Kraoka

(Dig those titles and authors.)

"A Sun Invisible."

Are the Kraoka credible aliens? My guess would be that, if a fictional alien can be quickly and easily described just by comparing its bodily features to those of two or three Terrestrial species, then it is not a plausible outcome of an entirely independent evolution.

A Kraok is like a two meter tall tyrannosaur with brown fur, a shimmering, ribbed dorsal fin, anthropoid arms, four-fingered hands, round head, tufted ears, blunt muzzle, (presumably two) small eyes, body parts indicating one of the three sexes, brassard, pouch belt and sidearm.

Each finger has (what we regard as) an extra joint. I get the impression that Anderson tries hard to make the details different.

So, despite all these differences, human beings and Kraoka can use similar furniture and equipment. They can learn each other's languages although a vocalizer helps them to sound right.

We also need to read about alien psychology:

males are small, meek, child-rearers;
females are creative decision-makers;
transmitters are more belligerent.