Saurian was a taxonomical term used to describe some sentient reptilian species, particularly those with an evolutionary history similar to Earth dinosaurs. The term may also apply to lizards and reptiles.
One reptilian species whose members served in Starfleet by the 23rd century was known simply as "Saurians". (TOS: "Requiem for Methuselah"; Star Trek: The Motion Picture; DIS: "Brother")
The Voth referred to themselves as a saurian race. The Voth had very poor relations with non-saurian races, and many Voth treated members of such species, particularly mammalians, as lower lifeforms. (VOY: "Distant Origin")