The Korea Herald


Teeth study shows big dinosaurs trekked for food


Published : Oct. 28, 2011 - 09:41

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LOS ANGELES (AP) — What did giant plant-munching dinosaurs do when they couldn't find enough to eat in the parched American West? They hit the road. An analysis of fossilized teeth adds further evidence that the long-necked dinosaurs called sauropods — the largest land creatures — went on road trips to fill their gargantuan appetites.

Scientists have long theorized that sauropods foraged for precious resources during droughts because of their preserved tracks and long limbs that were "ideal moving machines" and allowed them to cover long distances, said paleobiologist Matthew Bonnan of Western Illinois University.

The latest study is the best evidence yet that at least one kind of sauropod "took to the hills in search of food when times got tough in the lowlands," said paleontologist Kristi Curry Rogers at Macalester College in Minnesota.

The new work, published online Wednesday by the journal Nature, was led by geologist Henry Fricke of Colorado College.

The researchers analyzed 32 sauropod teeth collected in Wyoming and Utah. The teeth came from massive plant-eaters that roamed a semi-arid basin in the American West during the late Jurassic period about 150 million years ago.

The largest sauropods weighed 100 tons and were 120 feet long. The type in the study was smaller — about 60 feet in length and weighing 25 tons.

Scientists can get a glimpse into the source of the dinosaurs' drinking water by comparing the oxygen preserved in the tooth enamel to that found in ancient sediment.

A chemical analysis showed differences in the teeth and the basin where the dinosaurs were buried, meaning they must have wandered hundreds of miles from the flood plains to the highlands for food and water.

Fricke said the movement appeared to be tied to changing seasons. Sauropods left the basin in the summer for higher elevations — a trek that took about five months — and returned in the winter.

In lush times, sauropods would have feasted on a diversity of plants including ferns, horsetails, conifers and moss, said John Foster, a curator at the Museum of Western Colorado, who had no part in the research.



초식 공룡, 철새처럼 이동했다

지구 역사상에서 가장 거대했던 공룡이 철새처럼  먹이를 찾아 계절마다 수 백㎞를 이동했다는 연구 결과가 나왔다.

미국 콜로라도 대학의 헨리 프리케 지질학과장이 이끄는 연구진은 미 서부 와이 오밍 주의 서모폴리스에서 발견된 초식 공룡 사우로포드 치아 화석의 에나멜질과 이 지역의 퇴적물 속에서 발견된 에나멜질의 산소 동위원소를 비교 분석한 결과 사우로 포드가 건조한 여름에는 고지대로 이동했다가 습한 겨울에 분지로 돌아왔을  것이라 고 결론 내렸다.

연구진은 동위원소를 분석하면 공룡이 살던 환경의 건조상태와 고도 등을 알 수 있는데 공룡 치아와 퇴적물의 동위원소 비율이 다르게 나타나 공룡들이 주서식지인 습한 분지를 떠난 적이 있었던 게 분명하다고 밝혔다.

연구진에 따르면 1억 5천만여년 전인 쥐라기 후기에 살았던 사우로포드는 5-6개 월에 걸쳐 300km를 이동해 고지대로 올라갔다가 다시 분지로 돌아왔다.

연구진은 이동하는 것이 사우로포드의 고유한 습성인지, 아니면 이 지역의 사우 로포드만 환경적 스트레스에 대응해 이동했던 것인지 확인하기 위해서는 다른  지역 의 사우로포드에 대한 연구가 필요하다고 덧붙였다.