多国考古学家日前通过研究发现，在中国东北部生活过的恐龙曾经遭遇严寒天气，这也解释了为什么它们身上都长有羽毛。
这项研究汇集了法国、中国、日本和泰国多家机构的考古专家。研究人员在最新一期美国《国家科学院学报》上报告说，恐龙大多生活在中生代，这一时期全球气候比较炎热，人们由此推测，恐龙的生存环境温度较高。不过该研究小组却提出了相反的意见。他们在中国辽西热河生物群所在地展开工作，这里曾先后发现中华龙鸟、尾羽龙和小盗龙等多种“带毛恐龙”，其生存的年代大约在1.25亿到1.1亿年前。由于它们并不会飞，因此部分科学家猜测，羽毛的作用可能是御寒。
为了证实上述假设，考古学家开始设法确定当时的温度。最终，他们通过测定雨水中的氧同位素含量，发现这一时期与当前中国北方地区的气温十分相近，到了冬天，各种生物都要经历严寒的考验，乌龟、蜥蜴等冷血动物选择冬眠，而哺乳动物、鸟类和恐龙只能依靠自身的羽翼和皮毛维持生存，这也解释了为什么这一地区发现的恐龙化石伴有羽毛。
科学家们表示，上述成果能够帮助人们了解这一地区恐龙的生活环境，从而对它们的习性和特点进行深入研究。（生物谷Bioon.com）
生物谷推荐原文出处：
PNAS doi: 10.1073/pnas.1011369108
Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates
Romain Amiota,1,2, Xu Wangb, Zhonghe Zhoua, Xiaolin Wanga, Eric Buffetautc, Christophe Lécuyerd,2, Zhongli Dingb, Frédéric Fluteaue, Tsuyoshi Hibinof, Nao Kusuhashig, Jinyou Moh, Varavudh Suteethorni, Yuanqing Wanga, Xing Xua, and Fusong Zhangb
Abstract
Early Cretaceous vertebrate assemblages from East Asia and particularly the Jehol Biota of northeastern China flourished during a period of highly debated climatic history. While the unique characters of these continental faunas have been the subject of various speculations about their biogeographic history, little attention has been paid to their possible climatic causes. Here we address this question using the oxygen isotope composition of apatite phosphate (δ) from various reptile remains recovered from China, Thailand, and Japan. δ values indicate that cold terrestrial climates prevailed at least in this part of Asia during the Barremian—early Albian interval. Estimated mean air temperatures of about 10 ± 4 °C at midlatitudes (～42 °N) correspond to present day cool temperate climatic conditions. Such low temperatures are in agreement with previous reports of cold marine temperatures during this part of the Early Cretaceous, as well as with the widespread occurrence of the temperate fossil wood genus Xenoxylon and the absence of thermophilic reptiles such as crocodilians in northeastern China. The unique character of the Jehol Biota is thus not only the result of its evolutionary and biogeographical history but is also due to rather cold local climatic conditions linked to the paleolatitudinal position of northeastern China and global icehouse climates that prevailed during this part of the Early Cretaceous.
