Ear tufts are present at hatching (although not always noticeable). With the bird feathering out as slowly as you say, I am not yet willing to say it is rumpless. Looking at your photo, it actually looks a great deal like my granddaughter's serama. That would fit with the slow growth, too. Our Teeny is the only serama we've ever had, so I cannot give a truly educated opinion that that is what your Tiny IS, just that she looks like our Teeny did at that age.
