“燕子去了,，有再來的時候”,，這個描寫候鳥遷徙的句子如果放到一億多年前的侏羅紀，也許要改成“恐龍去了,，有再來的時候”,，因為研究人員最近發(fā)現(xiàn)了恐龍也會進行季節(jié)性遷徙的有力證據(jù)。
英國《自然》雜志網(wǎng)站10月26日刊登一份報告說,，包括恐龍在內(nèi)的脊椎動物牙齒生長時,，都會帶有當時所在地區(qū)氧同位素比例特征。美國科羅拉多學院的研究人員對蜥腳類恐龍牙齒化石進行相關分析后發(fā)現(xiàn),，這種恐龍很可能會進行季節(jié)性遷徙,。研究人員推測，這些恐龍經(jīng)常到谷地肥沃的沖積平原中覓食,，但當谷地遭受季節(jié)性干旱時,，就遷徙到高地，等旱季過后再回到谷地,。
研究人員亨利·弗里克說,，這個結(jié)果是意料之中的，因為蜥腳類恐龍體型巨大,，又是食草動物,，如果長期在一個地方居住，當?shù)刂脖浑y以承受,。
蜥腳類恐龍是已知陸地上曾有過的最大的脊椎動物之一,，據(jù)化石推測其體長可達30多米，估計體重可達上百噸,。這種恐龍的季節(jié)性遷徙為了解它們的生活習性提供了線索,。研究人員說,，今后將嘗試用類似技術手段來研究其他種類恐龍的生活習性。(生物谷 Bioon.com)
doi:10.1038/nature10570
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Lowland–upland migration of sauropod dinosaurs during the Late Jurassic epoch
Henry C. Fricke, Justin Hencecroth1 & Marie E. Hoerner
Sauropod dinosaurs were the largest vertebrates ever to walk the Earth, and as mega-herbivores they were important parts of terrestrial ecosystems. In the Late Jurassic-aged Morrison depositional basin of western North America, these animals occupied lowland river-floodplain settings characterized by a seasonally dry climate. Massive herbivores with high nutritional and water needs could periodically experience nutritional and water stress under these conditions, and thus the common occurrence of sauropods in this basin has remained a paradox. Energetic arguments and mammalian analogues have been used to suggest that migration allowed sauropods access to food and water resources over a wide region or during times of drought or both, but there has been no direct support for these hypotheses. Here we compare oxygen isotope ratios (δ18O) of tooth-enamel carbonate from the sauropod Camarasaurus with those of ancient soil, lake and wetland (that is, ‘authigenic’) carbonates that formed in lowland settings. We demonstrate that certain populations of these animals did in fact undertake seasonal migrations of several hundred kilometres from lowland to upland environments. This ability to describe patterns of sauropod movement will help to elucidate the role that migration played in the ecology and evolution of gigantism of these and associated dinosaurs.
