首页
登录
职称英语
Generally, in order to be preserved in the fossil record, organisms must
Generally, in order to be preserved in the fossil record, organisms must
游客
2025-02-09
36
管理
问题
Generally, in order to be preserved in the fossil record, organisms must possess hard body parts
such as shells or bones. Soft, fleshy structures are quickly destroyed by predators pr decayed by
bacteria. Even hard parts left on the surface for and length of time will be destroyed Therefore,
organisms must be buried rapidly to escape destruction by the elements and to be protected
(5) agents of weathering and erosion Marine organisms thus are better candidates for
fossilization than those living on the land because the ocean is typically the site of sedimentation,
whereas the land is largely the site of erosion.
The beds of ancient lakes were also excellent sites for rapid burial of skeletal remains of
freshwater organisms and skeletons of other animals, including those of early humans Ancient
(10) swamps were particularly plentiful with prolific growths of vegetation, which fossilized in
abundance. Many animals became trapped in bogs overgrown by vegetation. The environment of
the swamps kept bacterial decay to a minimum, which greatly (aide(D)in the preservation of plants
and animals. The rapidly accumulating sediments in flood plains, deltas, and stream channels
buried freshwater organisms, along with other plants and animals that happened to fall into the
(15) water.
Only a small fraction of all the organisms that have ever lived are preserved as fossils. Normally,
the remains of a plant or animal are completely destroyed through predation and decay. Although
it seems that fossilization is common for some organisms, for others it is almost impossible. For
the most part, the remains of organisms are recycled in the earth, which is fortunate because
(20) otherwise soil and water would soon become depieted of essential nutrients. Also, most of the
fossils exposed on Earth’s surface are destroyed by weathering processes. This makes for an
incomplete fossil record with poor or no representation of certain species.
The best fossils are those composed of unaltered remains. Generally, it is the inorganic hard parts,
composed mostly of calcium carbonate, that form the vast majority of unaltered fossils. Calcite and
(25) aragonite also contributed to a substantial number of fossils of certain organisms.
选项
A、is not likely to appear in the fossil record
B、is not heavy enough to sink below the surface
C、is not attractive to predators
D、takes a long time to decay
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3949737.html
相关试题推荐
Generally,inordertobepreservedinthefossilrecord,organismsmust
Palcontologists(haveexamined)fossilembryosandhatchlings(from)three(type
(Fossil)recordssupporttheassumption(which)microorganisms(were)thefirst
(Amost)usefultool(foranalyzing)theelemental(compositionoffossils)ist
→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange
→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange
→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange
→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange
→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange
→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange
随机试题
Thatbringsmetomyfinalpoint,whichishowdowehelpgivetheClimateG
MoreandmoreAmericansarereadingtheirowncreditreport.Creditreportsare
Whatpreventsthemanfromtakingthepoetsof1960sclass?[br][originaltext]
在数字内容产品中,关于内容要素的加工,下列说法正确的是( )。A.上角标和下角
竖曲线的要素有()。A.交叉点 B.转折角 C.半径 D.切线长 E.
女性,50岁。间断上腹部隐痛10年余,冬春季节较明显,近半年自觉上腹疼痛加重,伴
全脂奶粉调制成乳汁,奶粉与水的体积比应为A.1:10 B.1:1 C.1:4
KIA不能观察到的是A.葡萄糖发酵B.乳糖发酵C.HS产生D.动力E.有无产气
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
浮萍具有的功效是A.透疹止痒 B.除烦止渴 C.和胃化湿 D.宣肺平喘
最新回复
(
0
)