That is, of course, they are anything reptilian-like. They could have a reptile-like tail and still be covered in fur. Look at rats, they have fur on almost all parts of their body except their feet and tail, which are scaly. For all we know, Yugiri could be a race of rat-like beings. It wouldn't be out of the realm of possibility, especially since she is a ninja (and there is a very famous rat ninja in the TMNT universe).