Cretaceous Paleogene Extinction Event History Essay

The Cretaceous-Paleogene extinction event ( Or K-T extinction event ) marks the beginning of the Paleogene period. It besides marks the terminal of the Mesozoic Era and the start of the Cenozoic Era. Scientists believe that this event had monolithic star-shaped impacts or increased vent activity. Very late ( March 4, 2010 ) , 41 scientists from about 30 establishments have agreed that the Chicxulub asteroid had triggered this mass extinction. The asteroid was 180 kilometers in diameter, and it is the largest asteroid that has struck the Earth. Although the Earth is of class much larger than the asteroid, it had spread wildfires due to the highly hot temperature of the asteroid. Enormous daze moving ridges have generated many planetary temblors and volcanic eruptions. The emanation of dust covered the full face of the Earth, and created an highly rough environment to last in. The dust atoms besides blocked sunshine from making the surface, interrupting the growing of workss. Since workss can non photosynthesize, they die, disrupting the nutrient concatenation. Most the big animate beings have died ( Such as the dinosaurs, big birds ) due to the conditions and fortunately, the little animate beings have survived because they were able to populate in aquatic environments ( Turtles ) or were able to tunnel themselves to safety to protect themselves from the cruel environment ( Rats ) . Scientists have thought that some animate being ‘s progeny were dwarfed due to the heat and radiation.


The Paleocene is the first era in Paleogene. It lasted from about 66.4 to 56 million old ages ago. The Paleocene is instantly followed by the K-T extinction event, which killed off all the dinosaurs, some vegetations and animate beings. The name Paleocene comes from the Grecian significance “ ancient recent life. ”

The motion of the continents continues from where the late Cretaceous period has left off. Asia, Europe and North America were joined in one Northern “ Supercontinent, ” called Laurasia. Over in the Southern Hemisphere, Gondwanaland, another “ Supercontinent ” made up of Africa, South America, Austrailia and Antartica continues to divide apart. Africa heads towards Europe, and India caputs to Asia.

This Epoch was a clip where tropical and deciduous woods covered most of the land multitudes. Even the polar parts were ice-free and covered with trees! Plant population thrived and insects helped pollenate them. Temperatures are really warm and have continued to be warm throughout the Epoch. Most countries such as the Northern Hemisphere parts had a tropical, rainforest feel to it. The equator country nevertheless was hot and dry.

The tropical woods were great environments for little animate beings. On land, the mammals that filled in the functions of the dinosaurs were puny ( compared to the dinosaurs ) . Even a little modern bear is bigger than any Paleocene mammal. All these mammals are short-legged, have 5 toes on each pes and walks on the colloidal suspensions of their pess. One prevailing mammal of the period was the meat-eating Dissacus. Surprisingly, this prairie wolf sized mammal is hereditary to the giants. Most mammals from Paleocene developed in northern Asia and migrated into other parts of the universe. Gondawanaland ( Africa + South America, etc ) nevertheless, does non hold as many animate beings populating in at that place. During the late Paleocene, elephantine flightless birds of quarry appear all of a sudden in Laurasia. These large-beaked birds were the biggest and most aggressive animate beings on land for more than five million old ages.


Around 55.8 million old ages ago, there was a immense climatic perturbation in all of the Cenozoic Era. There was an unexpected planetary heating event, and temperatures spiked up to the “ Paleocene-Eocene Thermal Maximum ” . Carbon dioxide concentrations rose by a big sum. Some marine animate beings have died because of a deficiency of O ( Call anoxia ) . During the thermic upper limit, which lasted 20000 old ages, 1500 to 2000 gigatons of C were released into the ocean and atmosphere. Because of this ( And how there was circulation between the Pacific and Atlantic oceans ) , the whole universe was free of ice sheets. Over the 20000 old ages, the mean planetary temperature had increased by around 6 grades Celsius. Circulation had went wholly incorrect ; global-scale current waies and changed. For illustration, deep H2O in the Atlantic had flowed south to south during the Paleocene-Eocene Thermal Maximum alternatively of south to north. This sort of a alteration would transport warm H2O in to the deep oceans, which is why some deep sea animate beings have become nonextant.


