A quarter of a billion years ago, life on Earth was almost extinct. As the continents collided and formed a single large landmass – the supercontinent of Pangea – the global climate changed. It got drier, especially inside. About 96 percent of all species that are polluting the oceans and 70 percent of the animals on land died in the so-called Great Permian Extinction. The ferns and mosses that had covered the land shrank, though some have survived and still exist in isolated pockets.
In the Devonian, before the Perm, seed plants began to develop. But, to the astonishment of the paleo-proposition, Permian sediment found in the Jordan at the Dead Sea shows that at this damn time, new groups of seed plants have even developed; three of them were indeed the oldest known pines. The other two died later.
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Plants and the extinction of Perm
Permian extinction is believed to have stretched over 100,000 years and was the world's most extreme extinction. Paleontologists are largely in agreement. They do not agree on much else, such as the cause, though recent considerations were less focused on a single event such as a comet impact and more on impulse issues, including the fact that creating the supercontinent led to climatic extremes.
We are It is not clear how many plant species met their creator during Permian extinction.
"Some estimates say 70 to 80 percent, but I do not know how reliable these numbers are," said Prof. Hans Kerp of the University of Münster, co-author of a paper on Permian extinction with Abdalla Abu Hamad, William A. DiMichele and Benjamin Bomfleur, said Haaretz.
Plants in the tropical regions seem to have been devastated, although in the extreme north (the boreal area) the effect was less pronounced.
No group of plants completely died when the global climate changed from a greenhouse world in the Perm to a greenhouse in the Triassic (the first period of the Mesozoic), says Kerp. The ferns and mosses have survived somewhere, it seems in higher latitudes, where the effects of large extinctions were usually less severe.
Gymnosperm seed plants were able to propagate happily in the Triassic; Among other things, they have internal vascular systems for water transport and were therefore better adapted to the usual, drier habitats. The surprise was that during the Permian, Gymnosperm's development was in a tropical area that had seasonality. Permian sediments were largely free of fossils, explains Kerp.
The climate on the Jordanian coast a quarter of a billion years ago was monsoonal, with a long dry season and a short rainy season, says Kerp. "This is indicated by the presence of fossil soils, typically with limestone layers and so-called iron pisolites, which normally form in regions with such a climate."
The typical Permian vegetation of ferns, giant boxes, mosses and their variety needs constant humidity to survive, so they would not be well beaten in this volatile environment. But even the environmental impact – the seasonality itself, the wet winter, the long dry summer – would have driven the development of plants, says the team, Kerp, Abu Hamad, DiMichele and Bomfleur.
Stressed environments susceptible to disturbances such as floods, erosion, and the like, force life forms to adapt and evolve or die out, Kerp points out.
In short, the results suggest that drought-prone tropical habitats, as in Jordan, served as an evolutionary cradle for the early diversification of plants.
One of the fossil plants found in the Permian layers of Jordan is none other than the pine tree fathers, the Podocarpaceae. It turns out that they evolved over a quarter of a billion years ago and survived the great Permian extinction, scientists say, after they unexpectedly found fossil branches of these trees in the Jordanian rocks.