Tuesday, May 17, 2016

Quaternary extinction event

I was thinking if humans could experience a Quaternary extinction event. Outside of an asteroid or planet hitting the earth like 65 million years ago maybe not. But, I was thinking if a plague that got 94% dead hit at the same time as an ice age hit that might extinct the human race too.  


begin quote from:

https://en.wikipedia.org/wiki/Quaternary_extinction_event

 

Quaternary extinction event

From Wikipedia, the free encyclopedia
Late Pleistocene landscape of northern Spain (left to right- Equus ferus, Mammuthus primigenius, Rangifer tarandus, Panthera leo spelaea, Coelodonta antiquitatis)
The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. However, this extinction wave did not stop at the end of the Pleistocene, but continued, especially on isolated islands, in human-caused extinctions, although there is debate as to whether these should be considered separate events or part of the same event.[1] Among the main causes hypothesized by paleontologists are natural climate change and overkill by humans,[2] who appeared during the Middle Pleistocene and migrated to many regions of the world during the Late Pleistocene and Holocene. A variant of the latter possibility is the second-order predation hypothesis, which focuses more on the indirect damage caused by overcompetition with nonhuman predators. The spread of disease is also discussed as a possible reason.

Contents

The Pleistocene or Ice Age extinction event

The Late Pleistocene extinction event saw the extinction of many mammals weighing more than 40 kg.
The extinctions in the Americas entailed the elimination of all the larger (over 100 kg) mammalian species of South American origin, including those that had migrated north in the Great American Interchange. Only in North America, South America, and Australia, did the extinction occur at family taxonomic levels or higher.
There are three main hypotheses concerning the Pleistocene extinction:
  • The animals died off due to climate change associated with the advance and retreat of major ice caps or ice sheets.
  • The animals were exterminated by humans: the "prehistoric overkill hypothesis" (Martin, 1967).[3]
  • The extinction of the woolly mammoth (by whatever cause, perhaps by humans) changed the extensive grasslands to birch forests, and subsequent forest fires then changed the climate.[4] We now know that immediately after the extinction of the mammoth that birch forests replaced the grasslands and that an era of significant fire began.[5]
There are some inconsistencies between the current available data and the prehistoric overkill hypothesis. For instance, there are ambiguities around the timing of sudden extinctions of Australian megafauna.[3] Biologists note that comparable extinctions have not occurred in Africa and South or Southeast Asia, where the fauna evolved with hominids. Post-glacial megafaunal extinctions in Africa have been spaced over a longer interval.
Evidence supporting the prehistoric overkill hypothesis includes the persistence of certain island megafauna for several millennia past the disappearance of their continental cousins. Ground sloths survived on the Antilles long after North and South American ground sloths were extinct. The later disappearance of the island species correlates with the later colonization of these islands by humans. Similarly, dwarf woolly mammoths died out on remote Wrangel Island 1,000 years after their extinction on the mainland. Steller's sea cows also persisted in seas off the isolated and uninhabited Commander Islands for thousands of years after they had vanished from the continental shores of the north Pacific.[6]
Alternative hypotheses to the theory of human responsibility include climate change associated with the last glacial period and the Younger Dryas event, as well as Tollmann's hypothetical bolide, which claim that the extinctions resulted from bolide impact(s). Such a scenario has been proposed as a contributing cause of the 1,300 year cold period known as the Younger Dryas stadial.[citation needed] This impact extinction hypothesis is still in debate due to the exacting field techniques required to extract minuscule particles of extra terrestrial impact markers such as Iridium at a high resolution from very thin strata in a repeatable fashion, as is necessary to conclusively distinguish the event peak from the local background level of the marker.[citation needed] The debate seems to be exacerbated by infighting between the Uniformitarianism camp and the Catastrophism camp.[citation needed]
The Chalicothere vanished in the early Pleistocene

Africa and Asia

See also: List of African animals extinct in the Holocene and List of Asian animals extinct in the Holocene
The Old World tropics have been relatively spared by Pleistocene extinctions. Africa and southern Asia are the only regions that have terrestrial mammals weighing over 1000 kg today. However, during the early, middle and late Pleistocene some large animal forms disappeared from these regions without being replaced by comparable successor species. Climate change has been cited as most likely causing the extinctions in Southeast Asia.[7]
Eucladoceros cranium fossil, Museo di Paleontologia di Firenze
Steppe Mammoth (Mammuthus trogontherii) dimensions
Megantereon restoration
A Pachycrocuta bevirostris reconstruction
The modern Jaguar (Panthera onca), although now restricted to the Americas, originated in Asia, before colonising both sides of Beringia- Europe in the form of the European jaguar, and in the Americas as the predecessors of today's species.
Australopithecus family reconstruction.
Homotherium restoration- although Homotherium were extirpated in Africa 1.5 mya, they had spread throughout Eurasia and the Americas, remaining in South America at least until the Middle Pleistocene, and perishing in all other continents during the late Pleistocene.
Pelagornis sandersi comparison with the Andean condor (Vultur gryphus) and the Wandering albatross (Diomeda exulans)
Steppe bison (Bison priscus) cave art.
Life reconstruction of the extinct Megaloceros
A woolly rhinoceros (Coelodonta antiquitatis) from a late Pleistocene landscape in northern Spain.
Painting of a Cave Lion (Panthera leo spelaea)
Megalochelys atlas reconstruction
Wall drawing in the cave Les Combarelles in Dordogne (wild horse, cave bear, mammoth, cave lion).
Megafauna that disappeared in Africa or Asia during the Pleistocene include:
Megafauna that disappeared in Africa and Asia during the Late Pleistocene:

The Pacific (Australasia and Oceania)

See also: Australian megafauna, List of extinct animals of the Hawaiian Islands, and List of extinct animals of New Zealand
Diprotodon became extinct around 50,000 years ago.
Procoptodon goliath reconstruction
Thylacoleo carnifex rock art
Megalania priscus skeleton, Melbourne Museum
Reconstruction of the Late Pleistocene mekosuchine crocodile, Mekosuchus inexpectans, of prehistoric Fiji.
Comparison of the extinct Giant Fijian Iguana, Lapitiguana impensa, and two Viti Levu Giant Pigeons, Natunaornis gigoura, from prehistoric Fiji.
In Australia, the sudden spate of extinctions occurred earlier than in the Americas. Most evidence points to the period immediately after the first arrival of humans—thought to be a little under 50,000 years ago—but scientific argument continues as to the exact date range. In the rest of the Pacific (New Guinea, New Caledonia, the rest of Australasia and Oceania) although in some respects far later, endemic fauna also usually perished quickly upon the arrival of humans in the late Pleistocene and early Holocene This section does not include any spate of extinctions post 1000 BCE (e.g. subatlantic New Zealand or Hawaii).
The extinctions in the Pacific included:
Posted by at
Labels:

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)