Based on the thread-OP, my general feeling is that any species which is independent of Terran-origin should truly be as "alien" as possible. This is not to say that there might not be some analogs or similarities in certain ways, but it should always be remembered that life that is independent of Earth should not necessarily follow the "tropes" of Earth-life.
If you are designing a species that you envision as having certain characteristics that remind humans of reptiles (or dinosaurs), the most important thing you can do in your mind is divest yourself of the thought that it is "like a dinosaur" or "like a reptile". Reptiles (et al) are a taxonomic classification of Terran life. There are NO reptiles on other worlds that are not Earth-derivative. They may look "reptiloid" (in fact, I often further distance myself from that comparison in my mind by using a term such as "pseudo-reptiloid" or "pseudo-mammaloid" , etc)), but they are NOT reptiles (or mammals). Which means that morphological structures and biological processes that you would normally consider part of reptilian biology would most likely NOT be paralleled in a "reptiloid" alien. (I.e. Just because an alien has a few features reminiscent of reptiles does not necessarily imply that they are cold-blooded, egg-laying, etc - or even that they have a "spinal cord" along a "backbone" that comprises a central nervous system).
