The world’s biggest-ever bird weighedas much as a cow and lived in Australia until50，000 years ago.

The flightless Dromornis stirtoni1plodded along on two hind legs. It was thelargest member of an extinct group ofcreatures called the mihirungs—based on anAboriginal word for giant2 bird.

In a new research， scientists describedhow they analysed3 the ancient skulls4 ofmihirungs to get a better idea of their brains.

They discovered that the animals’hugeheads left little room for brains， giving riseto some strangely shaped skulls.

“Together with their large， forward -facing eyes and very large beaks5， the shapeof their brains and nerves suggested thesebirds likely had well-developed depth perception6and fed on a diet of soft leaves andfruit，”said study lead author.

世界上最大的鳥有一頭牛那么重，它5 萬年前生活在澳大利亞。

不會飛的史氏雷嘯鳥用兩條后腿緩慢前行。它是一個滅絕的生物群mihirungs（原住民語“巨鳥”的意思）中最大的一個，這個生物群的名字來源于土著人對巨型鳥的稱呼。

在一項(xiàng)新研究中，科學(xué)家們描述了他們是如何分析巨鳥的遠(yuǎn)古頭骨來更好地了解它們的大腦的。

他們發(fā)現(xiàn)，這些動物巨大的頭部幾乎沒有給大腦留下空間，因此產(chǎn)生了一些形狀奇特的頭骨。

這項(xiàng)研究的主要作者說：“加上它們前視的大眼睛和非常大的喙，它們的大腦和神經(jīng)的形狀表明，這些鳥可能有很好的深度感知能力，并且以柔軟的樹葉和水果為食。”

“The shape of their brains and nerveshave told us a lot about their sensorycapabilities7， and something about theirpossible lifestyle which enabled theseremarkable8 birds to live in the forestsaround river channels9 and lakes acrossAustralia for a very long time.”

Nicknamed“Thunder Birds”， mihirungs lived across Australia for millions of years.

The largest species Dromornis stirtoni could grow to 3m tall and weigh about 600kg.

The researchers discovered thatmihirung brains and nerves10 were most likethose of modern day chickens andAustralian malleefowl11.

“The unlikely truth is these birds wererelated to chickens and ducks， but theirclosest cousin and much of their biologystill remains a mystery，”said study authorDr. Trevor Worthy.

“它們的大腦和神經(jīng)的形狀告訴了我們很多關(guān)于它們的感知能力，以及它們可能的生活方式的一些信息，這種生活方式使這些非凡的鳥類能夠在澳大利亞的河流和湖泊周圍的森林中生活很長一段時間?！?/p>

這些巨鳥被稱為“象鳥”，在澳大利亞生活了數(shù)百萬年。

最大的物種史氏雷嘯鳥可以長到3 米高，約600 公斤重。

研究人員發(fā)現(xiàn)，巨鳥的大腦和神經(jīng)與現(xiàn)代雞和澳大利亞眼斑冢雉最為相似。

研究報告的作者特雷弗·沃西博士說：“難以置信的事實(shí)是，這些鳥類與雞、鴨有親緣關(guān)系，但它們最近的近親以及它們的大部分生物學(xué)特性仍然是一個謎?！?/p>

The team used CT scans of the skulls to create casts of the creatures’brains.

The largest and last species Dromornisstirtoni， which died out 50，000 years ago， wasan “extreme evolutionary12 experiment”， DrWorthysaid.

“This bird had the largest skull butbehind the huge bill was a strangecranium13，”he explained.

“To accommodate14 the muscles towield15 this huge bill， the cranium hadbecome taller and wider， and so the brainwithin was squeezed16 and flattened17 to fit.”

研究小組對這些頭骨進(jìn)行了CT 掃描，建立了這些動物的大腦模型。

最大也是最后的物種史氏雷嘯鳥在5 萬年前就滅絕了，這是一個“極端的進(jìn)化實(shí)驗(yàn)”，沃西博士這么說。

“這只鳥有最大的頭骨，但在巨大的喙后面有一個奇怪的頭蓋骨?！彼忉屨f。

為了容納肌肉揮舞這張大嘴，它們的頭蓋骨變得越來越高，越來越寬，因此內(nèi)部的大腦隨之被擠壓扁平?！?/p>

（英語原文選自：kidsnews.com.au）