Sunday, January 15, 2012

Cystopteris viridula was born in the Pangea supercontinent

The first dinosaurs were fed on its fronds

Its present distribution in center and south of America, in North Africa, in southwest of Europe and in the islands of the Macaronesia clearly indicate in what moment of the evolution of the continents Cystopteris viridula was formed. It is one of oldest fern of the Earth and it belongs to the Athyriaceae family. The supercontinent Pangaea was its cradle makes about 230 million years during the Upper Triassic. Its appearance on the Earth agreed with the one of the first dinosaurs after the Massive Extinction of the Permian-Triassic, happened makes 250 million years, in which 90% of the species were extinguished.

Several Cystopteris viridula next to a unit of Greenovia aurea in a very humid volcanic rock wall located in the North face of the Pico del Teide to 1440 msnm. I recommend to extend the photos with a double click.

It makes about 220 million years, during the Upper Triassic, the supercontinent Pangaea began to disintegrate itself, forming a great crack that divided it in two continents: Laurasia and Gondwana with the Ocean of Tetis among them. The Cystopteris viridula fern already took about 10 million years on the Earth and lived in all that one vast region that enjoyed a warm and humid climate. The cracking of Pangaea fragmented its population between both new great supercontinents.

Cystopteris viridula at the beginning of May in the humid crack of a volcanic rock oriented towards the north in the Island of Tenerife.

During the following million years the supercontinent Laurasia was divided in two parts: North America that went moving towards the northwest and Eurasia towards the northeast, forming among them the Atlantic Ocean.

 Another Cystopteris viridula bringing forth new fronds in May vigorously.

It makes about 150 million years also Gondwana began to disintegrate itself in new continents. At first meetings South America and Africa cracked, but in a moment they separated. The tectonic plate of South America went moving quickly towards the west, while Africa traveled slowly towards the north approaching Eurasia and narrowing the Ocean of Tetis that diminished much its extension and happened to be the Sea of Tetis.

 Fronds of Cystopteris viridula that can get to measure up to 40 centimeters, although those of the image they do not surpass the 15 centimeters. The petiole is shorter than the lamina, which is ovate-lanceolate and bipennate.

The rest of Gondwana, the great tectonic plate formed by India-Madagascar-Antarctic-Australia soon cracked in two subcontinents. On the one hand the block formed by Madagascar and India that at first traveled together towards the northeast and soon separated, being run aground Madagascar to few kilometers of Africa, while India moved quickly towards the north until colliding violently with the tectonic plate of Asia and forming the Mountain range of the Himalayas. And finally the other block formed by the Antarctic and Australia that during several million years moved meetings towards the east and soon separated. The tectonic plate of Australia continued traveling single towards the east and the Antarctic went towards the South Pole.

 Ovate-lanceolate pinnae with the apex slightly caudate or acuminate. The pinnulae have showy nerves of darker green color.

The insertion of pinnae in rachis is oposite or alternate. The pinnae are oblong, whole and cuneate in the base.

The pinnules have teeth with the tip usually emarginate, ie with a tiny notch, especially in the more distal teeth each pinnula. The secondary veins ending in the heart of the notch or emargination.

In underside of this frond the tiny still immature sori can be seen. They belong to a unit that lives in Puerto de Izaña of Tenerife Island to about 2000 msnm.

Mature sori of Cystopteris viridula. They are very small and little showy, that is to say, very discreet. They are covered by a white ovate to suborbicular indusium with glandular hairs or rarely glabrous. Each sorus contains one to five sporangia in the form of black small balls. 

Near image of mature sporangia. When the sensors of humidity and temperature of the Cystopteris viridula detect that the suitable conditions occur to disperse spores, the small black sporangia will unfold violently as small catapults and will send spores more far possible of their mother to colonize new territories and to perpetuate therefore the species. In the image can be seen sori with a single sporangium, with two and with three. This low number of sporangia is a typical characteristic of all the Cystopteris. 

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