My second example of concept art is the work Julia Pott (another personal favourite, in fact she is my favourite illustrator/animator of all time) created before her latest short animation 'Belly'.
Although these are again only rough sketches to get an idea down on paper, it really shows how she has developed her idea (especially when looking at the faint rubbing our marks and her own unique numbering system to help organise herself). There are no T-pose examples which she has created, however you can see that she has experimented with different poses for each character (which can clearly been seen in the first image, and again in the second).
Belly from Julia Pott on Vimeo.
Again you can see the similarities and differences between the concept work and her finished piece.
http://motionographer.com/2012/07/24/julia-pott-belly/ In this article Julia talks about her work in general (not so much the character development side however), and it contains more images taken from her Flickr, of concept sketches, backgrounds and her at work.
Her website is packed with work from the cute to the creepy and is well worth a look: http://www.juliapott.com/