The Eocene Epoch starts from 56 to 34 million old ages ago and is the 2nd of the three Epochs of the Paleogene clip period. The name Eocene comes from the Grecian significance “ Dawn of new mammalian animate beings. ”

Laurasia continued to interrupt isolated towards where the continents are today. Europe, Greenland and North America had drifted off from each other. In Gondwanaland, India separates from Africa and collides with Asia, organizing the Himalayan Mountains and Australia breaks off of Antarctica. In the beginning of the period when Australia and Antarctica remained connected, the warm currents of the equator part mixed with the colder Antarctic Waterss to maintain the planetary temperature heater. However, Australia had eventually split from Antarctica 45 million old ages ago and the currents were deflected off from the part, doing a cold transition between the two continents. The South-polar part began to stop dead due to the warp at the close terminal of the Epoch.

In the start of the Eocene, the warm oceans and high temperatures formed a moist environment. Forests were distributing throughout the whole Earth and most land was wholly covered in woods. Palm trees were turning all over Alaska and northern Europe, but became less plentiful as the clime cooled ( which began in the center of the Epoch ) . As Earth started to chill, it became less damp and woods started to decease out. In the terminal, North America, Eurasia ( Europe and Asia ) and the Arctic were covered in deciduous trees while the southern parts were covered in rain forests ( they were closer to the equator, and had much warmer temperatures than the northern country ) . Antarctica on the other manus became much colder and the full vegetation there was wiped out.

The animate beings continued to germinate and became more diverse. Animals with hooves ( odd-toed ungulate ) , even toed ( even-toed ungulate ) and primates began to look. Some of them had long and thin legs, and some with pess and custodies that are capable for hold oning. Many or all of these animate beings were little ( even smaller than the Paleocene zoology! ) , but continue to turn larger in size. Titanotheres ( similar to Rhinoceroses ) rapidly grew to a immense size, but have died out due to a mass extinction at the terminal of the Eocene. New aquatic mammals have besides appeared in the oceans. Giants and sea cattles of today had come from the Archaeoceti ( A land animate being that became more aquatic, similar to the Dissacus ) and the Basilosaurus ( A really long shark/whale like animal ) . When Africa was separated by the ocean on all sides, it allowed the development of alone zoologies due to the acquired traits an carnal gets and base on ballss on due to the environment it is stuck in. South America besides became an stray continent and it became a topographic point for hoofed animate beings and elephantine flightless birds. Sadly, there was another extinction event that marks the terminal of the Eocene and the start of the Oligocene. Numerous animate beings such as Basilosaurus became nonextant. It was believed that meteorite impacts, clime alteration ( acquiring colder ) and increased vent activity caused a batch of animate beings to go nonextant or in danger.


The Oligocene is the last Epoch of the Paleogene period and starts from around 34 to 23 million old ages ago. In Greek, Oligocene means “ few and new, ” and it refers to how scarce the diverseness of the zoology is compared to the effusion of new animate beings in the Eocene.

The temperatures during the Oligocene were get downing to acquire ice chest. Antarctica nevertheless, formed glaciers for the first clip in the whole Cenozoic epoch! The addition of ice sheets led to a autumn in sea degree. The cool temperatures have wiped out even more tropical woods and deciduous woods replace them.

During this era, the continents still float toward their locations today. Antarctica became more stray down the south and developed a lasting ice cap, pass overing out all the animate beings that ca n’t defy cold temperatures, and the full vegetation. Africa and Europe combined, and eventually shuting Tethys Sea ( The sea at the centre of the Earth between Europe and Central Asia ) . South America had besides split away of Antarctica and impetuss towards North America. Australia and South America were isolated from any other land multitudes during this Epoch.

Angiosperms ( blooming workss ) have expanded throughout the whole universe ( except Antarctica ) . All the tropical woods were limited to merely the equatorial country ; South America, Africa and Australia were merely covered in tropical woods. North America was a sub tropical country. Deciduous, litchi and Anacardium occidentale trees have dominated and the pea and bean household had spread. Colder countries of the universe contained fields instead than woods.

Isolated continents like South America, Africa and Australia contained their ain alone zoology. Because there was a batch of unfastened fields and free infinite, animate beings were able to turn to larger sizes. Animals like Equus caballuss, rhinoceroses and oreodonts ( Hippo like animate being ) adapted to the fields as rain forests started to decease out in the non equatorial parts. South America had distinct fauna because it was isolated and it was home to unusual animate beings such as pyrotheres ( Medium sized tusked animate beings like mammoths with hooves/paws ) , and astrapotheriae ( hoofed animate being that resembles a really smell gigantic animal, approximately 3 metres long ) . Marine animate beings of Oligocene resembled today ‘s aquatic animals. Giants continue to germinate from Archaeocetes ( The terrain, coyote like animate being that adapted to the aquatic life ) . Pinniped mammals appeared near the terminal of the era, and are related to bears and otters.