美國西伊利諾伊大學(xué)（Western Illinois University）的古生物學(xué)家M.Bonnan介紹說：“科學(xué)家們長期以來都認(rèn)為大型蜥腳類恐龍（sauropod）在旱季時需要經(jīng)過長距離跋涉才能尋找到食物來源,。”明尼蘇達(dá)州麥克萊斯特學(xué)院（Macalester College in Minnesota）的古生物教授K.Curry Rogers則說道：“此次新的發(fā)現(xiàn)也進(jìn)一步證實(shí)了過去的推論,。”
Rogers所說新的發(fā)現(xiàn)指的是科羅拉多大學(xué)（Colorado College）地質(zhì)學(xué)家H.Fricke最近所研究的32顆蜥腳類恐龍牙齒化石,，相關(guān)的研究成果已在著名的科學(xué)雜志《自然》上發(fā)表,。
這32顆牙齒來自于美國恐龍化石資源豐富的懷俄明州（Wyoming）和猶他州（Utah）,，時代可追溯到距今1.5億年前的晚侏羅世時期（late Jurassic）,。蜥腳類恐龍是所有陸生脊椎動物中最巨大的,，頭小，頸部和尾部較長,，四肢粗壯,，四足行走，主要以植物為食,。最大的蜥腳類恐龍?bào)w重可達(dá)100噸,，體長120英尺（約36.5米），此次所研究的蜥腳類恐龍?bào)w型較小,，體長約60英尺,，體重約25噸。
通過比較分析恐龍牙齒琺瑯質(zhì)（牙冠表層的半透明白色硬組織,，十分堅(jiān)硬）和古沉積物中所保存的氧元素化學(xué)信息,，科學(xué)家們可以了解這些史前巨獸的飲用水從何處獲得。不一致的化學(xué)分析結(jié)果表明：這種史前巨獸必須要行走數(shù)百公里以上才能從平原地區(qū)來達(dá)高地地區(qū)找到珍貴的食物和水資源,。
Fricke還說道：“蜥腳類恐龍的這種長途遷徙與季節(jié)變化有關(guān),，在夏季，它們要經(jīng)歷五個月的長途跋涉才能來到高海拔的高山地區(qū),，而在冬季又要再次返回——它就像一臺完美的運(yùn)動機(jī)器,。”
而在氣候濕潤植物茂盛的時候，蜥腳類恐龍的食譜包括了當(dāng)時的各類植物——蕨類,、木賊類,、松柏類和苔蘚類植物，你可以想象它那龐大的身軀每頓的進(jìn)食量也將會是十分驚人的,。（生物谷 Bioon）
doi:10.1038/nature10570
PMC:
PMID:
Lowland–upland migration of sauropod dinosaurs during the Late Jurassic epoch
Henry C. Fricke, Justin Hencecroth & 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 climate1, 2. 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 both3, 4, 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.
