Spinosaurs seem to had been efficient terrestrial predators, or at
least scavengers, according to the the pterosaur and iguan[o!]dont
fossils.
Why "efficient"? That's not something we can tell from a sample size of 2.
And some like Spinosaurs were a bit too big to feed just on fish.
There were insanely large coelacanths and lungfish in those days.
*Mawsonia*
got to over 3 m, and *Neoceratodus africanus*... there's a JVP paper I'll
have to check on Monday... the illustration at the end of
http://www.cprm.gov.br/publique/media/Cap14_15.pdf may well be to scale.
Also interesting:
http://scienceblogs.com/laelaps/2008/04/was_spinosaurus_really_the_big.php
http://whenpigsfly-returns.blogspot.com/2008/01/feeding-adaptations-and-strategies-of.html
And *Purussaurus* coexisted with *Lepidosiren megalos*, which was 2 m long
instead of the 0.5 of *L. paradoxa*. The toothplates of that beast were 4
cm
long. http://www.sbpbrasil.org/revista/edicoes/8_1/toledo&bertini.pdf