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Environmental fluctuations and dinosaur dominance
Climate and plant community instability may have hampered the success of dinosaurs in
tropical latitudes during the Triassic Period, according to a study. Although dinosaurs
ecologically dominated high latitudes before the end of the Triassic, they were rare in tropical
latitudes, with few species present, for up to 30 million years after their origin. To investigate
the environment in tropical latitudes during the late Triassic, Jessica H. Whiteside and
colleagues examined the sedimentary record preserved in the Chinle Formation in northern
New Mexico. The authors found that the flora within the formation displayed a change from a
seed fern-dominated system to a conifer-dominated system, and that individual plant groups
repeatedly alternated from rare to common through time. Carbon isotope data from fossil
organic matter within the formation suggest an environment affected by strong fluctuations
between humid and arid conditions. Widespread fossil charcoal material suggests frequent
wildfires during the Triassic, possibly due to environmental fluctuation that encouraged
organic matter growth during humid periods and enhanced moisture loss during arid times.
The results suggest that the fluctuations, associated with high atmospheric CO2, may have
prevented widespread establishment of large dinosaur species in tropical latitudes due to
unpredictable resource availability, according to the authors.
Article #15-05252: “Extreme ecosystem instability suppressed tropical dinosaur dominance
for 30 million years,” by Jessica H. Whiteside et al.
MEDIA CONTACT: Jessica H. Whiteside, Ocean and Earth Science, University of
Southampton, UNITED KINGDOM; tel: 011442380593199; e-mail:
<J.Whiteside@soton.ac.uk>
Images accompanying this article are available.
http://www.eurekalert.org/jrnls/pnas/15-05252.htm
AFTER THIS ARTICLE PUBLISHES, it will be available at
http://www.pnas.org/cgi/doi/10.1073/pnas.1505252112