冰天雪地中「失落的恐龍世界」

原文網址：www.sciencedaily.com/releases/2015/09/150922104639.htm

‘Lost world’ of cold weather dinosaurs discovered

冰天雪地中「失落的恐龍世界」

A Florida State University and University of Alaska Fairbanks research team has uncovered a new species of duck-billed dinosaur, a 30-footlong herbivore that endured months of winter darkness and probably experienced snow.

由佛羅里達州立大學和阿拉斯加大學費爾班克斯分校組成的研究團隊，發現了一種身長約30呎的新種鴨嘴龍，此草食性恐龍能夠度過數月之久的冬季永夜，甚至捱過風雪。

The skeletal remains of the dinosaurs were found in a remote part of Alaska. These dinosaurs were the northernmost dinosaurs known to have ever lived.

這些恐龍化石遺骸發現於阿拉斯加的偏遠地帶。牠們是已知的恐龍中生活在最北端者。

"The finding of dinosaurs this far north challenges everything we thought about a dinosaur's physiology," said FSU Professor of Biological Science Greg Erickson. "It creates this natural question. How did they survive up here?"

「在極北之境發現的這些恐龍，挑戰了目前為止我們對恐龍生理學的一切認知。」佛羅里達州立大學生命科學系的教授Greg Erickson說，「這自然而然地引起以下問題：牠們如何在那裏生存？」

The dinosaur is named Ugrunaaluk kuukpikensis, which means ancient grazer of the Colville River. The remains were found along the Colville River in a geological formation in northern Alaska known as the Prince Creek Formation.

這種恐龍被命名為Ugrunaaluk kuukpikensis，意指柯維爾河(Colville River)的遠古草食者。牠們的遺骸發現於阿拉斯加北部，柯維爾河沿岸的地層Prince Creek組當中。

The discovery is detailed in the Tuesday issue of the paleontology journal Acta Palaeontologica Polonica.

有關此發現的詳細敘述已於9月22日刊登在古生物期刊《波蘭古生物學報》(Acta Palaeontologica Polonica)當中。

"This new study names and brings to life what is now the most completely known species of dinosaur from the Polar Regions," said Patrick Druckenmiller, earth sciences curator of the University of Alaska Museum of the North and associate professor of geology at the University of Alaska Fairbanks.

「這項研究不但命名了在極圈發現的恐龍中我們所知最透徹者，也讓牠們重獲新生。」Patrick Druckenmiller說，他是阿拉斯加大學博物館地質科學組的主任，和阿拉斯加大學費爾班克斯分校地質系的副教授。

The dig site -- the Prince Creek Formation -- is a unit of rock that was deposited on an arctic, coastal flood plain about 69 million years ago.

挖掘遺址所在的地層，Prince Creek組為約6900萬年前沉積於北極一處沿海氾濫平原的岩層。

At the time the Prince Creek Formation was deposited, it was located well above the paleo-arctic circle, about 80 degrees north latitude. So, the dinosaurs found there lived as far north as land is known to have existed during this time period.

Prince Creek組沉積時的地理位置相當深入北極圈，約莫在北緯80度。因此，在這邊發現的恐龍為生存於同一時期的已知恐龍中，生活在最北陸者。

At the time they lived, Arctic Alaska was covered in trees because Earth's climate was much warmer as a whole. But, because it was so far north, the dinosaurs likely contended with months of winter darkness, even if it wasn't as cold as a modern-day winter. They lived in a world where the average temperature was about 43 degrees Fahrenheit, and they probably saw snow.

在牠們還活著的時候，地球整體的氣候相較於目前要暖和許多，因此北極圈內的阿拉斯加是被整片樹海覆蓋的。然而，即使冬季並不如現今這麼嚴寒，由於緯度甚高的緣故，牠們仍要在數個月的永夜之下求生。牠們生存的世界年均溫約莫華氏43度(攝氏6度左右)，而且相當有機會可以在那裏看到下雪。

"What we're finding is basically this lost world of dinosaurs with many new forms completely new to science," Erickson said.

「基本上，我們發現的這座「失落的恐龍世界」裡面包含了許多科學上前所未見的新物種。」Erickson說。

Since the 1980s scientists from the University of Alaska Museum of the North, and other collaborative institutions, including Florida State University, have collected more than 9,000 bones from various animals as part of the excavation of the Prince Creek Formation.

自1980年代起，來自阿拉斯加大學博物館和其他研究機構的科學家，包括佛羅里達州立大學，在挖掘Prince Creek組一部分的過程中，就已經採集了超過9000根來自各種動物身上的骨頭。

The majority of the bones of the Ugrunaaluk kuukpikensis were collected from a single layer of rock called the Liscomb Bonebed. The layer, about 2 to 3 feet thick, contains thousands of bones of primarily this one species of dinosaur.

Ugrunaaluk kuukpikensis大部分的骨頭採自於Liscomb Bonebed這層岩石。從這厚度僅僅2至3呎的岩石中挖掘出來的數千塊骨頭，幾乎都是這種恐龍的骨骸。

In this particular area, most of the skeletons were from younger or juvenile dinosaurs, about 9 feet long and three feet tall at the hip.

這個特殊區段中出土的骸骨大多來自於幼年或青壯年的恐龍個體，牠們的身長約9呎，臀高則約3呎。

Researchers believe a herd of juveniles was killed suddenly to create this deposit of remains.

