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Decompression syndrome in ichthyosaurs



From: Ben Creisler
bcreisler@gmail.com


A new online paper:



B. M. Rothschild, Z. Xiaoting and L. D. Martin (2012)
Adaptations for marine habitat and the effect of Triassic and Jurassic
predator pressure on development of decompression syndrome in
ichthyosaurs.
Naturwissenschaften (advance online publication)
DOI: 10.1007/s00114-012-0918-0
http://www.springerlink.com/content/q498172437420366/


Decompression syndrome (caisson disease or the “the bends”) resulting
in avascular necrosis has been documented in mosasaurs,
sauropterygians, ichthyosaurs, and turtles from the Middle Jurassic to
Late Cretaceous, but it was unclear that this disease occurred as far
back as the Triassic. We have examined a large Triassic sample of
ichthyosaurs and compared it with an equally large post-Triassic
sample. Avascular necrosis was observed in over 15 % of Late Middle
Jurassic to Cretaceous ichthyosaurs with the highest occurrence (18 %)
in the Early Cretaceous, but was rare or absent in geologically older
specimens. Triassic reptiles that dive were either physiologically
protected, or rapid changes of their position in the water column rare
and insignificant enough to prevent being recorded in the skeleton.
Emergency surfacing due to a threat from an underwater predator may be
the most important cause of avascular necrosis for air-breathing
divers, with relative frequency of such events documented in the
skeleton. Diving in the Triassic appears to have been a “leisurely”
behavior until the evolution of large predators in the Late Jurassic
that forced sudden depth alterations contributed to a higher
occurrence of bends.