麥爾利維坦鯨/麥爾維爾鯨(Leviathan melvillei)正模標本被發現於秘魯伊卡沙漠科羅拉多山丘（Cerro Colorado）皮斯科組及Chilcatay組之間 ,  化石屬中新世中期(1400萬年前至1200萬年前) , 於當地也發現了其它齒鯨類化石包括簇狀馬什喙鯨(Messapicetus gregarious)及馬澤亞斯短吻河豚(Brachydelphis mazeasi),此外也發現了須鯨類殘骸 , 海龜 , 海鳥 ,硬骨魚類及大型鯊類如寬齒鯖鯊(Cosmopolitodus hastalis)及巨齒鯊(Carcharocles megalodon)等化石。

 

現存的抹香鯨(Physeter macrocephalus)主要以深海的頭足類為食 , 由於缺少上頜的牙齒 , 因此主要以抽吸方式來抓捕獵物 , 相反體型較小的中新世抹香鯨總科屬種比如顴突抹香鯨屬(Zygophyseter) , 管狀鯨屬(Acrophyseter) , 奧巴斯托鯨屬(Orycterocetus)及阿普裏斯小抹香鯨屬(Aprixokogia)上下頜均具有牙齒 , 牠們則類似今天的逆戟鯨般迅速抓捕獵物。許多地區都有較大的抹香鯨類牙齒被發現但是大多沒有發現顱骨殘骸 , 不過麥爾利維坦鯨(Leviathan melvillei)正好提供了史前的大型掠食性抹香鯨類的真正麵貌。

 

麥爾利維坦鯨 (Leviathan melvillei)有部分頭骨 , 下頜及牙齒化石發現 , 整個頭部長約3米 , 有非常大的上頜及下頜牙齒 , 最大的牙齒長約36厘米及寬達12厘米 , 有粗狀的頜骨 , 顳窩(temporal fossa)比今天的抹香鯨要大顯示麥爾利維坦鯨 (Leviathan melvillei)有極大的咬合力。由於中新世時期須鯨類迅速分化並且體型開始變大 , 麥爾利維坦鯨 (Leviathan melvillei)被認為會捕食中小型須鯨類 , 牠們甚至和可怕的巨齒鯊(根據新的公式推算最大可達20米)存有激烈的競爭。麥爾利維坦鯨 (Leviathan melvillei) 有廣闊的骨盆(supracranial basin )並延至吻突之上 , 這顯示牠可能是存有鯨腦油但和深潛或以抽吸方式抓捕獵物沒關。

 

分類上長野鯨屬(Brygmophyseter)及顴突抹香鯨屬(Zygophyseter)屬抹香鯨總科莖層成員(stem physeteroids) , 利維坦鯨屬 (Leviathan)的位置還是沒定論 , 不過牠看似應該是被放置於小抹香鯨科及抹香鯨科以外的位置。

 

華路拿顴突抹香鯨(Zygophyseter varolai) 顱長148cm , 顴骨寬度約74.5cm , 全長約650 至 700 cm , 根據現存的抹香鯨 (體長BL 減顱長CBL)和顴骨寬度關係的公式 , 再以華路拿顴突抹香鯨(Zygophyseter varolai)的數據比例來估算 , 麥爾利維坦鯨 (Leviathan melvillei)全長約1621 cm至1753 cm。

 

Los Angeles -- Paleontologists digging near the coast of Peru have uncovered the largest fossilized skull of a sperm whale ever found.

The 12-million-year-old skull _ which measures nearly 10 feet across _ belonged to a now-extinct genus and species of sperm whale that could have been as much as 57 feet long. The fossil includes the longest documented sperm whale teeth, measuring more than 14 fearsome inches.

 

The whale, described in a paper published Thursday in the journal Nature, was christened Leviathan melvillei in honor of Moby Dick author Herman Melville.

 

The creature "was certainly a top predator, probably occupying the same ecological niche of the living killer whale," said Olivier Lambert, one of the study's lead authors and a paleontologist at the National Museum  of Natural History in Paris.

 

Modern sperm whales may grow to about the same size as Leviathan melvillei, but they dive deep into the ocean to feed on squid using suction.

 

The older whale, on the other hand, may have used its sharp teeth to rip into mid-size baleen whales.

 

"That's a provocative idea," said Ewan Fordyce, a paleontologist specializing in whales and dolphins at the University of Otago in New Zealand who was not involved in the discovery.

 

"If that's how it fed, it fed very differently from the modern sperm whale," he said. "It opens our eyes about the diversity of feeding habits."

 

Lambert said the fossil, which his team uncovered during the last few hours of the final day of digging on a 2008 research field trip, gives researchers a better picture of the diversity of marine mammalian life millions of years ago.

 

But the reason for their demise remains a mystery. Perhaps their great size became a detriment, he said.

 

"When you become bigger it becomes difficult to attack smaller animals," he said.

 

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編輯：劉琮瀅