LYRICS
The brains of today's birds show a level of intelligence and behavioral complexity rivaled only by mammals.
现代鸟类的大脑表明它们拥有只有哺乳动物才能匹敌的智力和行为复杂性。
But scientists do not fully understand how bird brains have changed over millions of years from the form they had as dinosaurs.
但是科学家们并不完全了解，在数百万年的时间里，鸟类的大脑是如何从它们的祖先恐龙演化而来的。
That understanding is now growing thanks to a fossil discovery in Brazil.
多亏了在巴西发现的化石，这种理解有所加深。
Researchers unearthed the remains, or fossil, of a head bone, or skull, of a bird species not known before. It has been named Navaornis hestiae.
研究人员发掘出了一种以前不为人知的鸟类的头骨遗骸或化石。它被命名为“Navaornis hestiae”。
The fossil was in such good condition that scientists were able to create a computer image of its brain and inner ear structures.
这具化石保存得非常完好，科学家们能用电脑制作出它的大脑和内耳结构的图像。
It lived in a dry area about 80 million years ago during the Cretaceous Period, near the end of the age of dinosaurs.
它生活在大约8000万年前的白垩纪，也就是恐龙时代末期的一个干燥地区。
"This finding is one-of-a-kind," said University of Cambridge fossil expert Guillermo Navalón, a lead researcher of the study.
“这一发现是独一无二的，”剑桥大学化石专家吉列尔莫·纳瓦隆说，他是这项研究的首席研究员。
It appeared this month in the publication Nature.
该研究发表在本月的《自然》杂志上。
Birds developed from small, feathered dinosaurs during the Jurassic Period.
鸟类是由侏罗纪时期长有羽毛的小型恐龙进化而来的。
The Navaornis discovery filled in a 70-million-year gap in the understanding of the development of the bird, dating back to the earliest-known bird Archaeopteryx.
Navaornis这次发现填补了人们对这种鸟类在演化上长达7000万年的空白，这种鸟类可以追溯到已知的最古老的鸟类始祖鸟。
It lived about 150 million years ago in what is now Europe.
它生活在大约1.5亿年前的欧洲。
The researchers said the Navaornis skull has a bill and eye shape like modern birds.
研究人员表示，Navaornis头骨上的喙和眼睛形状与现代鸟类相似。
Its brain shows both modern and ancient elements, and some that are in between.
它的大脑既有现代特质，也有古代特质，还有一些介于两者之间。
Luis Chiappe is a fossil scientist at the Natural History Museum of Los Angeles County in California and a co-writer of the study.
路易斯·齐亚比是加州洛杉矶县自然历史博物馆的化石科学家，也是这项研究的合著者。
He said scientists rarely find such skulls of early birds, "and this one is the best preserved ever."
他说，科学家们很少发现这样的早期鸟类头骨，“这是迄今保存最完好的一个。”
Daniel Field is a fossil scientist at the University of Cambridge and the study's lead writer.
丹尼尔·菲尔德是剑桥大学的化石科学家，也是该研究的主要作者。
He said scientists have long struggled to understand how and when the brains and intelligence of birds developed.
他说，长期以来，科学家们一直在努力了解鸟类的大脑和智力是如何以及何时发展起来的。
"The field has been awaiting the discovery of a fossil exactly like this one," he said.
他说：“这个领域一直在等待发现一个像这次这样的化石。”
The Navaornis brain - measuring about 10 millimeters across - is smaller, relative to skull size, than that of modern birds.
Navaornis的大脑直径约为10毫米，与头骨的尺寸相比，它比现代鸟类要小一些。
But the skull is larger and more complex than that of Archaeopteryx.
但它的头骨比始祖鸟的更大更复杂。
Its cerebellum, a brain structure that in living birds helps with motor control during flight, was smaller than in today's bird species and more like Archaeopteryx's.
它的小脑比今天的鸟类要小，更像始祖鸟一些。小脑是帮助鸟类控制飞行时运动的大脑结构。
But its brain was connected to the spinal cord in a way similar to modern birds, as well as humans.
但它的大脑与脊髓的连接方式与现代鸟类和人类相似。
It was unlike Archaeopteryx and the dinosaurs from which birds evolved.
与始祖鸟和鸟类的祖先恐龙不同。
Navaornis also had something special – its inner ear organ for balance is larger than in any other known bird.
Navaornis还有一些特别之处——它的内耳平衡器官比任何已知的鸟类都要大。
The fossil included 80 percent of the bird's bone structure, or skeleton.
这块化石包含了这种鸟80%的骨骼结构。
The scientists say they believe the bird could fly well based on their examination of the remains.
科学家们说，根据他们对化石遗骸的检查，他们相信这只鸟的飞行能力很强。
Its name means "Nava's bird," named for William Nava, the scientist who discovered the fossil in 2016 in the southeastern Brazilian state of Sao Paulo.
它的名字意为“纳瓦的鸟”，以2016年在巴西东南部圣保罗州发现化石的科学家威廉·纳瓦命名。
Navaornis lived during the Cretaceous period, but none of these birds survived the asteroid strike that took place 66 million years ago.
Navaornis生活在白垩纪，但这些鸟都没有在6600万年前的小行星撞击中幸存下来。
That means there is no direct line from Navaornis to today's birds, and its modern-looking abilities and appearance developed separately from theirs.
这意味着Navaornis与今天的鸟类没有直接联系，而且它的现代外观和能力与如今的鸟类是分开发展的。
The researchers said the bird ate insects and seeds it could take in whole.
研究人员说，这种鸟吃昆虫和种子，而且可以整个吞掉。
It lived side-by-side with huge, long-necked plant-eating dinosaurs and large meat-eating dinosaurs.
它与巨大的长颈食草恐龙和大型食肉恐龙生活在一起。
Field said if you gave it a quick look you might think it was like a living bird.
菲尔德说，乍一看，你可能会觉得它是一只现代的鸟。
But a closer look would show you some important differences – like claws coming out of its wings.
但仔细观察就会发现一些重要的区别——比如它的爪子是从翅膀上伸出来的。
I'm Jill Robbins.
吉尔·罗宾斯报道。
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