Ponder This:

4. THE GREAT LAND-EMERGENCE STAGE THE VEGETATIVE LAND-LIFE PERIOD THE AGE OF FISHES

59:4.9  250,000,000 years ago witnessed the appearance of the fish family, the vertebrates, one of the most important steps in all prehuman evolution.

59:4.10  The arthropods, or crustaceans, were the ancestors of the first vertebrates. The forerunners of the fish family were two modified arthropod ancestors; one had a long body connecting a head and tail, while the other was a backboneless, jawless prefish. But these preliminary types were quickly destroyed when the fishes, the first vertebrates of the animal world, made their sudden appearance from the north.

59:4.11  Many of the largest true fish belong to this age, some of the teeth-bearing varieties being twenty-five to thirty feet long; the present-day sharks are the survivors of these ancient fishes. The lung and armored fishes reached their evolutionary apex, and before this epoch had ended, fishes had adapted to both fresh and salt waters.

59:4.12  Veritable bone beds of fish teeth and skeletons may be found in the deposits laid down toward the close of this period, and rich fossil beds are situated along the coast of California since many sheltered bays of the Pacific Ocean extended into the land of that region.

59:4.13  The earth was being rapidly overrun by the new orders of land vegetation. Heretofore few plants grew on land except about the water's edge. Now, and suddenly, the prolific fern family appeared and quickly spread over the face of the rapidly rising land in all parts of the world. Tree types, two feet thick and forty feet high, soon developed; later on, leaves evolved, but these early varieties had only rudimentary foliage. There were many smaller plants, but their fossils are not found since they were usually destroyed by the still earlier appearing bacteria.

59:4.14  As the land rose, North America became connected with Europe by land bridges extending to Greenland. And today Greenland holds the remains of these early land plants beneath its mantle of ice.

59:4.15  240,000,000 years ago the land over parts of both Europe and North and South America began to sink. This subsidence marked the appearance of the last and least extensive of the Devonian floods. The arctic seas again moved southward over much of North America, the Atlantic inundated a large part of Europe and western Asia, while the southern Pacific covered most of India. This inundation was slow in appearing and equally slow in retreating. The Catskill Mountains along the west bank of the Hudson River are one of the largest geologic monuments of this epoch to be found on the surface of North America.

59:4.16  230,000,000 years ago the seas were continuing their retreat. Much of North America was above water, and great volcanic activity occurred in the St. Lawrence region. Mount Royal, at Montreal, is the eroded neck of one of these volcanoes. The deposits of this entire epoch are well shown in the Appalachian Mountains of North America where the Susquehanna River has cut a valley exposing these successive layers, which attained a thickness of over 13,000 feet.

59:4.17  The elevation of the continents proceeded, and the atmosphere was becoming enriched with oxygen. The earth was overspread by vast forests of ferns one hundred feet high and by the peculiar trees of those days, silent forests; not a sound was heard, not even the rustle of a leaf, for such trees had no leaves.

59:4.18  And thus drew to a close one of the longest periods of marine-life evolution, the age of fishes. This period of the world's history lasted almost fifty million years; it has become known to your researchers as the Devonian.

 

5. THE CRUSTAL-SHIFTING STAGE THE FERN-FOREST CARBONIFEROUS PERIOD THE AGE OF FROGS

59:5.1  The appearance of fish during the preceding period marks the apex of marine-life evolution. From this point onward the evolution of land life becomes increasingly important. And this period opens with the stage almost ideally set for the appearance of the first land animals.

59:5.2  220,000,000 years ago many of the continental land areas, including most of North America, were above water. The land was overrun by luxurious vegetation; this was indeed the age of ferns. Carbon dioxide was still present in the atmosphere but in lessening degree.

59:5.3  Shortly thereafter the central portion of North America was inundated, creating two great inland seas. Both the Atlantic and Pacific coastal highlands were situated just beyond the present shore lines. These two seas presently united, commingling their different forms of life, and the union of these marine fauna marked the beginning of the rapid and world-wide decline in marine life and the opening of the subsequent land-life period.

