RE: Spinosaurus redescribed as giant semiaquatic theropod

[<john-schneiderman@cox.net>]

With its very visible dorsal sail, Spinosaurus would not make a good ambush 
predator. Instead it most likely scavenged terrestrial creatures or made good 
use of a watering spot/crossing when terrestrial prey were overcrowded or in 
crisis.

John Schneiderman

---- dale mcinnes <wdm1949@hotmail.com> wrote: 
> 
> Perhaps Spinosaurus ambushed terrestrial prey in the manner of crocs 
> positioning themselves
> 
> close to the path of a migratory herd during a crossing ??
> 
> 
> > Date: Tue, 30 Sep 2014 15:00:31 +1000
> > From: tijawi@gmail.com
> > To: dinosaur@usc.edu
> > Subject: Re: Spinosaurus redescribed as giant semiaquatic theropod
> > 
> > Dale McInnes wrote:
> > 
> >> I'm going to suggest something here. The way that spino's "fin" is now
> >> reconstructed is actually quite interesting. I'll leave it up to the 
> >> authors to
> >> defend that reconstruction. A "2-pointer" level fin [can't quite find the 
> >> right
> >> word for it] might be a lot more natural than a smoothly constructed
> >> semicircular fin, especially for camouflage. I would suppose that there 
> >> would
> >> be a lot of debris in the form of branched logs floating around in thos
> >> backwaters where spino converged upon. A color pattern of a low horizontal
> >> thick brown/gray stripe accompanied with "branching" vertical stripes just
> >> might conceal this enormous predator in the form of a large floating 
> >> branched
> >> log in amongst others. It just might get close enough to shore to grab an 
> >> unwary
> >> verte taking a drink. More stealth than a crocodile .. maybe.
> > 
> > 
> > 
> > The authors interpret _Spinosaurus_ as a semiaquatic predator that
> > targeted aquatic prey: sharks, sawfish, coelacanths, lungfish,
> > ray-finned fishes. (BTW, there were some whopping big lungfish around
> > at the time.) The concept of _Spinosaurus_ as an ambush predator
> > awaiting the approach of thirsty terrestrial prey is difficult to
> > accord with its overall size (specifically height). It would be
> > difficult for an adult _Spinosaurus_ to 'lurk' in shallow water.
> > 
> > The piscivorous , semiaquatic lifestyle inferred for _Spinosaurus_ has
> > been compared to early cetaceans ("archaeocetes"). One major
> > difference is that early cetaceans evolved from terrestrial
> > quadrupeds, whereas theropods were bipeds (and still are). The
> > semiaquatic _Spinosaurus_ has been regarded as a quadruped when on
> > land, due to its highly reduced pelvis and hindlimb. We'll have to
> > see how this mooted terrestrial quadrupedality stacks up with future
> > discoveries regarding the pectoral/forelimb/manus morphology of
> > _Spinosaurus_. It is even possible that _Spinosaurus_ rarely ventured
> > onto terra firma, except to lay eggs (like hesperornithids).
> > 
> > As a sidebar, the humerus referred to _Spinosaurus_ is especially 
> > contentious...
> > 
> > https://twitter.com/JohnRHutchinson/status/510961698782457856
> > 
> > 
> > 
> > 
> > 
> > 
> > Cheers
> > 
> > Tim