首页
登录
职称英语
Over a century ago, Alfred Russell Wallace wrote that "we live in a zoologic
Over a century ago, Alfred Russell Wallace wrote that "we live in a zoologic
游客
2023-08-29
34
管理
问题
Over a century ago, Alfred Russell Wallace wrote that "we live in a zoologically poor world, from which all the hugest, fiercest and strangest forms have recently disappeared. " Researchers seeking to explain this " marvelous fact", as Wallace called it, fall into two camps, one invoking global climatic change and the other human hunting as the cause.
Over the past few decades, the debate has become
deadlocked, in part because most researchers have focused their attention on the Americas and northern Eurasia, where the extinction of the huge, fierce, and strange creatures, such as mammoths, and giant sloths(大树懒), occurred between 12, 500 and about 11, 000 years ago. This was a time of rapid climatic change, but it was also when humans first arrived in these regions, making it difficult to discern causality. Australia provides the only separate, continent-sized natural laboratory in which dramatic Quaternary extinctions occurred. It is thus of exceptional importance as a testing ground for extinction theories, but until now problems with dating have limited its potential. Miller and some people have now documented the extinction of the gigantic Australian bird and so have broken new ground in dating huge creatures extinction in Australia. At the same time, these authors have broken the current deadlock in the great huge creature extinction debate.
It has long been appreciated that the intensity of Quaternary extinctions varied greatly around the world. In the oceans, Africa, and Southeast Asia, they were nonexistent or mild. Europe experienced moderate extinction rates, whereas the Americas, Australia, Madagascar, and many Oceanic islands suffered dramatic extinctions. North America lost 73% of all forms weighing more than 44 kg, but Australia suffered the most severely of all the continents, losing every terrestrial vertebrate(脊椎动物)species larger than a human, as well as many smaller mammals, reptiles, and flightless birds, the latter down to about a kilogram in weight. In all, about 60 vertebrate species were lost, including bizarre marsupials(有袋类动物)that resembled giant sloths, kangaroos, and a terrestrial horned tortoise that approached the size of a Volkswagen Beetle car. Establishing just when this bizarre array of creatures last trod Australia’s outback has been an intricate business, with many false leads and sites that are difficult to interpret.
For decades, it was believed that the huge creatures survived until close to the time of the glacial maximum, some 20, 000 years ago, when temperatures were up to 9t cooler than at present and the continent was extremely arid. Conditions were so extreme that trees virtually disappeared from the inland, and 40% of Australia was transformed into a vast active dune field. [br] Before the Quaternary extinction, there lived______whose weight was down to a kilogram in Australia.
选项
答案
many smaller mammals, reptiles and flightless birds
解析
根据线索词down to a kilogram定位在第三段第五句话上。文中说澳大利亚在第四纪灭绝时失去了很多物种,其中包括小型的体重在1千克左右的哺乳动物、爬行动物及不能飞的鸟类,由此知答案。
转载请注明原文地址:https://tihaiku.com/zcyy/2966969.html
相关试题推荐
AscivilwarseruptedthroughouttheRomanRepublicinthe1stcenturyB.C.
AscivilwarseruptedthroughouttheRomanRepublicinthe1stcenturyB.C.
AscivilwarseruptedthroughouttheRomanRepublicinthe1stcenturyB.C.
AscivilwarseruptedthroughouttheRomanRepublicinthe1stcenturyB.C.
As20thcenturyapproaches,wecanfind________________(更多女性进入电影行业).morewome
假如你是李明,写一封求职信,内容包括:1.你对8月18日在21stcentury报上所登的招聘外贸经理的广告很感兴趣。2.你是某重点大学一名四年级学生,今
Priortothe20thcentury,womeninnovelswere______(屈从于种种束缚)imposedbythemal
Anightoutattheoperatoseeanadaptationofanobscure17th-centuryEng
Anightoutattheoperatoseeanadaptationofanobscure17th-centuryEng
Overacenturyago,AlfredRussellWallacewrotethat"weliveinazoologic
随机试题
Fillalltheholeswith______firstbeforeyoupaintthewall.A、perfumeB、greas
Onaverage,Americankidsaged3to12spent29hoursaweekinschool,eigh
Doeswinningmeaneverything?Askkidsandtheanswerisprobably"No".Ask
Scandalsarerootedintest-basedsystems;theyexistwithorwithoutfraud.
如果后牙缺牙间隙垂直距离或者近远中径较小,可以考虑使用的修复失牙的方法为(
甲公司以定向增发股票的方式购买同一集团内另一企业持有的A公司80%股权。为取得该
数字中国,催动发展蝶变 垃圾分类绿色能量生成机,雕塑AR合影,云
金融市场最基本、最重要的功能是( )。A.融通货币资金 B.资源配置 C.
图8—1是资产组合价值变化△Π的概率密度函数曲线,其中阴影部分表示( )。
一般资料:求助者,男性,24岁,在读研究生。 案例介绍:求助者研究生入学后不久
最新回复
(
0
)