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Re: Spinosaurus redescribed as giant semiaquatic theropod

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(including some skepticism by other paleontologists about conclusions...)



On Thu, Sep 11, 2014 at 11:14 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> It's out...
> Nizar Ibrahim, Paul C. Sereno, Cristiano Dal Sasso, Simone Maganuco,
> Matteo Fabbri, David M. Martill, Samir Zouhri, Nathan Myhrvold, and
> Dawid A. Iurino (2014)
> Semiaquatic adaptations in a giant predatory dinosaur.
> Science (advance online publication)
> DOI: 10.1126/science.1258750
> http://www.sciencemag.org/content/early/2014/09/10/science.1258750.abstract
> NOTE: Supplementary material is free.
> We describe adaptations for a semiaquatic lifestyle in the dinosaur
> Spinosaurus aegyptiacus. These adaptations include retraction of the
> fleshy nostrils to a position near the mid-region of the skull and an
> elongate neck and trunk that shift the center of body mass anterior to
> the knee joint. Unlike terrestrial theropods, the pelvic girdle is
> downsized, the hind limbs are short, and all of the limb bones are
> solid without an open medullary cavity, for buoyancy control in water.
> The short, robust femur with hypertrophied flexor attachment and the
> low, flat-bottomed pedal claws are consistent with aquatic
> foot-propelled locomotion. Surface striations and bone microstructure
> suggest that the dorsal “sail” may have been enveloped in skin that
> functioned primarily for display on land and in water.
> ==
> Michael Balter (2014)
> Giant dinosaur was a terror of Cretaceous waterways.
> Science  345(6202): 1232
> DOI: 10.1126/science.345.6202.1232
> http://www.sciencemag.org/content/345/6202/1232.summary
> Researchers have long debated whether dinosaurs could swim, but there
> has been little direct evidence for aquadinos. Some tantalizing hints
> have appeared, however, in claimed "swim tracks" made by the bellies
> of dinos in Utah and oxygen isotopes indicating possible aquatic
> habitats in a group of dinosaurs called spinosaurs. Now, a research
> team working in Morocco has found the most complete skeleton yet of a
> giant carnivore called Spinosaurus, very fragmentary remains of which
> were first discovered in 1912 in Egypt. The new fossils not only
> confirm that Spinosaurus was bigger than Tyrannosaurus rex, but also
> show that it had evolutionary adaptations—ranging from pedal-like feet
> to a nostril far back on the head to high bone density like that of
> hippos—clearly suited for swimming in lakes and rivers.