Friday, February 24, 2012

Is Another Mass Extinction Event on the Way?

English: K/T extinction event theory. An artis...Image via WikipediaIs Another Mass Extinction Event on the Way?: Why have mass extinctions of species occurred since the late Proterozoic (from 580 million years ago) and repeatedly through the Phanerozoic? Integral to these extinctions were abrupt changes in the physical and chemical properties of the atmosphere, ocean and land, inducing environmental changes at a pace to which many species could not adapt.

The best documented example to date is the 65 million years-old K-T boundary asteroid impact and extinction event. But several other mass extinctions were associated with volcanic eruptions and asteroid/comet impacts (see Figure 1).

Instantaneous effects of impacts (initial fireball flash as the asteroid or comet enters the atmosphere, crater explosion, seismic shock, tsunami waves, incandescent ejecta, dust plumes, greenhouse gas release from carbon-rich limestone and shale) occurred over periods ranging from seconds to weeks and months.

As shown in figure 1, Phanerozoic history (since about 540 million years ago) is marked with a number of mass extinction events. About 80% of genera were lost at the ~251 Ma Permian-Triassic boundary event. This was a consequence of both volcanic eruptions (known as the Siberian Norilsk traps) and an asteroid impact near Araguinha, Brazil (Araguinha: 40 km-diameter; 252.7+/-3.8 Ma).

Musnah atau Bertahan Hidup? 



P.590 - §1 Early evolutionary man is not a colorful creature. In general, these primitive mortals are cave dwellers or cliff residents. They also build crude huts in the large trees. Before they acquire a high order of intelligence, the planets are sometimes overrun with the larger types of animals. But early in this era mortals learn to kindle and maintain fire, and with the increase of inventive imagination and the improvement in tools, evolving man soon vanquishes the larger and more unwieldy animals. The early races also make extensive use of the larger flying animals. These enormous birds are able to carry one or two average-sized men for a nonstop flight of over five hundred miles. On some planets these birds are of great service since they possess a high order of intelligence, often being able to speak many words of the languages of the realm. These birds are most intelligent, very obedient, and unbelievably affectionate. Such passenger birds have been long extinct on Urantia, but your early ancestors enjoyed their services.
P.615 - §5 But if this universe rebel against the reality of truth and goodness refuses to approve the verdict, and if the guilty one knows in his heart the justice of his condemnation but refuses to make such confession, then must the execution of sentence be delayed in accordance with the discretion of the Ancients of Days. And the Ancients of Days refuse to annihilate any being until all moral values and all spiritual realities are extinct, both in the evildoer and in all related supporters and possible sympathizers.
P.676 - §2 Lime-secreting algae were widespread. There existed thousands of species of the early ancestors of the corals. Sea worms were abundant, and there were many varieties of jellyfish which have since become extinct. Corals and the later types of sponges evolved. The cephalopods were well developed, and they have survived as the modern pearly nautilus, octopus, cuttlefish, and squid.
P.685 - §2 The closing epochs of the preceding era were indeed the age of frogs, but these ancestors of the land vertebrates were no longer dominant, having survived in greatly reduced numbers. Very few types outlived the rigorous trials of the preceding period of biologic tribulation. Even the spore-bearing plants were nearly extinct.
P.687 - §4 These massive creatures became less active and strong as they grew larger and larger; but they required such an enormous amount of food and the land was so overrun by them that they literally starved to death and became extinct--they lacked the intelligence to cope with the situation.
P.691 - §2 The wading and swimming prebirds of earlier ages had not been a success in the air, nor had the flying dinosaurs. They were a short-lived species, soon becoming extinct. They, too, were subject to the dinosaur doom, destruction, because of having too little brain substance in comparison with body size. This second attempt to produce animals that could navigate the atmosphere failed, as did the abortive attempt to produce mammals during this and a preceding age.
P.695 - §2 Marked changes were taking place in the fauna of the planet. The sea life was undergoing great modification; most of the present-day orders of marine life were in existence, and foraminifers continued to play an important role. The insect life was much like that of the previous era. The Florissant fossil beds of Colorado belong to the later years of these far-distant times. Most of the living insect families go back to this period, but many then in existence are now extinct, though their fossils remain.
P.695 - §3 On land this was pre-eminently the age of mammalian renovation and expansion. Of the earlier and more primitive mammals, over one hundred species were extinct before this period ended. Even the mammals of large size and small brain soon perished. Brains and agility had replaced armor and size in the progress of animal survival. And with the dinosaur family on the decline, the mammals slowly assumed domination of the earth, speedily and completely destroying the remainder of their reptilian ancestors.
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