VOA慢速英语--科学家发现了一些恐龙是如何长得这么大的

Scientists studying the remains¹ of ancient creatures say that large dinosaurs³ did not grow at the same rate.

Some dinosaurs grew slowly and steadily⁴. Others experienced a growth spurt⁵ as they neared adulthood⁶. A "growth spurt" is when something or someone grows very quickly. For example, children usually have a growth spurt between the ages of 12 and 18.

The same appears to be true for some dinosaurs!

The research appeared recently in the Proceedings⁷ of the Royal Society B publication.

To reach their findings, scientists cut through the fossilized bones of dinosaurs. They examined the yearly growth rings of the bones from 11 kinds of theropods. Theropods are a group of dinosaurs that mainly walked on two legs and include big meat-eating dinosaurs, like tyrannosaurus rex, commonly known as T. rex.

Reuters news agency reports that this new study provides a look into the lives of some of the most fearsome hunters ever to walk the Earth.

The research team looked at fossils from museums in the United States, Canada, China, and Argentina. They were able to cut into the fossilized bones of one of the world's most famous T. rexes, known as Sue. Sue is housed at the Field Museum in Chicago.

The researchers used machines to cut into Sue's largest leg bones. These bones showed that the T. rex and its relatives - known as tyrannosaurs - have a period of extreme growth during the years before adulthood. It also shows that they reached full adult size by around age 20.

Sue is about 13 meters tall. She is believed to have lived to about 33 years. She lived in an area that is modern day South Dakota, a state in the north-central part of the United States.

Other groups of large theropods had more steady rates of growth over a longer period of time. Examples of these include two kinds of North American dinosaurs -- Allosaurus and Acrocanthosaurus.

Another dinosaur² from Antarctica, Cryolophosaurus and a dinosaur recently discovered in Argentina also grew slowly.

The Argentinian dinosaur has not yet been named, but it was as big as a T. rex. This dinosaur did not reach its full adult size until it reached about 40 years of age. It is believed to have lived to about age 50.

Big theropods share the same basic body design. They walked on two legs and had large skulls⁸ and strong jaws⁹. And of course, they had threatening teeth.

The lead researcher on the study is Tom Cullen. He is a paleontologist with the North Carolina Museum of Natural Sciences and North Carolina State University.

He said that before this study, "it was known that T. rex grew very quickly, but it was not clear if all theropod dinosaurs reached gigantic size in the same way," or if there were many ways they grew so big.

Words in This Story

steadily –adv. not changing very much over time

fossilized –adj. tissue that has changed into a mineral underground over time

paleontologist –n. a scientist who studies fossils of animals that lived a very long time ago

gigantic –adj. extremely large

1 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

2 dinosaur   

n.恐龙

参考例句：

• Are you trying to tell me that David was attacked by a dinosaur?你是想要告诉我大卫被一支恐龙所攻击？
• He stared at the faithful miniature of the dinosaur.他凝视著精确的恐龙缩小模型。

3 dinosaurs   

n.恐龙( dinosaur的名词复数 )；守旧落伍的人，过时落后的东西

参考例句：

• The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
• Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》

4 steadily   

adv.稳定地；不变地；持续地

参考例句：

• The scope of man's use of natural resources will steadily grow.人类利用自然资源的广度将日益扩大。
• Our educational reform was steadily led onto the correct path.我们的教学改革慢慢上轨道了。

5 spurt   

v.喷出；突然进发；突然兴隆

参考例句：

• He put in a spurt at the beginning of the eighth lap.他进入第八圈时便开始冲刺。
• After a silence, Molly let her anger spurt out.沉默了一会儿，莫莉的怒气便迸发了出来。

6 adulthood   

n.成年，成人期

参考例句：

• Some infantile actions survive into adulthood.某些婴儿期的行为一直保持到成年期。
• Few people nowadays are able to maintain friendships into adulthood.如今很少有人能将友谊维持到成年。

7 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

8 skulls   

颅骨( skull的名词复数 )； 脑袋； 脑子； 脑瓜

参考例句：

• One of the women's skulls found exceeds in capacity that of the average man of today. 现已发现的女性颅骨中，其中有一个的脑容量超过了今天的普通男子。
• We could make a whole plain white with skulls in the moonlight! 我们便能令月光下的平原变白，遍布白色的骷髅！

9 jaws   

n.口部；嘴

参考例句：

• The antelope could not escape the crocodile's gaping jaws. 那只羚羊无法从鱷鱼张开的大口中逃脱。
• The scored jaws of a vise help it bite the work. 台钳上有刻痕的虎钳牙帮助它紧咬住工件。