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Re: Lack of Running Giant Theropod Tracks



David Marjanovic <david.marjanovic@gmx.at> wrote:

> Yes. Press articles at the time this discovery was announced said "this
> stuff supports hotels" about the compact sand ground in question.


The press releases I recall likened _Paralititan_'s habitat to the Everglades.


> Utterly unsurprising -- theropods had large feet with long, somewhat splayed
> toes; even at the same weight, this means less risk of sinking in than for a
> pillar-footed sauropod.


Yes, I don't doubt that certain sauropods became mired in soft mud.
After all, this is what happened to at least one specimen of
_Giraffatitan brancai_ (SII).  The humerus and tibia were preserved in
an erect position, suggesting that this individual became stuck, and
died where it stood.  There is no evidence of scavenging.


> Oxygen isotope ratios tell us where *Spinosaurus* got its food from, not if
> it ever swum. I think it was a heron analogue.


I had thought that the oxygen isotope ratios tell us directly about
the animal's aquatic habits, not just what it ate. Spending time in
water minimizes enrichment of 18-oxygen in body water, due to factors
such as reduced aerial evaporation when the body is immersed.  So the
oxygen isotope ratios of _Spinosaurus_ indicate that it was
semi-aquatic.  That was my impression, anyway.


Also, I would assume that if spinosaurids were
piscivorous/ichthyophagous that they spent much of their time *in* the
water, catching fish - such as humongous lungfish.



Cheers

Tim