59:5.4  210,000,000 years ago the warm-water arctic seas covered most of North America and Europe. The south polar waters inundated South America and Australia, while both Africa and Asia were highly elevated.

59:5.5  When the seas were at their height, a new evolutionary development suddenly occurred. Abruptly, the first of the land animals appeared. There were numerous species of these animals that were able to live on land or in water. These air-breathing amphibians developed from the arthropods, whose swim bladders had evolved into lungs.

59:5.6  From the briny waters of the seas there crawled out upon the land snails, scorpions, and frogs. Today frogs still lay their eggs in water, and their young first exist as little fishes, tadpoles. This period could well be known as the age of frogs

59:5.7  Very soon thereafter the insects first appeared and, together with spiders, scorpions, cockroaches, crickets, and locusts, soon overspread the continents of the world. Dragon flies measured thirty inches across. One thousand species of cockroaches developed, and some grew to be four inches long.

59:5.8  Two groups of echinoderms became especially well developed, and they are in reality the guide fossils of this epoch. The large shell-feeding sharks were also highly evolved, and for more than five million years they dominated the oceans. The climate was still mild and equable; the marine life was little changed. Fresh-water fish were developing and the trilobites were nearing extinction. Corals were scarce, and much of the limestone was being made by the crinoids. The finer building limestones were laid down during this epoch.

59:5.9  The waters of many of the inland seas were so heavily charged with lime and other minerals as greatly to interfere with the progress and development of many marine species. Eventually the seas cleared up as the result of an extensive stone deposit, in some places containing zinc and lead.

59:5.10  The deposits of this early Carboniferous age are from 500 to 2,000 feet thick, consisting of sandstone, shale, and limestone. The oldest strata yield the fossils of both land and marine animals and plants, along with much gravel and basin sediments. Little workable coal is found in these older strata. These depositions throughout Europe are very similar to those laid down over North America.

59:5.11  Toward the close of this epoch the land of North America began to rise. There was a short interruption, and the sea returned to cover about half of its previous beds. This was a short inundation, and most of the land was soon well above water. South America was still connected with Europe by way of Africa.

59:5.12  This epoch witnessed the beginning of the Vosges, Black Forest, and Ural mountains. Stumps of other and older mountains are to be found all over Great Britain and Europe.

59:5.13  200,000,000 years ago the really active stages of the Carboniferous period began. For twenty million years prior to this time the earlier coal deposits were being laid down, but now the more extensive coal-formation activities were in process. The length of the actual coal-deposition epoch was a little over twenty-five million years.

59:5.14  The land was periodically going up and down due to the shifting sea level occasioned by activities on the ocean bottoms. This crustal uneasiness—the settling and rising of the land—in connection with the prolific vegetation of the coastal swamps, contributed to the production of extensive coal deposits, which have caused this period to be known as the Carboniferous. And the climate was still mild the world over.

59:5.15  The coal layers alternate with shale, stone, and conglomerate. These coal beds over central and eastern United States vary in thickness from forty to fifty feet. But many of these deposits were washed away during subsequent land elevations. In some parts of North America and Europe the coal-bearing strata are 18,000 feet in thickness.

59:5.16  The presence of roots of trees as they grew in the clay underlying the present coal beds demonstrates that coal was formed exactly where it is now found. Coal is the water-preserved and pressure-modified remains of the rank vegetation growing in the bogs and on the swamp shores of this faraway age. Coal layers often hold both gas and oil. Peat beds, the remains of past vegetable growth, would be converted into a type of coal if subjected to proper pressure and heat. Anthracite has been subjected to more pressure and heat than other coal.

59:5.17  In North America the layers of coal in the various beds, which indicate the number of times the land fell and rose, vary from ten in Illinois, twenty in Pennsylvania, thirty-five in Alabama, to seventy-five in Canada. Both fresh- and salt-water fossils are found in the coal beds.

59:5.18  Throughout this epoch the mountains of North and South America were active, both the Andes and the southern ancestral Rocky Mountains rising. The great Atlantic and Pacific high coastal regions began to sink, eventually becoming so eroded and submerged that the coast lines of both oceans withdrew to approximately their present positions. The deposits of this inundation average about one thousand feet in thickness.

