根據(jù)一項新的研究結(jié)果顯示,，大多數(shù)恐龍可能并非如同人們在電影中看到的那種可怕食肉動物,，而是一群“素食主義者”,。相當(dāng)一部分獸腳類恐龍是用兩條腿走路,，還長有羽毛,，比起肉食它們寧愿吃樹葉和草。
據(jù)國外媒體報道,，科學(xué)家通過分析90多種獸腳類恐龍的飲食結(jié)構(gòu)后發(fā)現(xiàn),，食用植物的恐龍比例非常驚人。科學(xué)家現(xiàn)在相信,，諸如《侏羅紀(jì)公園》等電影作品中的霸王龍和迅猛龍這樣的肉食恐龍,，只是當(dāng)時自然界中的“特例”。
這一研究發(fā)現(xiàn)對傳統(tǒng)觀點發(fā)出了挑戰(zhàn),，傳統(tǒng)觀點認(rèn)為幾乎所有的獸腳類恐龍都是靠捕獵生存的,。領(lǐng)導(dǎo)該項研究的是美國芝加哥菲爾德博物館的林賽-扎諾(Lindsay Zanno)博士表示，那些與鳥類相關(guān)的獸腳類恐龍可能并非靠獵食生存,。
研究恐龍的飲食并不容易,，一些如霸王龍類的牙齒當(dāng)然明顯是肉食動物，三角龍的牙齒結(jié)構(gòu)顯然更適應(yīng)切割植物,，但是更多的恐龍牙齒特征很模糊相當(dāng)難以分辨,。此外科學(xué)家還根據(jù)其他線索，如糞便化石,，胃部遺留物和齒痕等來分析它們的飲食結(jié)構(gòu)。
在研究中,，科學(xué)家共發(fā)現(xiàn)了24種與植物性飲食有關(guān)的解剖學(xué)特征,，包括無牙和如鳥類一般喙部的特征，科學(xué)家們認(rèn)為有這些“證據(jù)”的恐龍可以假設(shè)為素食者,。一種觀點認(rèn)為,，獸腳類恐龍為了適應(yīng)板塊漂移帶來的環(huán)境變化，進化成為了雜食性動物,，那些食用更多植物的恐龍牙齒逐漸退化,，由像鳥類一般的喙部和較長頸部所替代。
扎諾博士稱：“這項研究證實了我們之前的設(shè)想,，是時候重新認(rèn)識一下這些恐龍的進化歷程了,。”目前，關(guān)于有羽毛的恐龍是如何進化為鳥類還是一個謎,。扎諾補充道：“我們還不清楚是什么原因驅(qū)使鳥類的祖先開始飛向空中,，想在樹上尋找食物只是眾多的可能性之一。”這項研究已經(jīng)發(fā)表在《美國科學(xué)院院刊》中,。（生物谷Bioon.com）
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.1011924108
Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution
Lindsay E. Zanno1 and Peter J. Makovicky
Abstract
Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs—a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet.
