In this, our final post, we will recap every part of our investigation and then provide a final analysis. The first topic we talked about was the climate. There we talked about each epoch's cliamte. We began with the Miocene which was a time of warmer global climates than those in the preceding Oligocene. During this time modern patterns of atmospheric and ocean circulation formed. Then came the Pliocene, where we saw the continuation of the climatic cooling that had began in the Miocene, with the beginning of the large ice caps, especially in Antarctica, and the northern hemisphere lands and ocean cooling as-well. This was followed by the Pleistocene were, about a third of the way into the epoch, the the first Ice Age hit. There were a series of advances and retreats of the ice, as the climate fluctuated between cold and warm periods. Our final Epoch, the Holocene, where we saw minor geographic shifts in the Holocene, but very large climatic shifts. Ice core records show that before the Holocene there were global warming and cooling periods, but climate changes became more regional.
Then we talked about the geography of the time. The Neogene Period was a time when the continents were crashing into each other. Mountains pushed up in many places. Sea levels were lower due to the effects of continental collision. The North and South Poles began to have ice caps. During the Neogene Period, the polar ice thickened and took up more space in the ocean. This drop in sea levels opened up land bridges between continents, which enabled the migration of animals between them.
Our third topic was that of the plant and animal life of the Neogene. Under the triple hammers of drought, starvation and cold, herbivorous species were smashed or utterly changed. Their predators followed them into extinction or transformation. The later Neogene saw the creation of an entirely new guild of hunters, the pursuit predator, able to follow scarce prey across miles of open country rather than waiting for the easier opportunity which might never come. The pursued developed their own responses: herd behaviors, seasonal migrations, and big bodies, adapted for speed and endurance. In water, sharks grew and dominated the seas once again. Megalodon, the biggest shark of all. On land, hominins split from their closest African ape ancestors, the chimpanzees. Adapted to two-footed walking, early hominins dropped out of the trees and started to carry food and tools in their hands. These new species were poised to alter the planet unlike any other in the centuries to come.
As for the vegetation, two major ecosystems first appeared during the Miocene: kelp forests and grasslands. The expansion of grasslands is correlated to a drying of continental interiors and a global cooling. Later in the Miocene a distinct cooling of the climate resulted in the further reduction of both tropical and conifer forests, and the flourishing of grasslands and savanna in their stead.
Finalizing our investigation,The Neogene encompasses four epochs, beginning with the Miocene (23.03-5.33 Mya), followed by the Pliocene (5.33-1.806 Mya), the Pleistocene (the "Ice age", 1.806-0.0115 Mya) and the current epoch, the Holocene, beginning eleven thousand five hundred years ago. Whales diversified in the seas, and sharks reached their largest size during the Miocene. Complex patterns of mammalian evolution resulted from changing climates and continental separations. More modern mammals evolved amazing Eras of history.
sábado, 4 de octubre de 2008
This a continuation of our previous post, with the exception that we will not focus on animals but instead on the Neogene Era's vegetation. Two major ecosystems first appeared during the Miocene: kelp forests and grasslands. The expansion of grasslands is correlated to a drying of continental interiors and a global cooling. Later in the Miocene a distinct cooling of the climate resulted in the further reduction of both tropical and conifer forests, and the flourishing of grasslands and savanna in their stead.The fauna of the Pliocene does not differ much from that of the Miocene, although the period is regarded by many zoologists as the climax of the Age of Mammals. This epoch is characterized by the appearance of all of the presently existing orders and families, and many of the existing genera of mammals. Pliocene Vegetation was very like today's. Grasslands replaced forests, so grazing mammals spread at the expense of browsers. As we can see, this period is mostly marked by the appearance of grasslands.
viernes, 3 de octubre de 2008
This post will be completly dedicated to the Vegetation and Animal Life of the Neogene Era. As we explained in our last post, grasses appeared at the beginning of the Miocene and quickly replaced the thinning forests. But grasses are poor fodder: tough, low in nutrients, high in tooth-destroying silicates. They die back to their roots in cold weather. Under the triple hammers of drought, starvation and cold, herbivorous species were smashed or utterly changed. Their predators followed them into extinction or transformation. The later Neogene saw the creation of an entirely new guild of hunters, the pursuit predator, able to follow scarce prey across miles of open country rather than waiting for the easier opportunity which might never come. The pursued developed their own responses: herd behaviors, seasonal migrations, and big bodies, adapted for speed and endurance.
