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Isotopes in East Asian dinosaur teeth indicate environment and ecology



Ben Creisler
bcreisler@gmail.com

A new online paper:


Romain Amiot, Xu Wang, Zhonghe Zhou, Xiaolin Wang, Christophe Lécuyer,
Eric Buffetaut, Frédéric Fluteau, Zhongli Ding, Nao Kusuhashi, Jinyou
Mo, Marc Philippe, Varavudh Suteethorn, Yuanqing Wang & Xing Xu (2014)
Environment and ecology of East Asian dinosaurs during the Early
Cretaceous inferred from stable oxygen and carbon isotopes in apatite.
Journal of Asian Earth Sciences (advance online publication)
doi:10.1016/j.jseaes.2014.11.032
http://www.sciencedirect.com/science/article/pii/S1367912014005628


Highlights

We analyzed carbon and oxygen isotope compositions of dinosaur teeth
from East Asia.
Stable isotope compositions were interpreted in terms of environmental
conditions.
During the Early Cretaceous, East Asia was characterized by contrasted
environments.
These environments may have acted as cradles of evolution for Late
Cretaceous taxa.


Abstract

During the cold Late Barremian – Early Albian interval, terrestrial
environments in East Asia were populated by rich and diverse
vertebrate faunas characterized by a strong provincialism. The
latitudinal gradient of temperature and the existence of geographic
barriers likely accounted for some aspects of this heterogeneous
distribution of faunas. Other factors, however, such as local
environmental conditions and interactions within vertebrate
communities, which could have influenced their distribution, have not
yet been fully identified and understood. Therefore, new and published
oxygen and carbon isotope compositions of apatite from Chinese and
Thai reptiles (dinosaurs, crocodilians and turtles) have been analyzed
and interpreted in terms of ecology, local air temperature and
precipitation amounts. Differences in carbon and oxygen isotope
compositions between various groups of sympatric plant-eating
dinosaurs (sauropods, ornithopods and ceratopsians) indicate food
resources partitioning among them most likely to avoid competition.
Mid-latitude environments, where the Jehol biota flourished, were
submitted to cool temperate climatic conditions with Mean Air
Temperature (MAT) of 10±4°C and Mean Annual Precipitations (MAP) of
about 600 mm/yr compatible with the existence of forest environments.
By contrast, sub-tropical regions, characterized by MAT of about
20-25°C were either submitted to high amounts of seasonal
precipitations (of about 1200mm/yr in Thailand) or to significant
aridity (MAP of about 400 mm/yr in South China). This difference in
precipitation regime between Thailand and South China may be
attributed to the occurrence of the Coastal Cordillera extending along
the East margin of the South China block. These mountain ranges likely
prevented humid air masses from the Pacific to penetrate some parts of
South China, thus generating a “rain shadow effect”. Mosaic
environments characterizing East Asia during the Late Early Cretaceous
may have acted as a cradle for the origination of advanced dinosaur
taxa that subsequently radiated over Eurasia and North America during
the Late Cretaceous.