VOA慢速英语2019 霸王龙从儿童大小的恐龙演变而来（在线收听）

Tyrannosaurus Rex Developed from a Child-Sized Dinosaur

History’s most frightening dinosaur, the Tyrannosaurus rex, came from a long line of smaller creatures.

Scientists have identified a new relative of the Tyrannosaurus rex, also known as T. rex. Scientists say this relative was only about one-meter high, the height of a small child.

American Sterling Nesbitt, a paleontologist, discovered the dinosaur. He told the Associated Press that if the ancient creature raised its head, an adult human maybe “would be looking at it in the eye.”

Nesbitt is with the Virginia Polytechnic Institute and State University in Blacksburg, Virginia. In 1998, he found the creature’s remains while serving as a volunteer on a dig in New Mexico with a famous paleontologist. At the time, Nesbitt was just 16 years old.

For about 20 years, scientists were not sure what to make of the remains, until other small relatives of T. rex were discovered.

“The small group of tyrannosauroid dinosaurs would give rise to some of the biggest predators that we’ve ever seen,” noted Nesbitt. He is the lead author of a report of the bones. The findings were published earlier this month in the scientific journal Nature Ecology and Evolution.

The new dinosaur is called Suskityrannus hazelae. The name comes from a word in the language of the Zuni, a Native American tribe. It describes another small, but modern predator: the coyote.

Scientists say the dinosaur dates back 92 million years, about 20 million years before the T. rex walked the Earth. The newly discovered cousin weighed between about 20 and 40 kilograms. It was three times longer than it was tall. That is almost nothing compared to the nine-ton T. rex.

Suskityrannus hazalae is not the first or even smallest member of the Tyrannosaurus family tree. But Nesbitt said it provides the best example of how this family of smaller dinosaurs evolved into the frightening star of movies and television shows.

Hans-Dieter Sues is a paleobiologist with the Smithsonian Institution in Washington. He suggested it was an important find.

“Suskityrannus is the first really good record of the early tyrannosaurs in North America,” he wrote in an email. He was not involved in the study.

Scientists are not sure why these meat-eaters were not especially big compared with other dinosaurs alive at the time. So it is unclear why they later evolved to be so huge.

Nesbitt said the newly discovered species is probably among the last of the little dinosaurs. It was bigger than earlier members of the species and had big feet needed for speed — something the T. rex lost.

历史上最可怕的恐龙霸王龙起源于小型生物。

科学家发现了霸王龙（简称T. rex）的新亲属。科学家表示，这一亲属只有大约1米高，这一高度与小孩的身高差不多。

美国古生物学家斯特林·内斯比特发现了这种恐龙。他对美联社表示，如果这种古代生物抬起头，那成年人也许“可以与其对视”。

内斯比特来自位于弗吉尼亚州布莱克斯堡的弗吉尼亚理工学院暨州立大学。他在1998年发现了这种生物的化石残骸，当时他作为志愿者与一位著名古生物学家共同参与了新墨西哥州的挖掘工作。那一年，内斯比特只有16岁。

在此后近20年的时间里，科学家一直无法确定这一化石残骸的身份，直到霸王龙的其他小型亲属相继被发现。

内斯比特表示，“这一小群霸王龙可能演化成了我们见过的最大的捕食者。”内斯比特是一份涉及所发现骨架化石报告的主要作者。这份报告于本月早些时候发表在科学期刊《自然·生态学与进化》上。

新发现的恐龙名为黑兹尔郊狼暴龙。这一名称来源于祖尼语的一个单词，祖尼是美洲土著部落。这个词描述了另一个体型小的现代掠食者：郊狼。

科学家表示，这种恐龙生活在9200万年前，而大约2000万年之后，霸王龙才出现在地球上。新发现的霸王龙近亲体重在20到40公斤之间。这一数字是其体长的3倍。但完全无法与9吨重的霸王龙相比。

黑兹尔郊狼暴龙不是霸王龙家族中的首个成员，甚至不是身型最小的成员。但内斯比特认为，这一物种为霸王龙家族如何进化为最令人害怕的影视明星提供了最佳例证。

汉斯-迪特尔·苏斯是华盛顿史密森学会的古生物学家。他认为这是一项重要发现。

他在电邮中写道，“郊狼暴龙是北美早期霸王龙的首个最佳记录。”他并未参与研究。

目前科学家还未确定的是，为何与当时生活在地球上的其它恐龙相比，这些肉食动物的体型并不是特别大。也就是说，现在并不清楚它们之后为什么会进化为巨型恐龙。

内斯比特表示，新发现的物种可能是最后一只小恐龙。它比同一物种的早期成员体型要大，而且还有奔跑速度所需的大脚——而这是霸王龙所没有的。

Words in This Story

paleontologist – n. a scientist who studies the remains of animals and plants that lived very long ago especially in the time of dinosaurs

predator(s) – n. an animal that lives by killing and eating other animals

author – n. a person who has written something

journal – n. a magazine that reports on things of special interest to a particular group of people

coyote – n. a small wild animal that is related to dogs and wolves and that lives in North America

evolve(d) – v. to change or develop slowly often into a better, more complex, or more advanced state

paleobiologist – n. a scientist who studies the biology of animals and plants that lived very long ago especially in the time of dinosaurs