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Re: Cold winters for Jehol dinosaurs during Early Cretaceous explain feathers?



From: Ben Creisler
bh480@scn.org

Here's the official abstract:

Romain Amiot, Xu Wang, Zhonghe Zhou, Xiaolin Wang, Eric Buffetaut,
Christophe Lécuyer, Zhongli Ding, Frédéric Fluteau, Tsuyoshi Hibino, Nao
Kusuhashi, Jinyou Mo, Varavudh Suteethorn, Yuanqing Wang, Xing Xu, and
Fusong Zhang (2011)
Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early
Cretaceous climates.
Proceedings of the National Academy of Sciences
Published online before print March 10, 2011,
doi: 10.1073/pnas.1011369108 
http://www.pnas.org/content/early/2011/03/09/1011369108.abstract


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 (delta 18 O p) from various reptile
remains recovered from China, Thailand, and Japan. delta 18 O p  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. 


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