RE: Another query: Baryonyx a facultative quadruped?

[Tim Williams <twilliams_alpha@hotmail.com>]

Jenya Lipatov wrote:

> Charig and Milner, circa 1996 I believe, proposed that _Baryonyx
> walkeri_ may have been a facultative quadruped, but there was no
> definitive evidence for this. Have there been any developments since
> then on the issue of quadrupedalism in any Spinosaurids?

The issue of quadrupedalism in _Baryonyx_ has, by and large, died a natural 
death.  There is no compelling evidence that spinosaurids were anything 
other than terrestrial bipeds.  Ditto for other large terrestrial theropods 
that have been regarded by some researchers as possible quadrupeds (e.g., 
_Xuanhanosaurus_).

Some theropods may have been quadrupeds when they first crawled out of their 
eggs, when their big heads pushed their centers of mass well forward of the 
hips.  Some small theropods (especially maniraptorans) were probably 
arboreal quadrupeds - i.e., using their arms and legs to climb trees.  But 
there is no good evidence that any theropod is or was habitually quadrupedal 
on land.



Tim