英语翻译A Dino King's AncestorTyrannosaurus rex gets a lot of attention for being one of the fiercest large dinosaurs that ever lived.These fearsome meat eaters,however,weren't the first of their kind.In northwestern China,paleontologists have fo

英语翻译A Dino King's AncestorTyrannosaurus rex gets a lot of attention for being one of the fiercest large dinosaurs that ever lived.These fearsome meat eaters,however,weren't the first of their kind.In northwestern China,paleontologists have fo
英语翻译
A Dino King's Ancestor
Tyrannosaurus rex gets a lot of attention for being one of the fiercest large dinosaurs that ever lived.These fearsome meat eaters,however,weren't the first of their kind.
In northwestern China,paleontologists have found remains of Guanlong wucaii,the oldest known dinosaur that belongs to the tyrannosaur family.The name means "crowned dragon from the five-colored rocks," and the species lived about 160 million years ago.
G.wucaii were only 3 meters (9.8 feet) long,but they were probably ancestors of the much larger T.rex,which lived 95 million years later,researchers say.
In China,the researchers found two G.wucaii skeletons that were nearly complete.One appeared to be a 12-year-old adult.The other was a 6-year-old youngster.Each one had a hollow,bony crest running along the top of its snout.
The crest,which was 6 centimeters (2.4 inches) tall on the adult (and smaller on the juvenile),baffles scientists.The crest wasn't connected to the creature's nose.Nor did it appear to be useful for fighting.Instead,it's possible that the structure served as a sign of adulthood or a way for the animals to tell the difference between males and females.It could have also helped them recognize members of their own species.
The new fossils shed light on debates about tyrannosaur evolution.Paleontologists used to think that T.rex and its cousins evolved from huge predators that lived 145 million years ago.Now,it appears that tyrannosaurs evolved much earlier than that,from a group of small,meat-eating dinos called coelurosaurs.
G.wucaii fit somewhere in the middle,sharing traits with both groups.It had tyrannosaur-like teeth in the front of its jaws and nasal bones that were fused together to strengthen its skull.But it also had the coelurosaur's long snout,bladelike teeth on the sides of its jaws,and long arms with three-fingered hands that could grasp objects.
Also unlike T.rex,G.wucaii had to hold its own in a harsh world.During its time on the planet,it faced predators twice its size.

英语翻译A Dino King's AncestorTyrannosaurus rex gets a lot of attention for being one of the fiercest large dinosaurs that ever lived.These fearsome meat eaters,however,weren't the first of their kind.In northwestern China,paleontologists have fo
暴君恐龙的祖先
暴龙（也称暴君蜥蜴或霸王龙）是地球上出现过的最残暴的大型食肉恐龙.因此它广受人们关注.然而,这些骇人的肉食动物也有它们自己的祖先.
古生物学家在中国西北部找到了“五彩冠龙”的残骸.它属于暴龙目暴龙科,是这个家族中已知的最古老的恐龙.“五彩冠龙”顾名思义——一种头上长冠的从五彩岩石中发掘出来的龙.这一物种生活在距今一亿六千万年前.
“五彩冠龙”身长只有3米（9.8英尺）,但是研究者们认为它们很可能就是暴龙的祖先.暴龙的出现比“五彩冠龙”晚了九千五百万年,而且身躯也比它的祖先庞大的多.
研究者们在中国找到了两具几近完整的“五彩冠龙”骨架.其中一具属于一只生活了12年的成年恐龙,而另一具是一只年仅六岁的幼龄恐龙.两只恐龙各有一顶延伸至鼻子,中空的骨质头冠.
成年"五彩冠龙"头上的冠状物高6厘米（2.4英寸）（那只幼龄恐龙的冠要小一些）.然而这种奇特的头冠使科学家们大为不解.这种冠没有和恐龙的鼻子相连,也不像是用于争斗的武器.它可能是恐龙步入成年的一种象征性生理结构,或者是其种群内部辨别雌雄的一种标志.也有可能是用来和别的物种相区别的一种身体特征.
这一新化石的发现使有关暴龙进化的争论逐渐明晰.之前,古生物学家们认为暴龙与它的旁亲是由生活在距今一亿四千五百万年前的进化而来的.然而现在研究表明,暴龙的进化史要追溯到比先前早很多的小型食肉恐龙——虚骨龙.
"五彩冠龙"介于暴龙和虚骨龙两种恐龙之间,兼具两者的特征.在它的口腔前部长有像暴龙一样的尖牙,还有为使头骨更坚实而长合在一起的鼻骨.但是它还有和虚骨龙一样的一些特征：长鼻腔,颚的两侧还长有獠牙,长有三趾能够抓取物体的长长的前肢.
与暴龙不同之处还有,"五彩冠龙"必须在苛刻的环境中独自生存.在它的那个时代,其要面对的捕食者的体型是它的两倍.