首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Once found almost entirely in the western United States and in As. ia, dinosaur fossils are now being discovered on all seven co
Once found almost entirely in the western United States and in As. ia, dinosaur fossils are now being discovered on all seven co
admin
2010-03-25
60
问题
Once found almost entirely in the western United States and in As. ia, dinosaur fossils are now being discovered on all seven continents. A host of new revelations emerged in 1998 that promise to reshape scientists’ views of dinosaurs, including what they looked like and when and where they lived.
It is doubtful that Tyrannosaurus Rex had lips or that Triceratops had cheeks, says Lawrence Witmer, an assistant professor of anatomy at Ohio University in Athens, Ohio. Witmer was a leading researcher for a study on dinosaur anatomy that was presented at the annual meeting of the Society for Vertebrate Paleontology, which concluded on October 3 in Snowbird, Utah.
Witmer’s study reached its conclusions by using high-tech computerized axial tomography (CT or CAT) scans along with comparative anatomy studies. For example, the theory that Triceratops and similar dinosaur species had cheeks was based on past comparisons with mammals such as sheep. But Witmer’s careful analysis found the structure of the triceratops jaw and skull made it more likely that Triceratops had a beak like that of an eagle. Witmer said that scientists should use birds and crocodiles as models when researching the appearance of dinosaurs.
In early October scientists announced that they had confirmed the discovery of a new type of ceratopsian dinosaur. The dinosaur’s bones, found in New Mexico in 1996, are forcing paleontologists to rethink their theories about when eeratopsians migrated to what is now North America.
Scientists previously thought that ceratopsians, the group that included the well known Triceratops, arrived in North America from Asia between 70 million and 80 million years ago. During this time, the late Cretaceous Period, the earth’s two supercontinents—Laurasia in the north and Gondwanaland in the south—were in the process of pulling apart, cutting dinosaur populations off from each other and interrupting migratory patterns.
The fossilized bones, found by eight-year-old Christopher Wolfe and his father, paleontologist Doug Wolfe of the Mesa Southwest Museum in Arizona, date to about 90 million years ago. This could mean that ceratopsians originated in North America and migrated to Asia rather than the reverse, paleontologists said. Doug Wolfe named’ the important new species of dinosaur Zuniceratops Christopheri after his son.
An expedition from the Universities of Alaska in Anchorage and Fairbanks has discovered a region in remote northern Alaska so rich in fossilized dinosaur tracks that team members dubbed it the "dino expressway". The trampled area was found during the summer of 1998 on Alaska’s North Slope near the Brooks Range.
The team found 13 new track sites and made casts from the prints of five different types of dinosaurs. The rock in which the prints were found dates to more than 100 million years ago, or about 25 million years older than the previously discovered signs of dinosaurs in the Arctic region. Paleontologists said that the new findings provide important evidence that dinosaurs migrated between Asia and North America during the early and mid-Cretaceous Period, before Asia split off into its own continent.
Two rich fossil sites in the hills of Bolivia have been recently discovered, exciting paleontologists and dinosaur buffs. This discovery includes one of the most spectacular dinosaur trackways ever found.
The discovery of a large site in the mountain region of Kila Kila in southern Bolivia was announced in early October. Here scientists found the tracks of at least two unknown species of dinosaur. These included a large quadruped (four-footed) dinosaur that was probably about 20m (about 70 ft) long.
The other site, located not far from the Bolivian city of Sucre, was uncovered in a cement quarry by workers several years ago but was not brought to paleontologists’ attention until the middle of 1998. The site features a vertical wall covered with thousands of dinosaur prints representing more than 100 different species. The tracks date back to between 65 million and 70 million years ago. Since dinosaurs are believed to have died out around 65 million years ago, the prints were likely made by some of the last dinosaurs on earth.
Scientists speculated that the tracks were made at the edge of a lake or swamp and were then hardened and preserved. The rock containing the tracks was then pushed into a vertical position over millions of years of geologic activity. Dinosaur eggs have also been found at the site, which paleontologists are working to preserve before it falls victim to erosion. Paleontologists hope to study the site and learn about the diet and physical characteristics of the dinosaurs that are represented there.
