加拿大在北極地區發現鴨嘴龍化石

加拿大一古生物學家４日說，此前在加拿大北部努納武特地區發現的一具鴨嘴龍化石，可能是迄今人類在地球最北的地方發現的恐龍化石。

    研究這具恐龍化石的古生物學家馬修‧瓦夫雷克當天在接受加拿大廣播公司採訪時說，這一鴨嘴龍脊椎化石發現于努納武特地區阿克塞爾‧海伯格島，位于北緯７５度左右，距離人類最北的永久居住點以北５００公裏。相關研究成果發表在最新的《北極》雜志上。

    鴨嘴龍屬草食恐龍。瓦夫雷克說，從已發現的脊椎化石推斷這只鴨嘴龍身長約８米，在北極高緯度地區的這一發現實屬“罕見”。他指出，這類北極鴨嘴龍生活在１億年前至６６００萬年前的白堊紀晚期，當時的島嶼生活環境與北美大陸分離，這意味著它們在冬季不可能往南遷移。由于北美大陸漂移，那時候阿克塞爾‧海伯格島應位于當今位置稍往南，但仍位于北極圈之內。

    位于北極圈以南的加拿大阿爾伯塔省近年來發現多具恐龍化石，瓦夫雷克是阿爾伯塔省大草原區恐龍博物館的首席古生物學家。他認為，這一發現有助于界定恐龍曾經生活的實際區域。當時北極地區平均氣溫比現在高出１５攝氏度，該地區恐龍所處生活環境遠不如當今極端，不過當時北極地區也有夏日２４小時極晝和冬日２４小時極夜。因此，冬季可供鴨嘴龍食用的植物並不多。

    瓦夫雷克指出，加拿大北極地區和美國阿拉斯加州北斯洛普地區類似，都存在大量恐龍化石有待發掘，但因地質條件、地理位置及交通原因，加拿大北極地區的恐龍化石發掘工作遠遠滯後。





Nunavut dinosaur fossil is most northern ever found

Hadrosaurs were plant-eating, duck-billed dinosaurs that lived during the Cretaceous period

A dinosaur fossil from the Canadian High Arctic is the most northern ever discovered.

The fossil vertebra, part of the backbone of a duck-billed dinosaur called a hadrosaur, was discovered on Axel Heiberg Island in Nunavut at a latitude of about 75 degrees north – 500 kilometres further north than any permanent human settlement, said paleontologist Matthew Vavrek, lead author of a new paper describing the fossil. The paper was published in the journal Arctic.

Hadrosaurs are a group of plant-eating dinosaurs, including Edmontosaurus, with duck-like bills and sometimes crests on their head. The size of the Arctic bone suggests that it was from a hadrosaur about eight-metres long.

"This find up in the High Arctic is kind of unique because we found it on what at the time was kind of a relatively isolated part of North America. These animals would have been living in this area year round," said Vavrek in an interview that airs Saturday on CBC's Quirks & Quarks.

During the late Cretaceous period about 100 to 66 million years ago, when the Arctic hadrosaur lived, he added, its home was part of an island separated from the rest of North America by two seas, running from the Arctic Ocean to the Gulf of Mexico, and one cutting through northern Saskatchwan and Manitoba.

The fossil vertebra, part of the backbone of a duck-billed dinosaur called a hadrosaur, was discovered on Axel Heiberg Island in Nunavut.

 

That means it couldn't have migrated south during the winter.

Vavrek, curator and head paleontologist at the Philip J. Currie Dinosaur Museum in Grand Prairie, Alta., said the discovery helps show the true range of where dinosaurs once lived.

During the Late Cretaceous, North America was rotated such that Axel Heiberg Island was a little further south than it is now but still above the Arctic Circle.

Temperatures averaged 15 degrees warmer and were far less extreme than they are in the region today. However, the Arctic still featured 24 hours of sunlight at the height of summer and 24 hours of darkness at the winter solstice.

Because of that, there wouldn't have been a lot of plants to eat in the winter.

Vavrek suggests that the Arctic hadrosaur survived by eating some of the things found in the stomachs and fossilized feces of hadrosaurs that lived further south, such as twigs and branches, and decaying wood that contained nutritious fungi.

"These dinosaurs definitely could have survived up in that area year round, living on this low-grade plant matter."

Vavrek said paleontologists have barely looked for dinosaur fossils in the Canadian High Arctic because it's so expensive and logistically difficult to get there, and because the permafrost tends to break up fossil skeletons as it churns through its freeze-thaw cycles. But he thinks there may still remain many dinosaurs left to be found there.