研究人員認為某個突發事件殲滅了這群青春期的恐龍，而形成這段含有許多遺骸的沉積物。

Hirotsugu Mori, a former graduate student at UAF, completed a detailed analysis of the bone structure as part of his doctoral dissertation alongside Druckenmiller and Erickson.

之前於佛羅里達州立大學攻讀碩士的Hirotsugu Mori，協同Druckenmiller和Erickson對這些骸骨的構造進行了詳盡的分析，以作為他博士論文的一部分。

Their work revealed that the Ugrunaaluk kuukpikensis is most closely related to Edmontosaurus, another type of duck-billed dinosaur that lived roughly 70 million years ago in Alberta, Montana and South Dakota.

他們的研究成果顯示Ugrunaaluk kuukpikensis最近的親戚為埃德蒙頓龍(Edmontosaurus)。這是另外一種鴨嘴龍，生活於7000萬年前左右的亞伯達省、蒙大拿州和南達科他州。

But, the combination of features found in these skeletons were not present in Edmontosaurus or in any other species of duck-billed dinosaurs.

然而，這些骸骨中所具備的特徵組合，並未在埃德蒙頓龍或其他任何一種鴨嘴龍身上發現。

In particular, researchers observed that the Ugrunaaluk kuukpikensis had very unique skeletal structures in the area of the skull, especially around the mouth.

重要的是研究人員觀察到Ugrunaaluk kuukpikensis具有相當獨樹一格的頭骨構造，尤其是口部四周。

"Because many of the bones from our Alaskan species were from younger individuals, a challenge of this study was figuring out if the differences with other hadrosaurs was just because they were young, or if they were really a different species," Druckenmiller said. "Fortunately, we also had bones from older animals that helped us realize Ugrunaaluk was a totally new animal."

「由於我們在阿拉斯加找到的這個物種有許多骨骸是來自青少年個體，本研究的挑戰之一便是要找出牠們與其他鴨嘴龍的差異是否只是因為牠們比較年幼，或者這真的是一種全新物種。」Druckenmiller說，「幸運的是，我們有發現一些來自較為成熟個體的骨骸，有助於我們確認Ugrunaaluk真的是一種全新的動物。」

Druckenmiller worked with an instructor of the Iñupiaq language at the Alaska Native Language Center at University of Alaska Fairbanks to develop a name for the new species that was culturally, anatomically and geographically correct. They wanted to pay tribute to the local tribes who live near the research site.

Druckenmiller與阿拉斯加原住民語言中心(位於阿拉斯加大學費爾班克斯分校)的伊努必語講師合作，確保此新物種的命名在文化、解剖學和地理上都有其意義。他們想要以此對居住在挖掘場址附近的當地部落獻上感激之意。

Erickson and Druckenmiller will continue to mine the Prince Creek Formation for additional skeletons. However, accessing the field site is extremely difficult. Besides the frigid weather, they have to use bush planes that are capable of landing on gravel bars and inflatable boats to access the sites, and often have to repel down the side of a cliff to do the digging.

Erickson和Druckenmiller將會繼續挖掘Prince Creek組以得到更多具骸骨。然而，要到達這處野外場址並非易事，他們必須要利用能夠降落在礫石河岸上的小飛機和充氣船才能抵達場址，且經常要懸掛在懸崖峭壁上進行挖掘工作。

The area is rich with animal skeletons, and they estimate there are at least 13 different species of dinosaur present based on teeth and other remains, plus birds, small mammals and some fish.

這個區域的動物骨骸種類十分豐富，根據牙齒種類，他們判斷這裡至少還有13種恐龍，而其他的動物種類包括了鳥類、小型哺乳類和一些魚類。

They will also delve deeper into how these animals lived and functioned in conditions not typically thought to be amenable to occupation by reptilian dinosaurs.

在這種不符合一般認為會有恐龍居住的環境中，這些動物的生活方式與生理活動會是如何，也是他們將繼續深入探討的課題。

"Alaska is basically the last frontier," said Erickson, who is originally from Alaska. "It's virtually unexplored in terms of vertebrate paleontology. So, we think we're going to find a lot of new species."

「基本上阿拉斯加是最後的邊疆地帶，」Erickson說，他本身便是阿拉斯加出身。「在古脊椎生物學中，它是仍未被探索過的處女地。因此，我們認為我們將會在那裡發現許多新的生物。」

Three full skeletons of Ugrunaaluk kuukpikensis will be on display at the University of Alaska Museum of the North as well as a new painting of the species by Alaskan artist James Havens.

阿拉斯加大學博物館將會展出三組Ugrunaaluk kuukpikensis的完整頭骨，和由阿拉斯加藝術家James Havens繪製的這些物種的復原圖。

This research was supported by the National Science Foundation and the Department of Interior's Bureau of Land Management. The research is also the primary subject of the doctoral thesis completed by Druckenmiller's former graduate student Hirotsugu Mori, who is now a curator for the Saikai City Board of Education in Japan.

本研究由美國國家科學基金會與美國內政部土地管理署資助。此篇研究也為Hirotsugu Mori 的博士論文主旨，他目前為日本西海市教育委員會的主任，之前則在Druckenmiller的實驗室攻讀碩士。

引用自：Florida State University. "‘Lost world’ of cold weather dinosaurs discovered." ScienceDaily. ScienceDaily, 22 September 2015.