latin and 'panii' honours Kwang Pan, who collected the specimen and donated it to the Nanjing Institute of Geology and Palaeontology. Euanthus panii comprises a single flower on a split limestone block, with part and counterpart showing the adaxial and abaxial surfaces; the specimen is a compression with some coalified residue.

Euanthus panii and its details. Stereomicroscopy. (a, b) The flower in two facing parts, with sepals (S) and petals (P) radiating from the receptacle. The black arrows mark the distal of the style, and the blue arrow in (b) marks the stamen. (c) A sepal (S) is almost structureless between the two arrows, implying that it is attached to the receptacle (O) with its whole base. Enlarged from (a). Bar ¼ 1 mm. (d) Pentamerous receptacle with ovarian cavity (O) in its centre. Note the corners (arrows) of about 110 degrees. Bar = 0.5 mm. (e) Basal portion of the flower after degagement. Note spatial relationship among the ovary (O), style base, a possible filament stub (arrow), sepals (S) and petal (P). Bar = 1.0 mm. Liu & Wang (2016).

The flower is about 12mm long and 12.7mm wide, with pentamerous symmetry and short stout sepals alternating with longer petals. The androecium has dithecate anthers with in situ pollen grains, the gynoecium a long, slender hairy style and an unilocular ovary enclosing unitegmic ovules. Given past controversy about pre-Cretaceous Angiosperm fossils, Lui & Wang are cautious in their dating of the specimen, but are confident the rocks of the outcrop which produced it are at least 161.8 million years old.

See also... bodae: A herbaceous Angiosperm (Flowering Plant) from the Middle Jurassic of Inner Mongolia.                                  Angiosperms (Flowering Plants) are the dominant plants in almost all modern ecosystems, producing a wide variety of woody and herbaceous forms. The earliest Angiosperms are thought to have...
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