Wow look at all the views on this thread. Mind you its an old thread xD
Anyway nice sprites. Its nice to see an improvement, good job.
On the platypus line, the ridge on the beak is rather off-centered on both sprites but mainly the second one. Also, on the second one, its arms are kinda weedy for its size, which I think makes the anatomy look off. Lastly, it looks a little fat, unless that's what you intended. However good job on them and the others too, very nice use of dithering.