Another line of adaptation led to small-bodied generalists -- rodents, raccoons, rabbits, and possums -- and their predators, the foxes, cats, dogs and snakes. These generalists were mainly unspecialized herbivores or omnivores, with partially fossorial habits, strong territoriality and high reproductive rates. Theirs was the ability to exploit many resources within small, locally or temporarily favorable conditions, excluding competition and using rapid reproduction as a defense to predation, to quickly take new territory, or to recover from local disasters. These organisms often developed seasonal torpor as a method for surviving seasonal extremes.
A few species do not fall neatly into any of these categories. Humans are one. Bears are another. In one sense, these are hyper-generalists, able to use a wide repertoire of behavioral adaptations to compensate for a conspicuous absence of genetically-endowed talents. In another sense, they are throw-backs to a style of life more common in the Paleogene or the Late Mesozoic. The survival of this group is hard to explain, with so many other, robust lineages disappearing. The continental connections gave animals that had evolved in isolation access to new lands. Elephants and apes wandered from Africa to Eurasia. Rabbits, pigs, saber-toothed cats, and rhinos went to Africa. Elephants and rhinos continued across the Bering Strait to North America. Horses went the other way. Ground sloths migrated from South America to North America; raccoons scurried south. Even rodents may have hopped Pacific islands en route to Australia from Southeast Asia.
Horses evolved stronger, enamel-protected teeth and flourished. So too did ruminants such as bison, camels, sheep, and giraffes, whose compartmentalized stomachs are well adapted to digesting grass. Many of the grazers were quick and roamed in herds—new tricks for survival out in the open. Their predators were also forced to adapt.
In the oceans, a new type of large brown algae, called kelp, latched onto rocks and corals in cool shallow waters, establishing a new habitat favored by sea otters and dugongs, a marine mammal related to the elephant. Sharks grew and dominated the seas once again. Megalodon, the biggest shark of all, was nearly 50 feet (15 meters) long.
On land, Asian and African apes diverged and then, several million years later, hominins split from their closest African ape ancestors, the chimpanzees. Adapted to two-footed walking, early hominins dropped out of the trees and started to carry food and tools in their hands. These new species were poised to alter the planet unlike any other in the centuries to come.
Another line of adaptation led to small-bodied generalists -- rodents, raccoons, rabbits, and possums -- and their predators, the foxes, cats, dogs and snakes. These generalists were mainly unspecialized herbivores or omnivores, with partially fossorial habits, strong territoriality and high reproductive rates. Theirs was the ability to exploit many resources within small, locally or temporarily favorable conditions, excluding competition and using rapid reproduction as a defense to predation, to quickly take new territory, or to recover from local disasters. These organisms often developed seasonal torpor as a method for surviving seasonal extremes.
A few species do not fall neatly into any of these categories. Humans are one. Bears are another. In one sense, these are hyper-generalists, able to use a wide repertoire of behavioral adaptations to compensate for a conspicuous absence of genetically-endowed talents. In another sense, they are throw-backs to a style of life more common in the Paleogene or the Late Mesozoic. The survival of this group is hard to explain, with so many other, robust lineages disappearing. The continental connections gave animals that had evolved in isolation access to new lands. Elephants and apes wandered from Africa to Eurasia. Rabbits, pigs, saber-toothed cats, and rhinos went to Africa. Elephants and rhinos continued across the Bering Strait to North America. Horses went the other way. Ground sloths migrated from South America to North America; raccoons scurried south. Even rodents may have hopped Pacific islands en route to Australia from Southeast Asia.
