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Re: Swiming spinosaurus



A little late on some replies, but I don't like to leave questions
unanswered

Demetrios M. Vital wrote-

> Doesn't Dicraeosaurus have lengthened neural spines, as well?

Yes, spines on the cervical, dorsal, sacral and proximal caudal vertebrae.
The third cervical through seventh dorsals' are bifurcated.  Amargasaurus is
similar, but its cervical neural spines are very slender and pointed, much
like Dimetrodon's dorsal neural spines.  This is why Amargasaurus is thought
to have double cervical sails.

> Are there any theropods known that aren't obligatory bipeds?

No non-avian theropods, though it's hypothesized that Baryonyx could stand
quadrupedally.  Xuanhanosaurus was once thought to be possibly quadrupedal,
but has too short of forelimbs (Rauhut, 2000).  Then there's Xenicibis, the
supposedly facultatively quadrupedal ibis.

> You mean, if the vertebrae are from an allosaur, as recently speculated?

Exactly.

> Isn't it definite that Baryonyx lived in a different environment?

Well, yes.  The holotype of Baryonyx was found in a fluvial or mudplain
environment, with areas of shallow water, lagoons and marsh (Charig and
Milner, 1997).  The holotype of Spinosaurus was found in the Baharija
Formation, which was consisted of vegetated tidal flats and tidal channels.
However, we would also have to consider the referred remains of both genera
and the possibility they inhabited a greater diversity of habitats than they
are preserved in.

> Are the centra of Stromer's spinosaur vertebrae more like those of
> allosaurs or Suchomimus, if that question can even be answered by his
> drawings?

Interesting question.  If only I had my copies of Stromer's (1915) figures,
I could answer this well.

Mickey Mortimer