[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
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
> defend that reconstruction. A "2-pointer" level fin [can't quite find the
> 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
> 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...