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RE: Size of *Neoceratodus africanus* and/or *N. tuberculatus*







I was reading all your posts on the
Spinosaurus diet and again, as Augusto said, there is much speculation on what
you said.

But as long as we don't have any direct evidence of the diet of Spinosaurus,
they will only be assumptions logically.



The first point is that all we know of the feeding habit of Spinosauridae are
three direct evidences:



1) Disarticulated skeletal remains of a young Iguanodon showing some evidence
of abrasion in the stomach region of Baryonyx. (Charig and Milner, 1997).

2) Acid-etched scales and teeth in the common Mesozoic fish Lepidotes in the
stomach region of Baryonyx. (Charig and Milner, 1997).

3) A spinosaurid tooth embedded in the cervical vertebrae of an ornithocheirid
pterosaur which is rather an evidence of predation because "the vertebrae
lack evidence of etching by gastric juices" (Buffetaut et al., 2004).



In conclusion, the Spinosauridae were carnivorous and piscivorous animals which
could eat pterosaurs and (juvenile?) dinosaurs.



But non-direct evidence about the anatomy of Spinosauridae (the weakness of the
skull, the narrowness of the snout, the conical teeth, the finely serrated
teeth, the subnasal depression, the long neck, the position of the external
nares far from the tip of the snout, the fig claws,...) demonstrate that they
were not super-predators (such as the Tyrannosauridae and the
Carcharodontosauridae) and they Were very well adapted to catch fish and eat
them (rather than being scavenger).



About Spinosaurus, we know that it had the facility to swallow big prey thanks
to the helicoidal shape of its mandibular condyles and the short mandibular
symphysis that joint the jaws
(http://www.svpca.org/general/pages/abstractPage.php?i=1441&r=talksAndPosters.php&y=2008).
We can observed the wideness of the pharynx in piscivorous animals as
Pteranodon and the living pelecanids. Furthermore, it lived in the same
ecosystem as Carcharodontosaurus, Sigilamassasaurus (which belong to an unknown
Tetanurae family), Deltadromeus, abelisaurid, dromaeosaurid and according to
Nizar Ibrahim that I heard on the last SVPCA, oviraptorosaurid dinosaurs. 
(http://www.svpca.org/general/pages/abstractPage.php?i=1398&r=talksAndPosters.php&y=2008).
Therefore, I strongly believe that Spinosaurus was confined in the niche of a
piscivorous animal rather than a predator or a scavenger one. And its huge size
does not contradict this hypothesis because, as David Marjanovic said,
Spinosaurus lived in a fluvial ecosystem where big fish such as coelacathiforms
and lungfishes were extremely abundant.



Concerning the living habit of Spinosaurus, it's still hard to have a firm
idea. In my opinion, it could be possible that Spinosaurus was aquatic rather
than terrestrial because we do not have any ideas of the shape of the limb
bones in Spinosaurus. What we know is that the evolution of Spinosauridae
coincide with a neural spine elongation. Stromer (1915) believed it was the
structure of a sail of skin but Bailey (1997) though it was the neural spines
supported a hump of fat or of muscles. That tell us nothing about the diet of
Spinosaurus.



When I gave a talk on Spinosauridae, someone told me that the very elongated
neural spines could support a hump of fat which could help Spinosaurus floating
into the water. Again, it is a new (but quite interesting) speculation 
therefore, in conclusion, we should wait new
discoveries about the anatomy of Spinosaurus (and Spinosauridae) that could 
help us to interpret
the living habit of this dinosaur before proposing many hypotheses that no one 
can demonstrate.





Christophe Hendrickx



Ps: For the reference, check on that page
http://spinosauridae.fr.gd/Bibliographie-du-site-web.htm.Sorry for my Eglish 
mistakes.





----------------------------------------
> Date: Sun, 29 Mar 2009 14:13:11 -0300
> From: augustoharo@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Size of *Neoceratodus africanus* and/or *N. tuberculatus*
>
> I think the long-billed bird analogy does not necessarily mean tying
> spinosaurs to get into water bodies. Marabu storks and some herons
> have long bills yet forage from dry land, and something similar
> happens with the hornbills. They can pick up things with their long
> snout either on land or water. Using other analogy, snout elongation
> in carnivorous mammals is not related to aquatic habitats.
>
> May it be that large spinosaurids mostly eat land prey, mostly animals
> well-smaller than themselves, waiting for them near river courses?
> This would be more logical in arid regions such as the Sahara, where
> many tetrapods will have to go to the river with some regularity
> because of the water scarcity. This would put spinosaurids in contact
> with fishes, overall those that walk into the water, like some
> catfishes. Or to rob their prey to smaller fishers that have lesser
> trouble getting into the mud, including smaller spinosaurid specimens.
> Spinosaurids may even dig in dry courses to reach the cocoons of
> lungfishes, they have large claws after all, and their long snouts may
> have helped, as with some sand charadriiforms. I do not know of
> posterior refutation to the 1998 Journal of Paleontology paper stating
> that Spinosaurus had a hump in the back. Because of this, and because
> of the need to accumulate food and water in such an arid environment,
> where water sources may have endured little, I would guess Spinosaurus
> had a hump.
>
> I know, too much speculation.

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