The Tu'att are a reptilian species with an amazing similarity to the Terran tuatara. They appear in the Hevun's Child trilogy.
They have a vestigial third eye in the backs of their heads, and use them to detect movement from behind them.
They're matrilinial, and matriarchal. Females are viewed as more emotionally stable and reliable than the males. Most of this is prejudice from several self-fulfilling prophecies.
The Tu'att use temperature control to ensure the hatching of a female child. In the event of an unwanted male child, he's highly likely to be abandoned by his mother.
They had conquered six systems, including a Terran colony world called Hevun.