Donald Frederick of the 'National Geographic' reported some 11 fossils of lizard-like creatures called cynodonts from the Triassoc Period were located in the Northern Hemisphere back in 1990. The mammal-like reptiles were said to have symbolized "a planet in transition that would change dramatically in the next few million years." 

At the time "the emerging true mammals would become bit players, relegated to the sides as the dinosaurs took center stage." According to extinction theorist David Jablonski, "Mass extinctions change the rules of evolution. When one strikes, it's not necessarily the most fit that survives; often it's the most fortunate." It was understood, "Drastic changes in the environment can suddenly put healthy species at a disadvantage. Others that have barely been hanging on can squeak through and inherit the Earth." And those others were mammals. 

Dinosaurs and mammals were said to have originated within 10 million years of each other about 220 million years ago. However while the dinosaurs ruled the planet for 140 million years, mammals remained a minority. Then another "mass extinction" saw the dinosaurs wiped out about 65 million years ago. It was then mammals became a majority. Within 10 million years, "there were mammals of all shapes and lifestyles: whales and bats, carnivores and grazers." In hindsight, "mammals just couldn't do anything interesting until the dinosaurs were out of the way." 

Although man was said to have descended from creatures that lived in the sea over 2000 million years ago, none of the oceans in 1972 which previously inhabited by his ancestors had endured. This was "after mammals began to evolve from certain reptilian species around 220 million years ago." Back in 1935, scientist Columbus Iselin from the Oceanographic Institution told the Associated Press, "We want to determine whether the living processes of the animals affect the water or whether the water affects the animals. You know, there is very little oxygen at a depth of about 900 meters." 

The Age of Reptiles took place some 225 million years ago. It was during the Palaeozoic ('ancient life') Era when "plants and animals conquered the land and large amphibians and reptiles evolved." The last 600 million years of Earth’s existence were said to have split up into 3 big eras: (1) the Palaeozoic (ancient life) Era, (2) the Mesozoic (middle life) Era and (3) the Cainozoic (new life) Era. In the Triassic Period a new era emerged, which became known as the Mesozoic Era. The Age of Dinosaurs was part of the Mesozoic Era which included the 3 geological periods: the Triassic, the Jurassic and the Cretaceous.  

During the Triassic Period (roughly between 225 and 193 million years ago), the continents were said "locked together, forming one great world-continent." The center was mainly desert and mostly hot. A variety of amphibians and reptiles could be found. On land, mammal-like reptiles were at first the majority. However by the end of the period they were replaced by the first dinosaurs, ranging from small, lightly built animals like Coelophysis to the heavy Plateosaurus. Some of the mammal-like reptiles would eventually evolve into the first true mammals. 

During the Jurassic Period (roughly between 193 and 136 million years ago), the changes around the world in geographical conditions and climate paralleled the changes in animal life. "A new burst of evolution among reptiles establishes the dinosaurs as rulers of the land." However "the world-continent" began to break up: the northern group of continents started to separate from the southern. The seas advanced inland covering much of Europe and Asia. The climate was milder and slightly humid, and desert areas shrunk in size. At the time there was sufficient rain to support "luxuriant vegetation." Dinosaurs diversified and gained in size until they dominated the land. 

During the Cretaceous Period (roughly between 136 and 65 million years ago), "modern types of plants and animals appear, foreshadowing the end of the Mesozoic Era and the dawn of the Cainozoic, the era of modern life." At the end of the period the dinosaurs would die out bringing an end to the the Age of Reptiles. At the time the modern continents started to form and warm, shallow seas advanced further inland. North America and Africa were united. South Atlantic would expand into a major ocean. As noted, "Mountain-building in the second half of the period begins to form the Alps, Andes, Himalayas and Rockies." Dinosaurs still ruled the land but were gradually challenged by new types of small mammal. 

Charles Darwin maintained "all forms of life evolved from a common ancestor. Genetic analysis, for example, has shown that every organism is governed by the same genetic code controlling the same kind biochemical processes. Exactly how evolution happened is now a matter of great controversy among biologists," the New York Times reported in 1980. That year, in October, some 150 scientists specialized in evolutionary studies would convene for 4 days at the Field Museum of Natural History in Chicago to get "a much deeper understanding of the evolutionary history of life on Earth." At issue was macroevolution or "the evolution of major differences, such as those separating species or larger classifications."

In April 1934, Professor Conklin from Princeton told the American Philosophical Society, it would seem to be that higher temperature would build up the variation of species and probably the speed of evolution. He based this theory from breeding fruit flies. It was noted there was a general decline of evolution during the Proterozoic Era (around 600 million years ago) and "almost no change occurred for ages in the worms and seaweeds which then were the most numerous and probably the highest forms of life. Then suddenly came evolution's first great spasm of activity. The opening of the immediately subsequent Paleozoic Era found already established in the sea recognizable predecessors of all the greater groups of creatures without backbones." 

It was believed a second similar "explosion of the evolutionary urge" during the Age of Reptiles, "when Nature contrived the most bizarre and extreme varieties of land animals which ever lived." A third "explosion of the evolutionary urge" was also believed not long before the Ice Age; "one which perhaps found one of its results in man."

Based on rock records, "there have been times in past Earth history when warmth weather was greater than the present day, as well as other times when much of the world was colder." But there was no proof that the periods of climatic warmth and of rapid evolution were the same. Changes in solar (previously also called 'terrestrial radioactivity'), changes from age to age in the intensity of the cosmic rays and man other ideas gave as reasons the "causes of the successive evolutionary explosions".

It was pointed out, "many creatures which have survived from ancient ages almost unchanged, although they were immune to evolution, are dwellers in cold environments; such as the lingual shellfish inhabiting moderately deep ocean waters or the common cockroach which seeks damp and cool spots underneath forest debris."

Blog Archive