59:5.19  190,000,000 years ago witnessed a westward extension of the North American Carboniferous sea over the present Rocky Mountain region, with an outlet to the Pacific Ocean through northern California. Coal continued to be laid down throughout the Americas and Europe, layer upon layer, as the coastlands rose and fell during these ages of seashore oscillations.

59:5.20  180,000,000 years ago brought the close of the Carboniferous period, during which coal had been formed all over the world—in Europe, India, China, North Africa, and the Americas. At the close of the coal-formation period North America east of the Mississippi valley rose, and most of this section has ever since remained above the sea. This land-elevation period marks the beginning of the modern mountains of North America, both in the Appalachian regions and in the west. Volcanoes were active in Alaska and California and in the mountain-forming regions of Europe and Asia. Eastern America and western Europe were connected by the continent of Greenland.

59:5.21  Land elevation began to modify the marine climate of the preceding ages and to substitute therefor the beginnings of the less mild and more variable continental climate.

59:5.22  The plants of these times were spore bearing, and the wind was able to spread them far and wide. The trunks of the Carboniferous trees were commonly seven feet in diameter and often one hundred and twenty-five feet high. The modern ferns are truly relics of these bygone ages.

59:5.23  In general, these were the epochs of development for fresh-water organisms; little change occurred in the previous marine life. But the important characteristic of this period was the sudden appearance of the frogs and their many cousins. The life features of the coal age were ferns and frogs.

 

6. THE CLIMATIC TRANSITION STAGE - THE SEED-PLANT PERIOD - THE AGE OF BIOLOGIC TRIBULATION

59:6.1  This period marks the end of pivotal evolutionary development in marine life and the opening of the transition period leading to the subsequent ages of land animals.

59:6.2  This age was one of great life impoverishment. Thousands of marine species perished, and life was hardly yet established on land. This was a time of biologic tribulation, the age when life nearly vanished from the face of the earth and from the depths of the oceans. Toward the close of the long marine-life era there were more than one hundred thousand species of living things on earth. At the close of this period of transition less than five hundred had survived.

59:6.3  The peculiarities of this new period were not due so much to the cooling of the earth's crust or to the long absence of volcanic action as to an unusual combination of commonplace and pre-existing influences—restrictions of the seas and increasing elevation of enormous land masses. The mild marine climate of former times was disappearing, and the harsher continental type of weather was fast developing.

59:6.4  170,000,000 years ago great evolutionary changes and adjustments were taking place over the entire face of the earth. Land was rising all over the world as the ocean beds were sinking. Isolated mountain ridges appeared. The eastern part of North America was high above the sea; the west was slowly rising. The continents were covered by great and small salt lakes and numerous inland seas which were connected with the oceans by narrow straits. The strata of this transition period vary in thickness from 1,000 to 7,000 feet.

59:6.5  The earth's crust folded extensively during these land elevations. This was a time of continental emergence except for the disappearance of certain land bridges, including the continents which had so long connected South America with Africa and North America with Europe.

59:6.6  Gradually the inland lakes and seas were drying up all over the world. Isolated mountain and regional glaciers began to appear, especially over the Southern Hemisphere, and in many regions the glacial deposit of these local ice formations may be found even among some of the upper and later coal deposits. Two new climatic factors appeared—glaciation and aridity. Many of the earth's higher regions had become arid and barren.

59:6.7  Throughout these times of climatic change, great variations also occurred in the land plants. The seed plants first appeared, and they afforded a better food supply for the subsequently increased land-animal life. The insects underwent a radical change. The resting stages evolved to meet the demands of suspended animation during winter and drought.

59:6.8  Among the land animals the frogs reached their climax in the preceding age and rapidly declined, but they survived because they could long live even in the drying-up pools and ponds of these far-distant and extremely trying times. During this declining frog age, in Africa, the first step in the evolution of the frog into the reptile occurred. And since the land masses were still connected, this prereptilian creature, an air breather, spread over all the world. By this time the atmosphere had been so changed that it served admirably to support animal respiration. It was soon after the arrival of these prereptilian frogs that North America was temporarily isolated, cut off from Europe, Asia, and South America.

