With some idea down I decided to move on to concept images for a proper look into the creature. The main aim was to look into combining the traits posessed by the animals I was using as a base reference. Looking at rats and roosters to see what shapes could fit where.
It was brought to my attention that the creature looked a little stiff. And it was suggested to look into understanding the skeleton as something to build on, as is the purpose of a skeleton. It has helped give some idea and I suppose the next step would be to 'flesh up' for a pose sheet. From my attempts to create a coherent structure, I think I have narrowed odwn on a design. One thing that was of particular interest was that I found that the spine of a rat tends to arch upwards between the base of the shoulder blade and the hip when it is on all four legs, likely what gives the distinctive rear arch many rodents possess.
One thing I considered investigating was the skull. I looked at images of rat and chicken skulls, drawing them in order to understand what forms or intricacies the two may have shared that could be useful in a combinaiton of the two structures. Some leements are indeed shared, but at the same time there are notable structural differences. The chicken skull has a number of large gaps and thin bridges, likely an evolutionary feature to help reduce the creature's weight, while the rat skull by comparison was a lot more block-like, with a more solid snout and a larger encased area for the brain (which might explain why rat eyes somewhat bulge out of the head).
With all this in mind I moved on to try and merge features of the two, although I wonder if the head I created from the attempt looks like a hawk's. In hindsight I also recall that like in humans and other animals, the nose of a rat is spongy cartilage, not bone, and thus continues forward from the nasal openings. This differs from the beak of a bird, where the nostrils are holes in the skull and any cartilage present is used to reduce the size of these holes.