據(jù)美國(guó)物理學(xué)家組織網(wǎng)近日?qǐng)?bào)道,，古生物學(xué)家在澳大利亞維多利亞州沿岸發(fā)現(xiàn)了20多個(gè)極地恐龍的足跡,，這為窺見(jiàn)約1.5億年前全球變暖期間的動(dòng)物習(xí)性提供了極珍貴的根據(jù)。
維多利亞海岸是澳大利亞洲和南極洲曾經(jīng)相連的地方，它的早白堊紀(jì)地層是世界上極地恐龍骨骼的最好記錄組合地。研究人員在米拉奧西奧海灘（音譯）發(fā)現(xiàn)了恐龍的足跡。這一區(qū)域是崎嶇的海岸峭壁區(qū),，由數(shù)百萬(wàn)年所累積的沉淀圖層構(gòu)成，經(jīng)斷裂,、波浪侵襲和風(fēng)蝕,，露出了大塊大塊的巖石，其中就藏有恐龍足跡,。
兩塊早白堊世時(shí)期的砂巖保留了三趾足跡,。它們似乎屬于三個(gè)不同大小的小型獸腳類肉食恐龍?jiān)谙募玖粝碌摹?/p>
埃默里大學(xué)古生物學(xué)家安東尼·馬丁于2010年6月14日正午左右在維多利亞州發(fā)現(xiàn)了恐龍的第一批足跡：波痕和蹤跡化石，它們貌似是在一堆墜石中挖掘所致,。這一塊砂巖有15處足跡,，包括三個(gè)最小的獸腳類恐龍的連續(xù)性足跡。“這些波紋和洞穴表明這里是最有可能發(fā)現(xiàn)極地恐龍足跡的區(qū)域,。”馬丁說(shuō),。
第二塊含有足跡的石塊在三個(gè)小時(shí)后由當(dāng)?shù)匾幻驹刚吒窭赘?middot;丹尼發(fā)現(xiàn)。這個(gè)石塊和第一塊有相似的特征,，有8個(gè)足跡,。這些足跡表明，這群獸腳類恐龍大小不一,，有的小如小雞,，也有的大如巨型起重機(jī)。
“這兩塊巖石來(lái)自于恐龍所行走的同一巖層和同一地面,，”馬丁說(shuō)，“這些足跡直接指引了關(guān)于在地質(zhì)史的這一重要時(shí)段這些恐龍如何與兩極的生態(tài)系統(tǒng)相互作用的研究,。”
2006年2月,，馬丁在維多利亞的一片沿岸區(qū)發(fā)現(xiàn)了第一個(gè)肉食性恐龍的足跡,。同年5月，在另一片臨近米拉奧西奧海灘的偏遠(yuǎn)地區(qū),，他發(fā)現(xiàn)了在澳大利亞的第一個(gè)恐龍洞穴遺址化石,，這個(gè)發(fā)現(xiàn)緊隨馬丁在美國(guó)蒙大拿州發(fā)現(xiàn)的第一個(gè)恐龍洞穴和掘穴恐龍之后。這兩大發(fā)現(xiàn)表明,，掘穴行為是白堊紀(jì)時(shí)上百萬(wàn)年的生存期中不同半球的不同種類恐龍的共性,。
這一發(fā)現(xiàn)刊載在《開(kāi)天辟地：澳大拉西亞古生物學(xué)期刊》上，是迄今為止關(guān)于南半球所發(fā)現(xiàn)的恐龍足跡的最大,、最好的采集和研究發(fā)現(xiàn),。該研究小組成員還包括維多利亞博物館的托馬斯·里奇、莫納什大學(xué)的邁克爾·霍爾和帕特麗夏·威格士·里奇以及埃默里大學(xué)的貢薩洛·瓦茲奎茲·普羅科佩茨,。（生物谷 Bioon.com）
doi:10.1080/03115518.2011.597564
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A polar dinosaur-track assemblage from the Eumeralla Formation (Albian), Victoria, Australia
Anthony J. Martinac*, Thomas H. Richb, Michael Hallc, Patricia Vickers-Richc & Gonzalo Vazquez-Prokopeca
The Eumeralla Formation (Aptian–Albian) of the Otway Group in Victoria, Australia, has yielded a significant amount of dinosaur skeletal material since the late 1970s, which, when combined with finds from the Wonthaggi Formation (Aptian) of the upper Strzelecki Group, constitute the best-documented polar-dinosaur assemblage in the Southern Hemisphere. In contrast, dinosaur tracks have barely augmented this body fossil record; up to now, only one ornithopod track had been documented in any detail from the Otway Group. In this study, we report a new find of at least 24 dinosaur tracks preserved on two ripple-bedded sandstone blocks of the Eumeralla Formation, discovered at Milanesia Beach, Victoria. This dinosaur-track assemblage is the best in terms of numbers and quality found thus far in formerly polar environments of the Southern Hemisphere. One block includes the first known dinosaur trackway from the Cretaceous of Victoria, consisting of three consecutive footprints made by a small theropod. The assemblage indicates three differently sized theropods, thus providing new insights on dinosaur diversity and activity not indicated previously by body fossils in the Eumeralla Formation. Tracks are preserved in fluvial floodplain deposits and were possibly imprinted on emergent floodplain surfaces following seasonal flooding during a polar summer. The abundant tracks at this site suggest more such finds are likely in floodplain deposits of the Otway Group, although behavioural and preservational conditions unique to polar environments may have limited their formation.