The passage focuses on
选项
A、dinosaurs’ geographical location.
B、shifting views of dinosaurs.
C、migration patterns of dinosaurs.
D、geologic activity of Earth.
答案
B
解析
关于本文的重点,可以从文章首段内略见一斑:“A host of new revelations emerged in 1998 that promise to reshape scientists’views of dinosaurs,including what they looked like and when and where they lived.”而且以后部分讲述了最近的几次重大发现,其结果是使科学家改变了许多对恐龙原来的认识,因此B较为正确。其他选项的内容文中都有涉及,但都是为主题服务的。
转载请注明原文地址:https://kaotiyun.com/show/2TqO777K
0
专业英语八级
相关试题推荐
Intheinformationtechnologyindustry,itiswidelyacknowledgedthathowwellITdepartmentsofthefuturecanfulfiltheirbu
Longbeforerecordedhistory,ourancestorswerebathingforpleasureandhealth.Manhasfoundmanyinterestingwaystotakehi
AnyrequestintheUnitedKingdomtoremoveadisabledperson’sabilitytoreproduceshouldbetreatedwithgreatcaution.Then
Tenyearsago,insettlingthelargestcivillawsuitintheUShistory,thetobaccoindustryagreedtopaythe50states$246bi
Howmuchmuseumgoersknowaboutartmakeslittledifferenceinhowtheyengagewithexhibits,accordingtoastudybyaGermanc
A、BecauseshewantedtoinvitehimtoSpain.B、Becausesheneededsomehelptofindahotel.C、Becausesheaskedhimtobookah
NapoleonfamouslydescribedtheBritishasanationofshopkeepers.Thesedaysitwouldbeequallytruetodescribethemasana
悉尼(Sydney)是个非常现代化的城市,但也有许多历史名胜古迹。在市中心,你依然可以看到一些很久以前就建造在那里的老房子。
金融危机爆发以来,国际组织和各国政府都在深刻反思,寻求世界经济和各国经济未来发展之路。对中国经济发展的成就,有喝彩的,也有怀疑的;对中国经济的未来,有看好的,也有唱衰的。对此,我们的头脑是清醒的,信心是坚定的。我们坚持用改革的办法破解发展难题,不
GoalTrimmerUtopiasaresupposedtobedreamsofthefuture.ButtheAmericanUtopia?Latelyit’sadreamthatwas,atwilit
随机试题
下列属大体积混凝土温度裂缝的是()。
升华指一个人将受挫后的心理压抑向符合社会规范的、具有建设性意义的方向抒发的心理反应。根据上述定义,下列属于升华的是:
ZA-312型大钩的起重量是()。
胃溃疡底部最常见动脉内血栓机化,该处血栓形成的最主要机制是()
根据《劳动防护用品监督管理规定》的有关规定,劳动防护用品生产企业所生产的特种劳动防护用品,必须取得特种劳动防护用品(),否则不得生产和销售。
下列不属于基金管理人后台部门的是()。Ⅰ.清算部门Ⅱ.投资部门Ⅲ.研究部门Ⅳ.产品研发部门
有一种捉猴子的陷阱,即把椰子挖空,然后用绳子绑起来,接在树上或固定在地上,椰子上留了一个小洞,洞里放了一些食物。洞口大小恰好只能让猴子空着手伸进去,而无法握着拳头伸出来,于是猴子闻香而来,将它的手伸进去抓食物,理所当然地,紧握的拳头便缩不出洞口,当猎人来时
某些经济学家是大学数学系的毕业生。因此,某些大学数学系的毕业生是对企业经营很有研究的人。下列哪项如果为真,则能够保证上述论断的正确?
ROM主要用于永久保存路由器的开机诊断程序、()和()软件。
AnewWorldBankstudysaysinternationalmigrationhelpsreducepovertyindevelopingnations.Atthesametime,however,many
最新回复
(
0
)