59:6.9  The gradual cooling of the ocean waters contributed much to the destruction of oceanic life. The marine animals of those ages took temporary refuge in three favorable retreats: the present Gulf of Mexico region, the Ganges Bay of India, and the Sicilian Bay of the Mediterranean basin. And it was from these three regions that the new marine species, born to adversity, later went forth to replenish the seas.

59:6.10  160,000,000 years ago the land was largely covered with vegetation adapted to support land-animal life, and the atmosphere had become ideal for animal respiration. Thus ends the period of marine-life curtailment and those testing times of biologic adversity which eliminated all forms of life except such as had survival value, and which were therefore entitled to function as the ancestors of the more rapidly developing and highly differentiated life of the ensuing ages of planetary evolution.

59:6.11  The ending of this period of biologic tribulation, known to your students as the Permian, also marks the end of the long Paleozoic era, which covers one quarter of the planetary history, two hundred and fifty million years.

59:6.12  The vast oceanic nursery of life on Urantia has served its purpose. During the long ages when the land was unsuited to support life, before the atmosphere contained sufficient oxygen to sustain the higher land animals, the sea mothered and nurtured the early life of the realm. Now the biologic importance of the sea progressively diminishes as the second stage of evolution begins to unfold on the land.

59:6.13  [Presented by a Life Carrier of Nebadon, one of the original corps assigned to Urantia.]

Related Reference

 

Introduction:

At the end of the Permian period, the world was becoming increasingly warm (Newell 1953). Along with this rise in temperature, much of the ocean's water evaporated, causing a drop in sea level of up to 200 meters (Gall 1998). In addition, the continents converged to form the super-continent Pangea and super-ocean Panthalassa. By examining the structure and number of stomata on fossilized plants, scientists have concluded that Carbon Dioxide levels were much Higher and atmospheric Oxygen levels were much lower than those of today (Gall1998).

The Permo-triassic Boundary (PTB) featured the largest extinction the world has ever experienced. Although Mass extinctions have occurred in the past, this particular occurrence is remarkable in that it took place in a relatively short period of time. Scientists estimate that approximately 85% of all marine species (predominately invertebrates) and 70% of all terrestrial species went extinct in less than one million years (Bowring 1998). Braciopods by far suffered the largest casualties, but other victims include Acritarchs, Archaeocyathids, Molluscs, Echinoderms, Gusulinid Foraminifera, Corals, Diatoms, Dinoflagellates, Stromatoporoids, and Trilobites (Hooper Virtual Palaentological Museum 1999). So great was this die-out that fungal species were temporarily the dominant form of terrestrial life (Monastersky 1996). Causes of this catastrophe are yet unknown, but several theories have been suggested. This project, created by Audrey Johnson and Doug Blevins, seeks to present and examine these ideas.

Theories of Causes:

Many theories have been presented for the cause of the Permian - Triassic Extinction. These include volcanism, plate tectonics, anoxia of oceans, super nova explosions, severe weather, changes in sea level and atmospheric gas levels, climate change, and collision with a meteorite or comet. Here are these ides in more detail:

Collision of a Meteorite of Comet and Severe Weather patterns:

It has also been proposed that such a collision would heat up ocean waters enough to produce "hypercanes". These violent storms feature high winds (near the speed of sound) and enormous vortecies. Conditions of this strength would be capable of demolishing forests and other ecosystems (Lomb, 1999). Although not impossible, this theory has little supporting evidence. **Image courtesy of  Star Dust**

Supernova Explosion:

As a relatively new suggestion, this theory does not have much evidence either for or against it. It is a possibility, but more information is needed to determine its probablility. ** Graphic from  Global Change class website**

Sea -level changes and Contental Drift:

Around the time of the Permian Extinction, the continents joined to form the  super-continent Pangea and the super-ocean Panthalassa. This would radically decrease the range of shallow aquatic environments and put unnecessary stress on others. Several marine ecosystems would not be able to survive such drastic changes; their members would subsequently perish (Wingall 1996). Decrease in sea level is brought about by evaporation, glaciation, or shifts in topograhpy (Gall 1998). Warm, shallow aquatic ecosystems are very susceptible to even the slightest changes in sea level (BBC 1999). As with the formation of Pangea, few organisms could have thrived in a drasticaly changing envirnonment.

