根据一项新的研究结果显示，大多数恐龙可能并非如同人们在电影中看到的那种可怕食肉动物，而是一群“素食主义者”。相当一部分兽脚类恐龙是用两条腿走路，还长有羽毛，比起肉食它们宁愿吃树叶和草。
据国外媒体报道，科学家通过分析90多种兽脚类恐龙的饮食结构后发现，食用植物的恐龙比例非常惊人。科学家现在相信，诸如《侏罗纪公园》等电影作品中的霸王龙和迅猛龙这样的肉食恐龙，只是当时自然界中的“特例”。
这一研究发现对传统观点发出了挑战，传统观点认为几乎所有的兽脚类恐龙都是靠捕猎生存的。领导该项研究的是美国芝加哥菲尔德博物馆的林赛-扎诺(Lindsay Zanno)博士表示，那些与鸟类相关的兽脚类恐龙可能并非靠猎食生存。
研究恐龙的饮食并不容易，一些如霸王龙类的牙齿当然明显是肉食动物，三角龙的牙齿结构显然更适应切割植物，但是更多的恐龙牙齿特征很模糊相当难以分辨。此外科学家还根据其他线索，如粪便化石，胃部遗留物和齿痕等来分析它们的饮食结构。
在研究中，科学家共发现了24种与植物性饮食有关的解剖学特征，包括无牙和如鸟类一般喙部的特征，科学家们认为有这些“证据”的恐龙可以假设为素食者。一种观点认为，兽脚类恐龙为了适应板块漂移带来的环境变化，进化成为了杂食性动物，那些食用更多植物的恐龙牙齿逐渐退化，由像鸟类一般的喙部和较长颈部所替代。
扎诺博士称：“这项研究证实了我们之前的设想，是时候重新认识一下这些恐龙的进化历程了。”目前，关于有羽毛的恐龙是如何进化为鸟类还是一个谜。扎诺补充道：“我们还不清楚是什么原因驱使鸟类的祖先开始飞向空中，想在树上寻找食物只是众多的可能性之一。”这项研究已经发表在《美国科学院院刊》中。（生物谷Bioon.com）
生物谷推荐原文出处：
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.
