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Sauropod migration in Nature



From: Ben Creisler
bh480@scn.org

On the Nature online site:


News article:
http://www.nature.com/news/2011/111025/full/news.2011.612.html

Research article:

Henry C. Fricke, Justin Hencecroth & Marie E. Hoerner (2011)
Lowland?upland migration of sauropod dinosaurs during the Late Jurassic
epoch.
Nature (advance online publication)
doi:10.1038/nature10570 
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature10570.html

Sauropod dinosaurs were the largest vertebrates ever to walk the Earth, and
as mega-herbivores they were important parts of terrestrial ecosystems. In
the Late Jurassic-aged Morrison depositional basin of western North
America, these animals occupied lowland river-floodplain settings
characterized by a seasonally dry climate. Massive herbivores with high
nutritional and water needs could periodically experience nutritional and
water stress under these conditions, and thus the common occurrence of
sauropods in this basin has remained a paradox. Energetic arguments and
mammalian analogues have been used to suggest that migration allowed
sauropods access to food and water resources over a wide region or during
times of drought or both, but there has been no direct support for these
hypotheses. Here we compare oxygen isotope ratios (delta18O) of
tooth-enamel carbonate from the sauropod Camarasaurus with those of ancient
soil, lake and wetland (that is, 'authigenic') carbonates that formed in
lowland settings. We demonstrate that certain populations of these animals
did in fact undertake seasonal migrations of several hundred kilometres
from lowland to upland environments. This ability to describe patterns of
sauropod movement will help to elucidate the role that migration played in
the ecology and evolution of gigantism of these and associated dinosaurs.



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