In addition to decreasing sea levels, the formation of a super continent would undoubtedly disrupt oceanic circulation. The waters would stagnate (causing a decrease in the flow of nutrients) and weather patterns would be adversely affected. Both of these changes would disrupt or destroy shallow, marine habitats .

The destruction of terrestrial life and the sudden nature of this event weaken both of these arguments. Since both aquatic and land-dwelling organisms suffered similar destruction rates (Kozur 1998), the Permian extinction must have a global cause. Also, very gradual changes, such as continental drift, could not have cause such a rapid decrease in biodiversity (Bowring 1998). These may have contributed to the overall effect, but certainly were not the sole explanation.

Volcanic activity:

Concentration of CO2 and Anoxia:

Because volcanic activiy affects the concentration of atmospheric gasses, it indirectely effects the concentration of oceanic dissolved gasses. Increases in carbon dioxide concentration aid the green house effect, and cause global warming. Scientists believe that this warming lessened the temperature gradient between the equator and the poles. As a result, thermo-haline circulation would slow and eventually stop (Wingnall 1996). The oceans would stagnate, and nutrients would fail to disperse themselves. Many marine ecosystems rely on upwelling and circulation of nutrients, oxygen included. Without the regular circulation, organisms would starve and/or suffocate (Monastersky 1996).

Conclusion:

The truth probaly includes several of these hypotheses. Never before and never since has the earth seen such widespread extinction. As Michael Lomb said on the first page of his 1999 essay, "The Permain Extinction, Earth's Greatest Catastrophe", "It's not easy to destroy most of life on Earth." Whatever caused this extinction was a mighty force. It's unlikely that any of these thoeries alone caused the Permian Extinction. Undoubtedly, many factors contributed to the die - off of so many of earth's spieces. In all probablility, volcanic activity and climate - induced changes in the oceans added to the severity of the event. Perhaps contental drift and slower global cycles laid the groundwork for this catastrophe. As of today, nobody knows the precise cause of the Permian Extinction, but the "Murder on the Orient Express" theory, proposed by Douglas Erwin in 1993, is most likely correct. It states that everything in the earth is inter -related, and as such, many factors influence each other. Changes as drastic as the Permian extinction are the product of many forces, which together cause widespread disruption. Research still continues on this topic, and our knowledge is expanding. Perhaps future discoveries will reveal the answer.

Summary of Extinction Events:

The Permian Period, which directely proceeded the Triassic, lasted from approximately 286 million years ago (mya) to 248 mya (Gall 1998). Analyzation of Uranium and Lead deposits in sediments of this time has placed the Permian - Triassic Boundry (PTB) at 250 to 251mya. This period ended with the mass extinction of the majority of life on the planet. Originally, scientists believed this was a gradual die-off, which took place over several million years. Now, due to geochronology, it was proven to have lasted less than one million years (from 252.3mya to 251.4mya +/- 300 000 years) (Bowring 1998). In such a short period of time (geologically speaking), about 85% of all marine species and 70% of all terrestrial species went extinct (Kozur, 1998). This catastrophe affected all regions equally. In opposition to popular belief, all organisms, regardless of habitat, suffered similar rates of extinction (Curran 1997). Such equality suggests that the cause of the event was a global, not local, occurrence.

Although several theories have been suggested, some are more accurate than others. We do not know the true cause of this extinction, but we can rule out some of these ideas. Because the extinction only lasted for approximately one million years and affected both terrestrial and marine habitats equally, gradual changes, as well as purely marine explanations, are unlikely answers to the problem. They may have contributed to the overall effect, but they cannot be the sole source of the crisis (Bowring 1998). Because of the sheer magnitude of this extinction event, many different factors probably contributed to its occurrence. **Graphic from  Global Change class website**

Geological epoch time spiral