Re: Swiming spinosaurus

["Mickey Mortimer" <Mickey_Mortimer11@msn.com>]

Steven Coombs wrote-

> So is there anything else done on other animals much older than the
> dinosaurs as Dimetrodon and Edaphosaurus, and do these animals have neural
> arches similar to Spinosaurus (And others) and biffaloes? Because they are
> to been seen as having a sail on there back as well. Animals like
> Rebbrachiosaurus, Ouranosaurus and also Barsboldia, these animals are
> bacically quadruped while Spinosaurus and Acrocanthosaurus are bipedal.
Why
> for exmaple we get other Spinosaurids such as Baryonyx which does not have
a
> sail on its back. In Suchomimus it has tall neural arches about half the
> lenght as Spinosaurus, it seem that it evolved in time.

Bailey examined basal synapsids like Demetrodon and Edaphosaurus and found
they have very different neural spines than most tall-spined dinosaurs and
mammals.  Their spines are very gracile, cylindrical, much higher and taper
to points.  They are similar to those of modern lizards with dorsal sails.
The only dinosaur found to have spines like this was Amargasaurus, in the
cervical area.  So Amargasaurus may have had a double sail on its neck.
Remember that the limbs of Spinosaurus are completely unknown.  There is the
possibility it wasn't obligatorily bipedal.  Acrocanthosaurus has very short
spines compared to Spinosaurus (4 times as tall as centra, versus 11 in
Spinosaurus).  There would be very little problem with a hump in that genus,
even though it is obviously obligatorily bipedal.  Baryonyx and Suchomimus
may not be related to Spinosaurus, if the latter is a chimaera (Rauhut,
2000), though I will have to see better evidence for this before I believe
it.  Even if Baryonyx is a spinosaurid, why wouldn't there be variation in
the family?  Perhaps Baryonyx lived in a different environment, hunted
different prey, or had a different form of locomotion.  Suchomimus does not
have very tall neural spines, certainly not half the height of Spinosaurus'.
They reached a maximum of 3.1 centrum height, less than a third of
Spinosaurus' height.

Mickey Mortimer