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Spinosaurs show semi-aquatic oxygen isotopes
From: Ben Creisler bh480@scn.org
In case this ref has not been mentioned yet:
Oxygen isotope evidence for semi-aquatic habits among
spinosaurid theropods.
Romain Amiot, Eric Buffetaut, Christophe Lécuyer, Xu Wang,
Larbi Boudad, Zhongli Ding, François Fourel, Steven Hutt,
François Martineau, Manuel Alfredo Medeiros, Jinyou Mo,
Laurent Simon, Varavudh Suteethorn, Steven Sweetman,
Haiyan Tong, Fusong Zhang, and Zhonghe Zhou
Geology 38: 139-142 (February 2010)
Abstract:
Spinosaurs were large theropod dinosaurs showing peculiar
specializations, including somewhat crocodile-like
elongate jaws and conical teeth. Their biology has been
much discussed, and a piscivorous diet has been suggested
on the basis of jaw as well as tooth morphology and
stomach contents. Although fish eating has been considered
plausible, an aquatic or semiaquatic lifestyle has seldom
been suggested because of the apparent lack of
corresponding adaptations in the postcranial skeleton of
spinosaurs, which on the whole is reminiscent of that of
other large terrestrial theropods. On the basis of the
oxygen isotopic composition of their phosphatic remains
compared with those of coexisting terrestrial theropod
dinosaurs and semiaquatic crocodilians and turtles, we
conclude that spinosaurs had semiaquatic lifestyles, i.e.,
they spent a large part of their daily time in water, like
extant crocodilians or hippopotamuses. This result sheds
light on niche partitioning between large predatory
dinosaurs, since spinosaurs coexisted with other large
theropods such as carcharodontosaurids or tyrannosaurids.
The likely ichthyophagy and aquatic habits of spinosaurids
may have allowed them to coexist with other large
theropods by reducing competition for food and territory.