Megafaunal Loss by Mark Valentine

Hello again. Like I said before, I’m Mark Valentine and I’m going to be talking about Megafaunal Extinction and how it affects present and future biodiversity. Before I begin, you probably are going to want to know what exactly Megafauna are. Megafauna are HUGE animals. This would certainly include animals like elephants and giraffes, but also lions, tigers and bears. All these animals, however, are relatively well known and still exist in the world today. What many people don’t know is that there were many incredible Megafauna that existed a few thousand years ago that are now extinct. Around 50,000 years ago, at the end of the last Ice Age, Megafauna worldwide underwent massive and widespread extinctions . Before then, there were all kinds of amazing and enormous animals worldwide: In Eurasia, there were wooly mammoths and saber tooth cats, which you’ve probably heard of, but in North America there were beavers the size of small cars and 9 foot tall Bison with horns that spanned over 6 feet , in South America there were 5 foot tall armadillos and Giant Ground Sloths the size of elephants , and in Australia there were wombats the size of Hippopotamuses . All these animals have two things in common: One, that they are absolutely massive, and two, that they have all contributed to the historical phenomenon that Megafauna are more likely to go extinct than smaller animals . So what caused these extinctions? There are two causes. We know that human hunting lead to the extinction of many Megafaunal species, like Steller’s Sea Cow, which was basically a 30 feet long , 20,000 pound manatee . Another major cause of these extinctions was climate change. A recent study showed that climate change had significant effect on many species, and actually may have been the cause of extinction for wooly rhinos, giant bison, and other Megafauna . So what does this mean for present and future biodiversity? It’s not good. The same two factors—humans and climate—are again playing a role in Megafaunal extinctions. As humans increase in population and expand outwards, more and more animals are being threatened, and since Megafauna need more living space than other animals they are more affected. Animals including pandas and tigers are already endangered because of this. We’re also experiencing global climate shifts due to global warming, which is already causing a decline in Megafauna like the polar bear . The continued global trend of a loss of large animals is clearly leading towards one result: a world overrun with the smallest kinds of animals which can live alongside humans, or in other words, a world overrun with rodents . But this does not have to happen. If we as humans can dramatically change the way we live to reduce climate change and preserve wildlife, we can maintain biodiversity, especially among Megafauna, for much longer. The only question is, can we change? ``` Wikipedia contributors. "Quaternary extinction event." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 20 Nov. 2011. Web. 30 Nov. 2011. Kurtén, B. and E. Anderson (1980). Pleistocene Mammals of North America. Columbia University Press. pp. 236–237. ISBN 0231037333. Wikipedia contributors. "Bison latifrons." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 13 Nov. 2011. Web. 30 Nov. 2011. Wikipedia contributors. "Doedicurus." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 16 Jun. 2011. Web. 30 Nov. 2011. Wikipedia contributors. "Megatherium." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 10 Oct. 2011. Web. 30 Nov. 2011. Wikipedia contributors. "Diprotodon." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 26 Nov. 2011. Web. 30 Nov. 2011. Turvey S. T., Fritz S. A. 2011 The ghosts of mammals past: biological and geographical patterns of global mammalian extinction across the Holocene. Phil. Trans. R. Soc. B 366, 2564–2576. Sally M. Walker (1999). Manat