亚洲人成网站18禁止中文字幕,国产毛片视频在线看,韩国18禁无码免费网站,国产一级无码视频,偷拍精品视频一区二区三区,国产亚洲成年网址在线观看,国产一区av在线

--- SEARCH ---
WEATHER
CHINA
INTERNATIONAL
BUSINESS
CULTURE
GOVERNMENT
SCI-TECH
ENVIRONMENT
SPORTS
LIFE
PEOPLE
TRAVEL
THIS WEEK
Learning Chinese
Learn to Cook Chinese Dishes
Exchange Rates


Hot Links
China Development Gateway
Chinese Embassies

Scientists Resolve Dinosaur Sex Riddle

A Tyrannosaurus rex recently excavated in Montana, US has surprised scientists. A layer of medullary bone found inside the leg bones of the animal -- a most improbable discovery after 70 million years -- showed it was an ovulating female.

 

The finding provides a way to tell at least some dinosaurs' sexes. Until now, distinguishing the sex of dinosaurs has been impossible without well-preserved pelvic bones.

 

Medullary bone is a calcium-rich layer that develops in the long bones of birds during the egg-laying process. It provides a supply of calcium to form eggshells.

 

Moreover, after careful testing, the scientists led by Mary Schweitzer of North Carolina State University determined that the estrogen-derived tissue was similar to substances now present only in living birds that produce eggshells.

 

The team concludes in a report in Friday's issue of the journal Science that the finding "solidifies the link between dinosaurs and birds" and "provides an objective means of gender differentiation in dinosaurs."

 

This discovery won't enable paleontologists to determine the sex of all dinosaurs, however, since medullary bone is present only during the egg-laying cycle. But when it is present, it at least enables them to say that particular example is female.

 

(Xinhua News Agency June 6, 2005)

 

 

Dinosaur Fossil Discovered in Jiangxi
Bird-like Eggs Found in Dinosaur Fossil
Heyuan, Hometown of the Dinosaur
Fossilized Dinosaur Eggs Discovered in Hubei
Heyuan Museum Listed in Guinness World Records
Scientists Find Dinosaur-eating Mammal
Print This Page
|
Email This Page
About Us SiteMap Feedback
Copyright © China Internet Information Center. All Rights Reserved
E-mail: webmaster@china.org.cn Tel: 86-10-68326688
    1. <ul id="556nl"><kbd id="556nl"><form id="556nl"></form></kbd></ul>
      <thead id="556nl"></thead>

      1. <em id="556nl"><tt id="556nl"></tt></em>
        <ul id="556nl"><kbd id="556nl"><form id="556nl"></form></kbd></ul>

        <ul id="556nl"><small id="556nl"></small></ul>
        1. <thead id="556nl"></thead>

          亚洲人成网站18禁止中文字幕,国产毛片视频在线看,韩国18禁无码免费网站,国产一级无码视频,偷拍精品视频一区二区三区,国产亚洲成年网址在线观看,国产一区av在线 人妻无码久久影视 日韩久久久久久久久久久久 精品国产香蕉伊思人在线 无码国产手机在线a√片无灬 91在线视频无码