Horses evolved stronger, enamel-protected teeth and flourished. So too did ruminants such as bison, camels, sheep, and giraffes, whose compartmentalized stomachs are well adapted to digesting grass. Many of the grazers were quick and roamed in herds—new tricks for survival out in the open. Their predators were also forced to adapt.
In the oceans, a new type of large brown algae, called kelp, latched onto rocks and corals in cool shallow waters, establishing a new habitat favored by sea otters and dugongs, a marine mammal related to the elephant. Sharks grew and dominated the seas once again. Megalodon, the biggest shark of all, was nearly 50 feet (15 meters) long.
On land, Asian and African apes diverged and then, several million years later, hominins split from their closest African ape ancestors, the chimpanzees. Adapted to two-footed walking, early hominins dropped out of the trees and started to carry food and tools in their hands. These new species were poised to alter the planet unlike any other in the centuries to come.
In this post, we will talk about the geography of the Neogene Period. The Neogene Period was a time when the continents were crashing into each other. Mountains pushed up in many places. India continued its push into Asia. This created the Himalayan Mountain Range. Italy moved north into Europe raising the Alps. Spain crashed into France to form the Pyrenees. The Rocky Mountains and the Andes Mountains formed in North and South America during this time. Sea levels were lower due to the effects of continental collision. The North and South Poles began to have ice caps. During the Neogene Period, the polar ice thickened and took up more space in the ocean. The new mountains trapped water as snow and ice. All of this ice formation caused sea levels to drop even more. The drop in sea levels opened up land bridges between continents. This allowed animals to migrate between continents. South America moved to the north. By the Pliocene Epoch it merged with North America forming the Isthmus of Panama. This caused armadillos, porcupines, ground sloths and opossums to migrate from South America to North America and Dogs, cats, bears, and horses from North America crossed into South America.
As we stated in our previous post, the climate continued to cool. Many of the areas that had been covered by forests were changing to grasslands. Grasses were better suited to the cool dry weather. But grasses had less nutrition than the forest plants of the Paleogene Period. It took more effort to get the nutrients out. Grasses were made of chemicals that were hard on teeth. Chewing wore the teeth down. Animals that ate grasses needed stronger teeth. Changes in the plants meant that the animals had to adapt or die. Many of the forest dwellers became extinct and new animals developed that could live on the grasses. Horses had long, flat-topped teeth that were especially good at grinding the grasses. Their teeth grew longer and kept pushing up through their gums to keep up with the wear that came from chewing.
Other animals developed new ways to digest the grasses inside their bodies. These animals had more than one stomach. They are called ruminants. They were efficient at getting nutrients from the grasses. This new type of animal, the artiodactyl, developed into many familiar species: camels, bison, sheep and giraffes.
As we stated in our previous post, the climate continued to cool. Many of the areas that had been covered by forests were changing to grasslands. Grasses were better suited to the cool dry weather. But grasses had less nutrition than the forest plants of the Paleogene Period. It took more effort to get the nutrients out. Grasses were made of chemicals that were hard on teeth. Chewing wore the teeth down. Animals that ate grasses needed stronger teeth. Changes in the plants meant that the animals had to adapt or die. Many of the forest dwellers became extinct and new animals developed that could live on the grasses. Horses had long, flat-topped teeth that were especially good at grinding the grasses. Their teeth grew longer and kept pushing up through their gums to keep up with the wear that came from chewing.
Other animals developed new ways to digest the grasses inside their bodies. These animals had more than one stomach. They are called ruminants. They were efficient at getting nutrients from the grasses. This new type of animal, the artiodactyl, developed into many familiar species: camels, bison, sheep and giraffes.
Suscribirse a:
Entradas (Atom)
The Neogene
The Present
